This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Tuesday, January 19, 2016

Gullies and debris flows on Mars: Liquid water or dry ice phenomena???

Dark spots attributed to dry ice along gullies in Lyell crater.
In the January 2016 issue of Nature Geoscience, there is one paper and one News and Views commentary that take on the currently popular idea that gullies and debris flows on Mars are caused by liquid water. These two papers advocate a major role for dry ice, CO2. (Unfortunately, neither article references an important paper by Troy Shinbrot and colleagues in 2004 in which the title says a lot: "Dry granular flows can generate surface features resembling those seen in Martian gullies," PNAS, 101(23), 5 pages. This model appears relevant to the mechanism in part (b) of the cartoon below.)
      The commentary by Colin Dundas (Nature Geoscience 9, pp. 10-11, 2016) sets the stage by summarizing the context. Although the gullies look like terrestrial landforms caused by running water, there is a real problem finding the source of the putative water. Groundwater discharge is frequently cited, but this is inconsistent with the occurrence of gullies on sand dunes and isolated peaks. "Whatever the water source, wet models imply the repeated occurrence of thousands of cubic meters of liquid water at each gully, which would have profound implications for both climate and possible biology on Mars." Over the past two decades photographs of the surface have documented channel erosion and the deposition of debris flows in locations where the present climate is too cold for substantial liquid water. However, many (most?) of these locations occur where seasonal CO2 frost occurs, and gully activity occurs mainly in the winter and spring when CO2 frost is observed on the slopes and is available for participating in gully formation.
      In the major article, Pilorget and Forget (Nature Geoscience, 9, 65-69, 2016) develop the model with numerical simulations. Referring to the second figure here, the model is as follows: (a) At the end of winter, the H2O-ice cemented soil (dark blue) is overlain by a regolith and a mantle of CO2 ice (light blue) that is ~1 m thick at the poles and thinner toward mid-latitudes. As the solar intensity increases solar rays penetrate through the CO2 ice and are absorbed by the regolith. This leads to a pressure and temperature increase in the regolith, and the formation of CO2 ice in the pores (light blue circles) of the regolith. (b) When the pressure in the regolith reaches and slightly exceeds the cryostatic pressure of the CO2 ice layer, it rises and cracks, releasing the pressurized CO2. Any remaining CO2 ice in the pores quickly sublimates, and the now-mostly-dry regolith destabilizes and flows out forming viscous granular debris flows because the cryostatic pressure is sufficient to mobilize the grains. (c) Flow of the material thins the regolith, destabilizing the H2O ice underneath and it loses the H2O through sublimation. (d) The process results in the local ice table moving deeper into the crust and the formation of incisions that become, or enhance the formation of, gullies.
     The model used is one-dimensional and examines the evolution of a column that consists of a regolith underlying a CO2 ice layer and an atmosphere. The atmosphere is in radiative-convective equilibrium and the incident radiation on slopes of varying angles is computed. In the CO2 ice layer and the regolith, heat conduction and radiative transfer through the ice are calculated, as well as diffusion, condensation and sublimation of CO2 and the latent heat exchanges (all described in the Methods section). CO2 is predicted to condense above 50 degrees latitude on flat surfaces and down to ~30 degrees latitude on pole-facing slopes.  In such locations, subsurface H2O-ice in equilibrium with the atmospheric water vapor is expected to be present below a layer of dry regolith ranging up to several centimeters thickness. This justified treating the model regolith as a dry porous layer lying above an impermeable, ice-cemented soil.

Monday, December 21, 2015

Horrific landslide slams industrial park in Shenzhen, China

Building after hit by landslide, from CNN.com here        

On Sunday, noon local time, a landslide (mudflow?) slammed into an industrial park burying, according to recent CNN reports, 22 buildings according to the CNN report, 33 buildings according to a NYTimes.com report. The site appears to be fairly close to Hong Kong on the north side, and in an area of steep hills. Accounts are obviously very preliminary at this time. Three buildings housed workers. 1500 rescue workers are on site combing through rubble. A section of a major pipeline carrying natural gas exploded when hit by the slide. A video of one building collapsing is available here (from CNN.com), but it doesn't show anything of the slide/flow itself.  I will update this if more information becomes available, and I recommend keeping an eye out for a post on AGU's Landslide Blog. Dave Petley hasn't posted anything as of the time I'm writing (approximately midnight, US west coast time), but he will likely have a thorough report in the near future.

The Twitter account of the official People's Daily, citing the Ministry of Land and Resources, reports that the material that flowed was a huge pile of construction debris.

Tuesday, November 3, 2015

Great meteor fireball over Bangkok

From BBC.
I don't know if the link below will work, but if it does, it's a great video of a meteor in the sky over Bangkok. I've never seen a fireball trail that "bursts" several times as this one does. In the image at the left, the thin tail in the upper right is the remnant of at the first burst at high altitude, the center one is stye second, and the left one is just appearing. The meteor appears to have burned up shortly after the third burst appears. Easier to see on the video than to describe!


If the link doesn't work, Google "Fireball meteor lights up Bangkok skies" on BBC.com.

I guess that I should speculate on what is causing this (though I suspect that there's a literature out there somewhere that I can't find.)  As the meteor enters the atmosphere, friction causes it to heat up and glow brighter and brighter.  If the part of the crust that is heated spalls off, it would perhaps cause the rapid brightening burst as well as expose a cold interior. That cold interior is then exposed to the atmosphere, friction heats it up, and it spalls off again to form the second burst.  The cold nucleus then heats up to form the third, and final, burst.

Rule of thumb is that "shooting stars" are about the size of a pea. So, maybe this meteor that caused the triple burst was the size of a....golf ball?? Input welcome!

Friday, October 23, 2015

Hurricane Patricia --Category 5 aiming for Mexico

Hurricane Patricia on Friday morning 10/23/2015, from Weather.com

As I write this, Hurricane Patricia is less than 100 miles off shore of Mexico, aiming for landfall south of Puerto Vallarta and north of Manzanillo.  Evacuations have been underway. Mexico's second largest city Guadalajara lies inland fortunately south of the projected path that will take it into southern Texas. It is expected to make landfall Friday afternoon or evening, and to fizzle out near Monterrey on Sunday.
     Patricia is a Category 5 with sustained winds of 200 miles per hour in a small area about 15 miles across near the center. For comparison, the definition of a Category 5 hurricane is one with sustained winds of 157 miles per hour, so Patricia is a strong Category 5. Individual gusts can reach strengths of 50% greater than sustained winds**, implying gusts of 300 mph or 133 meters per second.  Since the speed of sound in air is ~340 meters per second, these winds have a Mach number of nearly 0.4! Mike Smith of Accuweather has drawn the analogy that Patricia is like a 15-20 mile wide EF-4 to EF-5 tornado. Since a mile-diameter tornado is huge, this gives a feel for the size of the dangerous region of this hurricane.
     Patricia has taken the record for the lowest pressure in any hurricane ever recorded with a pressure in the eye of 880 millibars. Hurricane Wilma set the record at 882 millibars ten years ago. Patricia is the strongest hurricane ever recorded in the eastern Pacific. Rainfall amounts of 8-12" are projected with isolated instances of 20". Wave heights near shore have increased already and a dangerous storm surge is expected at the landfall site. Fortunately the inland terrain is mountainous and shear between the storm and the mountains will cause the hurricane to weaken within about 36 ours.
     Category 5 storms tend to cluster into El Nino years because warmer sea surface temperatures and reduced wind shear favor their formation, though there are exceptions.  Since this is the year of the so-called "Godzilla' El Nino, it'll be interesting to follow this season.

     For comparison, here's a link to a post that I did on Super Typhoon Haiyan two years ago, and here's a link to a list of Category 5 Pacific hurricanes.
**Landsea, Christopher W. "Tropical Cyclone FAQ Subject: D4) What does "maximum sustained wind" mean? How does it relate to gusts in tropical cyclones?"Atlantic Oceanographic and Meteorological Laboratory. National Oceanic and Atmospheric Administration. Retrieved 2006-03-16.

Various weather sites, however, are projecting maximum winds of the order of 250 miles per hour.

Wednesday, October 14, 2015

Jupiter's Red Spot is shrinking!!

Comparison of Jupiter's Red Spot
with Earth. Image from
After a 2-month hiatus, I'm going to work my way back into regular posting. But will start in a very lazy way by referring you to a really cool video here, a new NASA time-lapse portrait of Jupiter!
      Jupiter is the largest planet in the Solar System with an equatorial radius of about 11 times that of the Earth, and about 1/10 of the radius of the sun.  It is a gassy planet, and it's upper atmosphere consists of about 75% hydrogen and 24% helium by mass, with a trace of methane, water, ammonia, .... It's atmosphere spans 5,000 km (3100 miles) in altitude, though since Jupiter has no solid surface of rocks like the earth, the base is rather arbitrarily defined as the point where atmospheric pressure is about 10 times the surface pressure on Earth.
     The Great Red Spot is a vortex, an anticyclonic (rotating counterclockwise) storm that is known to have existed since 1831, and possibly since 1665 where it was reported in the very first volume of the Philosophical Transactions (of England)  that a small spot in the biggest of the three observed belts had been spotted with a twelve foot telescope. The Great Red Spot is about three times the diameter of the earth as shown in the image to the left. It "sticks out" above the surrounding cloud tops by 8 kilometers.
      For a technical paper on the topic, see Asay-Davis et al., Icarus, 203(1), pp. 164-188, September 2009, in which they show that "between 1996 and 2006, the area circumscribed by the high-speed collar of the Great Red Spot (GRS) shrunk by 15%...."

Saturday, August 15, 2015

Glacial outburst floods at Mount Rainier

From National Park Service
A glacial outburst flood is a large sudden release of water from a glacier. These are common in Iceland where they are known as Jokulhlaups (o with an umlaut that I can't do in a blog). Here is a link to an impressive video of one in 2010 during the active phase of Eyjafjallajokull.

From The Olympian
On Thursday afternoon, August 14, about a half acre of the South Tahoma Glacier on Mount Rainier broke off, triggering a series of outburst floods. The Rainier outbursts were very very small by Icelandic standards, but at least one was fortunately captured on video. A park volunteer heard a "loud roaring sound, followed by the sounds of water moving boulders and the cracks of breaking trees." Fortunately, that volunteer and another nearby were able to get to high ground, from which they observed the outburst stages. Debris flows were reported at 9:40 a.m., 10:30 a.m., 11:30 a.m., and 12:40 p.m. The 11:30 event generated a debris flow that reached the Westside Road at noon. The road was sufficiently damaged that it will be closed for the weekend. In total, seven waves of debris were recorded.  The debris ended up in Tahoma Creek valley. The Nisqually River saw a 0.5 foot rise during the afternoon. Since 1980 more than 30 debris flows have been recorded from the South Tahoma Glacier. Hot dry weather and/or heavy rainfall trigger the events.

Friday, July 24, 2015

#PacificWarmBlobMustDie--a fun article by Scott Sistek on our warm and dry Northwest

Photo from Scott Sistek article
July 23, 2015 Komonews.com

I don't usually just reference a news article, but this one today by Scott Sistek in KOMONEWS.COM is a great read, and explains the # in the title of this post:


Thursday, July 23, 2015

Kepler spots potentially habitable planet like our Earth

Temperature of the Earth under present
conditions with a solar flux of 341 W/m2,
and just before the runaway greenhouse is triggered
for a mean solar flux of 375 W/m2.
From the Leconte et al. article referenced in text.
NASA has just released an announcement this morning that the Kepler spacecraft has spotted a planet about 60% bigger than our Earth in a habitable zone of a star "similar to our sun."  The planet is dubbed Kepler-452b, and it's about 1400 light years from Earth in the constellation Cygnus. It's gravity would be about twice that of the Earth's. The star around which it orbits is a G2-type star like our sun, has the same temperature, is 20% brighter, and has a diameter about 10% larger.
Cover of Science in 2014
     Aside: Todays announcement is  a bit confusing because a year ago the Kepler team had the cover photo and a report in Science (v. 344, no. 6181, pp. 277-280, 2014) titled "An Earth-Sized Planet in the Habitable Zone of a Cool Star." This star has a radius of about 1/2 that of our sun, but the planet, Kepler 186f, is in the habitable zone and could support liquid water if it has an earth-like atmosphere and water at the surface. It appears that the difference between these two announcements is that the star around which Kepler-452b orbits is more similar to our sun than the Kepler 186f star.

      In 2013, Sid Perkins wrote a piece in Nature (December 11, 2013) discussing the habitable zone and summarizing the work of Jeremy Leconte at the Pierre Simon Laplace Institute in Paris (Leconte et al., Nature, 504, 268, 2013).  Leconte ran the first fully three dimensional model of hot, very moist planetary atmospheres (and thus the work only applies to planets that have abundant water like the Earth; there is no evidence yet whether the newly discovered planet in Cygnus has water). Previous models had been one-dimensional and considered only how the atmospheric conditions changed in the vertical direction, ignoring horizontal transport effects, whereas this model can take account of the Hadley circulation. Leconte et al. conclude that the runaway greenhouse will take effect at a mean solar insolation of about 375 W/m2. In this model, warming of the planet causes the formation of cirrus clouds at high altitudes. Such clouds trap heat, and the heating leads to more evaporation, which leads to more clouds and thus the feedback to a greenhouse effect. The model also suggests that the large-scale circulation (not possible in 1-D models) creates cloud-free areas in the mid-latitudes that allow heat to radiate back to space. The conclusion is that the inner edge of the Solar System's habitable zone is about 142 million kilometers from the sun.  Earth is at 149,600,000 kilometers so we are close to the inner edge of the habitable zone. Other authors, however, have concluded that the inner boundary could be considerably closer especially for planets that have much less water to feed the greenhouse effect (Petigura, et. al., Proc. Natl. Acad. Sci. USA 110, 19723, 2013).
     Wiki has a good summary of habitable zone thermodynamics here.

Monday, July 20, 2015

Recommended Readings!

From this web site
I don't usually post reviews or recommended readings, but at the behest of a couple of valued readers, here are two that are highly recommended:

On the scale of future disasters in the Pacific Northwest, Kathyryn Schulz "The Really Big One," is eloquent, accurate, and incredibly readable:


And, a moving tribute to Claudia Alexandra, a prominent African American planetary scientist/engineer, who tragically died at age 56:


Tuesday, July 14, 2015

Pluto, at last!!

The last photo of Pluto for a bit, hopefully more soon.
New Horizons' should reestablish contact with earth
Tuesday night (7/14/2015) and begin sending 10 years
worth of data back to earth, a process that will take 16 months.
NASA image.
Congratulations to Alan Stern and the teams on New Horizon, the spacecraft that has spent a decade getting out to Pluto! To emphasize what a feat this is, here's a quote from a NASA press release:

"New Horizons' almost 10-year, three-billion-mile journey to closest approach at Pluto took about one minute less than predicted when the craft was launched in January 2006. The spacecraft threaded the needle through a 36 by 57 mile (60 by 90 kilometers) window in space--the equivalent of a commercial airliner arriving no more off target than the width of a tennis ball."

Pluto was discovered only 85 years ago by Clyde Tombaugh, an astronomer at the Lowell Observatory in Flagstaff. Tombaugh was doing a systematic search for a planet, dubbed "Planet X" at the time, beyond the orbit of Neptune. He would take photographs of the sky several nights apart and compare the images using a "blink comparator," an image that allowed rapid comparison of images. With this technique, astronomers can distinguish between stars, which do not move, and moving objects such as asteroids, comets and, in Tombaugh's case, a planet. It showed up very close to the place that Lowell had predicted.
Kuiper Belt (blue dots). Attribution:
WilyD at English Wikipedia
The yellow dot is the sun.
J,S,U,N are Jupiter, Saturn, Uranus, and Neptune.

Pluto resides in a region of the Solar System known as the Kuiper belt, shown in the image here.  It was believed, until the 1990's, that Pluto was uniquely large and the Kuiper belt objects were unknown. Hence, Pluto was called a planet. The Kuiper belt was discovered in the 1990's, causing some to call Pluto's status as a planet into question, and with the discovery of Eris in 2005, a body 27% more massive than pluto, Pluto's status was sealed. The International Astronomical Union had to define the term "planet" for the first time because there was the possibility of "too many" planets!! To the dismay of some (many?) Pluto was demoted to a "dwarf planet" category.

So, what are the basics known or believed to be known at this point? The size of Pluto had been uncertain, and one result already from New Horizons is a new diameter--2370 km, up from an earlier value of 2302 km. This diameter is only about 2/3 of the diameter of the Moon. It's acceleration of gravity is 0.067 g, escape velocity is 1.23 km/s. The surface temperature varies between 33-55 K, with a mean of 44 K, truly a frigid planet. It's atmosphere consists of nitrogen, methane, and carbon monoxide at a maximum summer pressure of 0.30 Pa. The surface is 98% nitrogen ice. The color varies from black to dark orange to white--being similar to that of Io (the satellite of Jupiter that looks like a pizza).

Is there the possibility that tectonic or "volcanic/geyser" activity will be discovered on Pluto? The interior is believed to have a dense rocky core of approximately 1700 km diameter, and if radioactive heating is still significant today, it's been speculated that there could be a subsurface ocean 100-180 km thick at the core-mantle boundary.  Here's a New Horizon's blurb that summarizes some of the facts and possibilities. We've been surprised before (Io, Triton, Enceladus) so here's hoping for some action!!

Go New Horizons Team, and thank you!!

Monday, July 13, 2015

New prediction of a "mini ice age" during the 2030's

A sun without any sunspots, photo taken on July 17, 2014
Photo from here.
I am reluctant to feature research here that hasn't been through peer-review, but it's a losing battle as prestigious groups, such as the British Royal Astronomical Society, release press releases about exciting ideas. So, take the following for what it is worth, it's at least interesting to think about!

Here is the reference for the press release.

The sun's activity varies over a solar cycle of roughly 11 years (22 years if the polarity of sunspots is considered). To date, the cycle has been analyzed the phenomenon in terms of a dynamo driven by fluids convecting deep within the sun. A dynamo is a fluid dynamic condition of convection within a body that moves a convecting, rotating, and electrically charged fluid around within a body. Traditionally, solar physicists attempt to explain the measured properties of the sun and their variability with a single dynamo within the sun. We had a prolonged drought of sunspots over the past two years, but there are a few now and they emit strong enough particles to cause some concerns about telecommunications.
Sun configuration on July 13, 2015
From space weather.com

Valentina Zharkova is presenting a paper at the National Astronomy Meeting in Llandudno that proposes two dynamos: the traditional one deep in the sun, and another close to the surface. Each dynamo gives a periodicity of about 11 years, but they are slightly different and offset in time. The idea is that if they coincide appropriately, the effects will be large. The data are based on observations from 1976-2008. Running the model into the future, the model predicts that during Cycle 25, which peaks in 2022,  and into cycle 26 (2030-2040) the waves due to the two dynamos will become exactly out of synch. This would result in a reduction in solar activity equivalent to the Maunder minimum of the 1600's, 370 years ago.

It will be interesting to follow this because the implications are enormous for global stability and economics. I recommend the great website space weather.com to follow solar events.

For a bit of prehistory, and my interest in the sun, my first published paper was a documentation of the evolution of sunspot groups, in the inaugural edition of a new journal Solar Physics: Zirin, Harold and Werner, Susan, Detailed analysis of flares, magnetic fields and activity in the sunspot group of Sept. 13-26, 1963, Solar Physics, 1, pp. 66-100, 1967,

Thursday, June 25, 2015

New Old Faithful Geyser Video available

Jim Westphal (1930-2004)
The results of a video-probe that descended into Old Faithful in 1991 are available on YouTube here (copyrighted video). My colleague in this project was the incredible experimentalist, Jim Westphal of Caltech, we were aided by long-time collaborator and Yellowstone Park geologist, Rick Hutchinson, and the efforts of the U.S. Geological Survey and the National Park Service this year made it possible to get the best possible quality video on-line. The challenges in building this probe were numerous because so little was known about the geometry of the conduit at the time. Literature reports included estimates that the conduit was over 100' long, but the most reliable estimates were smaller than that. We knew that the conduit would be dark and filled with hot steam and we knew that the probe would have to pass through a constriction only 4" in dimension, but otherwise we were descending into the unknown.  In the early 1990's, the cumbersome video equipment of previous decades had finally become small enough that we could design an ice-cooled, self-illuminating, system to lower through the constriction into the conduit.  You can see the camera and the video system as well as the conduit down to about 40' in the video. Enjoy!

Wednesday, June 10, 2015

Wind River earthquake of 2013: unusually deep and in the mantle

Scenary of the Wind River area illustrating that the
surface is covered with sedimentary rocks and
supporting the observation that there is no
active volcanism within about 200 km. From the BBC
article by Matt Walker cited in the text.
Today the BBC has a nice article  by Matt Walker pointing out an article by T.J. Craig and R. Heyburn in Earth and Planetary Science Letters (425, pp. 12-23, 2015) on a very deep earthquake in the Wind River range of Wyoming. The authors point out that while earthquakes in the mantle of the oceanic lithosphere are common, well-documented and well-constrained earthquakes in continental mantle are rare, partly because not only must the depth of the earthquake be constrained, but the depth of the Moho also has to be known. In 2013 there was a M4.8 earthquake in the Wind River Range of central Wyoming, a region that is normally relatively quiet seismically.  Only once in the past ~60 years has a M5 earthquake been recorded, and most quakes do not even exceed M4. This earthquake, and one single aftershock, were initially recorded to be between 70-80 km depth.
     The (very mathematical) analysis in this paper constrains the depth of the earthquake to 75 km (plus or minus 8 km), and makes it the second deepest earthquake now identified under a stable continental region. The depth of the Moho in this area is well constrained to be between 42-50 km, so the earthquake occurred well within the mantle, probably >20 km below the base of the crust.  The only two other comparable earthquakes that the authors know of are the 1979 Randolphe, Utah, quake at 90 km, and the 2000 Arafura Sea earthquake at 61 km.
     What caused this earthquake? The authors mention the possibility that the quake may result from the migration of fluids within the mantle.  Such activity is known to cause microseismic activity at great depths in volcanic regions. However, the Wind River range is more than 200 km from the nearest volcanic region, the hot spot of Yellowstone. They also argue that since the Wind River earthquake ruptured an area of about 1,000,000 square meters, this area is much larger than would be expected from fluid-related origin.  They cannot rule out this possibility, but prefer an explanation that the earthquake resulted from brittle fracture due to tectonically-derived stresses.

Sunday, May 24, 2015

Texas/Oklahoma flooding, record rains, Lake Texoma flooding

The jet stream patterns that have set up the current
wet situation in Texas. From Weather.com here
on May 24.
Over 350 homes in Hays County, Texas, are gone, and more than 1000 are damaged according to reports coming out this Memorial Day weekend. At least one person in Texas and two in Oklahoma have died as a result of the storms. The Blanco River surged up 28' in 2 hours as the flood surged to 40', three times the flood level.  And as of this (Sunday) evening, more rains are expected, perhaps 3-5" more.
Lake Texoma is the 12th largest US Army Corps of Engineers lake, behind the Denison Dam on the Red River.  It spans both Bryan County, Oklahoma, and Grayson County, Texas at the confluence of the Red and Washita Rivers. The dam site is 5 miles northwest of Denison, Texas. It is a popular lake, attracting about 6 million visitors per year. Water is pouring over the
Lake Texoma Spillway the morning of Sunday,
May 24. From TKKToday here. This is an excellent
site to see current and forecasted conditions as well
as helicopter footage of the flooding.
spillway of the dam for only the fourth time in its history as the inflow to the Lake is 300,000 cubic feet per second (for reference, this is about ten times the maximum discharge of Glen Canyon Dam, and three times the discharge during the 1983 crisis at Glen Canyon Dam). The Denison Dam here was built during World War II, finished in 1944, in order to control flooding along the Red River. spillway previously in 1957, 1990, and 2007. Water pouring over the spillway goes back into the Red River and is not considered a danger to those living in Denison.

U.S. Severe weather map as of 12:26 a.m. GMT (7:26 p.m.
CDT) on May 25 from www.wunderground.com here
As explained on Weather.com with the graphic at the top of this post, in April, the conditions that were causing the drought this past winter in California shifted. The subtropical jet has a trough per the southwest, allowing cyclonic storms to breed over the rockies. These, in turn, enhanced the flow of warm moist air up from the Gulf of Mexico for the past six weeks.

As the severe weather map shows, much of the central U.S. is experiencing severe weather in the form of flood warnings and watches, tornado warnings (red), and high wind advisories (blue and pale green near Chicago).

Saturday, April 25, 2015

Magnitude 7.8-7.9 earthquake strikes near Katmandu, Nepal

Location of earthquake and initial aftershocks
From CNN.com
Added on 4/29: Here is a link to an Andrew Revkin article in the New York Times with excellent information about why Max Wyss thinks that the death toll could reach 57,700, and the range of uncertainty. 

Map added on 4/26 at bottom showing avalanche problems on Mount Everest.

A strong earthquake occurred in Nepal about 14 hours ago, and as I write this the death toll from the earthquake  has risen to 1,457, with more deaths expected.  The people face a cold night without shelter, water or electricity in many regions. The world's thoughts are focused on the people of Nepal with hopes that rescue efforts proceed smoothly an rapidly.

           Max Wyss, Switzerland, runs a research program WAPMERR, in which he combines geographic data with seismic models to predict the injured and dead, with results sent to authorities and emergency people to aid in the planning of rescue and recovery (Note: you can subscribe to his service on the home page of WAPMERR). Unfortunately, his estimates are for 2000-10,000 fatalities, and 20,000-70,000 injuries. (Wyss's estimates have been updated to the numbers that I cite here just in the time it has taken to write this post, so check back with his site if you want updated information.)

According to the USGS, large earthquakes in this region have been relatively rare with only four events of M6 or larger known to have occurred within 250 km of this earthquake site. Two of these were a M6.9 earthquake in 1988, that caused about 1500 casualties and a M8.0 event in 1934 at roughly the same location of this 1988 event that severely damaged Katmandu and caused around 10,600 casualties.

Image from Dave's Landslide Blog showing the
location of the earthquake according to USGS model
Image from Blog as cited in the text
The earthquake struck near noon local time (11:56 a.m.), 11:11 p.m. the previous day, west coast time in the U.S. A magnitude 6.6 aftershock occurred about a half hour later, and strong aftershocks continue. It was centered less than 50 miles west of Katmandu, with aftershocks surrounding the capital on the north and east (see map). Katmandu sits in a valley of 1,000,000 people. There are reports that roads buckled in Tibet, and that avalanches were triggered on Mount Everest. The magnitude of the earthquake has been reported from M7.5-M7.9, and the epicenter at 7-12 km. These estimates should get better as seismologists have time to refine the models and analyze the data, but it is clear that the quake was quite shallow.

The Indian and Eurasian plates are converging at a rate of 45 mm/year, one of the fastest rates on the planet. This motion drives the uplift of the Himalayas. India is thrust under Eurasia, and the motion between the two plates makes this one of the seismically most hazardous regions in the world. The surface expression of the fault (along the red line in the figure below) in the vicinity of Nepal is marked by the east-west trending Himalaya Front in the north of India and Nepal sits within this belt. To the north is the high Plateau of Tibet. An excellent detailed summary of the regional tectonic setting is available on the USGS events page reporting the current earthquake found here.

The tectonic boundary between the Indian plate (bottom)
and Eurasian plate (top) with the red line showing
the surface location of the collision of these
two plates. USGS map as published today in USAToday.com
A 2004 thesis by Bierendra Kumar Piya concluded that there was a significant potential for liquefaction in the Katmandu valley in the case of a strong earthquake. He noted that liquefaction occurred in parts of the valley in the 1934 earthquake, which this one closely resembles, so we expect to see reports of damage to buildings and infrastructure due to liquefaction. There is also a strong possibility of landslides. Dave's Landslide Blog at AGU (starting on April 25, 2015) will be updating and discussing the landslides.

The situation on Mount Everest as
shown in NYTimes.com

News is trickling in that devastating avalanches have killed approximately 20 people on Mount Everest. Sadly, the best time to climb Mount Everest from a weather perspective is now, April and May. Sadly, on April 18, 2014, thirteen people were killed in an avalanche, at a site well known for its danger.  There is a dangerous ice fall, known as the Khumbu Icefall, where seracs (unstable blocks of ice separated by cracks in an ice field) loom large over the route.  Climbers usually try to pass quickly through here in the early morning before rising day temperatures amplify the hazard.  According to Wiki, citing Russell Brice who runs a guide company called Himalayan Experience, ice falling from the serac narrowly missed climbers in 2012, and according to another mountaineer/writer, Jon Krakauer, the 2014 avalanche was triggered when a large block of ice broke off from the bulge. The Khumbu Icefall and the location of the 2014 avalanche are shown on the adjacent figure. It will be very interesting to see if the present large avalanche originated at the same site, but travelled much further all the way down the ice fall to cause so much damage in the Base Camp.

Remember that Nepal is landlocked. Tom Robinson of the University of Canterbury has done a preliminary analysis of the roads likely to be affected by landslides; that analysis is available on Dave's Landslide Blog here. The rescue situation w is dreadfully complicated with the airport closed and most access roads damaged by landslides. (Correction: The airport is open and India and China are flying in relief.) The monsoons are less than two months away, and since it is likely that many rivers are blocked by landslides, air and satellite photography of the landslide settings is essential to analyze future flooding due to blocked rivers.

Saturday, April 4, 2015

Tornado outbreaks forecast for week of April 6; lunar eclipse

Dr. Greg Forbes of the Weather Channel
reviewing large tornado outbreaks
Just because I moved out of the Midwest doesn't mean that I have lost my interest in tornadoes! So, to my friends in Illinois, I'm still thinking of you!! Forty one years ago there was a "super outbreak" of 147 tornadoes through Illinois, Indiana, Kentucky, Tennessee, Alabama, Georgia, and surrounding states. All told, there were 147 tornadoes recorded on April 3-4, 1974. This was exceeded only on April 26-28, 2011 when 293 tornadoes were recorded. Joplin, Missouri, was destroyed (more information on this is available in Chapter 8 of my book, The Dynamics of Disaster, shown in the left sidebar).

Now, meteorologists are warning of a severe weather outbreak, including tornados, for the midwest next week. What do meteorologists look for to predict a tornado outburst days or even a week into the future? First, they look for the jet stream to plunge to the south, bringing strong winds westerly or southwesterly winds and cold air aloft.  Second, they look for warm and humid air flowing up from the Gulf of Mexico at lower levels, pushed by southerly winds. Being less dense than the cold dry air, the warm humid air is unstable.  The required four ingredients are: warm air, cold air, moisture and winds. Low-level winds blowing with different strength at different elevations set up shearing that produces a horizontal spinning vortex, and regions where winds rise, producing updrafts, draw air flowing along the surface and its vortices in and up.  A third layer of air, hot and dry, develops between the lower warm moist air and the colder upper air. This layer acts as a cap that prevents the warm moist air from rising, allowing it to warm even further, creating a positive feedback that makes the instability even greater. As the system moves from west to east across the U.S., the lift increases, the capping dry air is removed and explosive thunderstorms can develop.
From here.

The winds circulating around a low pressure center provide a mechanisms that can spin up a normal thunderstorm into a huge rotating vortex known as a "supercell." Supercells contain strong, rotating updrafts. Because they are so big, they are usually isolated from other thunderstorms in the area, sucking up energy and moisture from miles around. Tornados seem to develop within a supercell several thousand feet above the ground. Tornados begin in the supercell as a rotating, funnel-shaped cloud extending from the base of the supercell. When the funnel cloud is half-way between the cloud base and the ground, it formally becomes a "tornado."

BTW, last night was a short total lunar eclipse, and here's a link to a time-lapse of it from USAToday. 

Friday, March 13, 2015

The "Vanuatu Monster" storm

From CNN

From Wiki

First of all, where is and what is Vanuatu? It's an island nation of volcanic origin in the South Pacific some 1000 miles east of northern Australia. If you subscribe to the USGS earthquake notification system, you'll see a lot of alerts about earthquakes near Vanuatu. 65 of Vanuatu's 82 islands are inhabited. The islands are steep, prone to landslides and slippages, and there is little permanent fresh water. The shorelines are rocky and drop quickly into oceanic depths because there is no continental shelf. The active volcanoes are Lopevi and Mount Yasur, with eruptions (undersea) recorded in 2008, and another in 1945. About 267,000 people inhabit the islands. Many people live on less than $1/day, and the infrastructure is weak.
Four cyclones at once

Although two cyclones in the same basin at the same time is not uncommon in the Atlantic or Pacific, four storms at once is rather rare. There are currently four simultaneously in the southern Pacific: Olwyn, Nathan, Bavi and Pam. There have only been four simultaneous hurricanes at once in the Atlantic two times, in 1893 and 1998.* The 1893 hurricane claimed between 1000-2000 lives in Georgia and South Carolina.

Pam, at category 5, is the strongest storm to make landfall since Haiyan hit the Philippines in 2013. Pam has already hit Port Vila, the capital of Vanuatu, a city of 44,000 people. It is likely to hit southern Vanuatu islands early Saturday morning local time. Pam has sustained winds of 165 mph, but as of the time of this writing (Friday, 1:00 PDT which I think is Saturday at 1:00 a.m. in Vanuatu) the reported gusts have been 60 mph. Storm surge and "very rough to phenomenal seas" are expected to affect particularly the central and southern islands.

It's a bit difficult to know what to believe about barometric pressures, as there are no reconnaissance aircraft in the vicinity. Pressures in the eye have been reported to be as low as 870-890 mbar's. If true, the 890 mb is lower than all known hurricanes except Wilma in 2005 (882 mbar's) and Gilbert in 1988 (888 mbar's).  The lowest pressure ever recorded was Super Typhoon Tip (870 mbar's) in 1979.

Why four at once?* There is a wet/dry cycle of 30-60 days known as the Madden-Julian Oscillation, a wave of atmospheric energy that moves east near the equator over these time scales. In one phase, upward motion in the atmosphere is strong, a condition that boosts the formation of thunderstorms. This is the condition now in the western Pacific.This, combined with a strong burst of westerly near-surface winds just south of the equator in the same region this week gave a "boost" to any low-pressure systems trying to get fired up. The result: four storms. See the reference at *, and links within it, for more discussion.

My prayers and thoughts are with the people of Vanuatu as you recover from this storm.

* Discussion from http://www.weather.com/storms/typhoon/news/four-tropical-cyclones-pacific-australia

Wednesday, March 4, 2015

Villarica volcano, Chile, eruption

Villarica eruption March 3, 2015.
AP Photo/Aton Chile
Villarrica volcano is one of Chile's most active volcanoes. It lies along the crest of the Andes in southern Chile, at the west end of three stratovolcanoes that trend perpendicular to the Andes along a fault. The lava is basaltic-andesite and the eruptions are typical Strombolian eruptions that eject pyroclasts several kilometers into the air and lava flows. In 1964 and 1971 massive lahars accompanied the eruptions because of rainfall and melted snow and ice. The current eruption began on February 7th and over 4,000 people were evacuated, but most have returned home as of today as the eruption has waned.

Villarrica has a persistent lava lake in the bottom of a summit crater. It is ~40 m diameter, and in the early 2000's, it ranged from about 20-100 m below the summit crater rim.  In 2004, abundances of gases were measured by Shinohara and Witter, and found to consist of H2O, CO2 and SO2. The gas emissions were the same in the continuous emissions as in lava spattering events, suggesting that the degassing occurs at very shallow levels and that the lava spattering is caused by the bursting of bubbles formed under equilibrium conditions in the magma.
     In 2000, in response to a regional seismic event, the eruption of a small volume of lava apparently plugged the conduit (Ortiz et al., 2003) on September 22. On October 5 and 8, a series of explosions reopened the conduit. Ortiz et al. found that the frequency of the harmonic tremor caused a shift in the peak frequency of the tremor from 1 Hz (open conduit) to 2 Hz (closed conduit). (Aside: This is interesting because it is the opposite of normal pipe behavior for which open pipe frequencies are twice the closed pipe frequencies.)
     In a textural and geophysical study conducted over a 10-day period in 2004, Gurioli et al (2008) found two types of pyroclasts: scoria and "golden pumice." They have identical glass compositions, but different textures, and the authors concluded that they underwent different histories in the conduit.  They interpreted the golden pumice as rising in the expanding inner part of the eruptive jet, and the scoria as forming the outer portion of the jet.  The scoria was entrained during passage of fresh material (that became the golden pumice) through older material in the upper portion of the conduit.


Shinohara and Witter, Geophysical Research Letters, 32(20), L20308, 5 pages, 2005
Ortiz, et al., Journal of Volcanology and Geothermal Research, 128 (1-3), pp. 247-259, 2003.
Gurioli, et al., Journal of Geophysical Research: Solid Earth, 113(B8), B08206, 2008.

Tuesday, February 10, 2015

Milky Rain in Eastern Washington, a donation from Oregon!

Sample of the 'milky rain' that hit Eastern Washington
from KOMONEWS.com here
Sample taken in the rain gauge at the NWS office, Spokane
Last Friday a "white, milky rain" fell across parts of Eastern Washington, Oregon and Idaho, falling on 15 cities and grabbing headlines even in USA Today. Initial speculation about the cause even included the speculation that it was volcanic ash from a distant volcanic eruption. The Walla Walla County emergency management staff attributed the ash to a January eruption of Shiveluch volcano in Kamchatka, 3000 miles away. CNN meteorologist Derek Van Dam pointed out an eruption two days earlier near Colima, Mexico, 2000 miles away.
Summer Lake during an autumn storm
Image from Wiki here, no attribution given

According to the story referenced in the figure caption, by writers Scott Sistek and Nicholas K. Geranios, the explanation is more close by.
 Meteorologists traced the dust backwards to a dust storm over Summer Lake in Oregon on Thursday night. Summer Lake is a large shallow (1 foot-2 feet max depth) alkali lake in Lake County, Oregon. It is surrounded by arid lands, the remnants of an enormous Lake Chewaucan that formed in the late Pleistocene. The last high water was about 13,000 years ago as the Ice Ages ended. As the lake dried up, salts and alkali minerals were concentrated in the remaining waters and in sands and soils around the remaining water. Prevailing westerly winds formed sand dunes that lie on the east side of Summer Lake.
         Last week, high winds lofted these dry alkali sands and soils from the desiccated lake bed according to the NWS Mary Wister. Southerly winds then carried the particles northward, carrying the dust a large distance in less than 12 hours. When the dust got into Washington and Oregon, it ran into rainstorms which dragged it down as dusty milky raindrops.

Friday, January 16, 2015

Typhoon Mekkhala (Amang) and Pope Francis's visit to the Philippines

Typhoon Mekkhala at 2 p.m. Eastern Time Friday
3:00 a.m. Saturday local time in Manila
from CNN.COM
The image at the left was taken approximately six hours before Pope Francis is to fly into Tacloban (see location) to conduct a mass before tens to hundreds of people at 9:30 a.m. local time (8:30 p.m. Friday night ET). CNN is describing this as "likely to be a soggy, windy experience with a measure of peril." Between 13 and 15 cm of rain are forecast (Tacloban and Manila, respectively, more at places nearby). He is scheduled to hold a mass on Sunday morning that as many as 6 million people have been projected to attend, though flooding and landslides may make travel dangerous and difficult. As of this writing, Vatican officials have commented to the press.a
Projected rainfall over the next 48 hours in millimeters.
From the CNN article cited.
     According to AccuWeather.com, Mekkhala's trajectory is most likely to spend the weekend in the central Philippines spreading very heavy rain as it moves slowly to the west northwest. Landfall is likely in Samar, one of the areas hit hard by Super Typhoon Haiyan (Yolanda) only last year. Part of the Pope's schedule is to take him to the eastern Visayas to visit with people impacted by Haiyan.
     Although this is significant and disruptive rainfall, it is an order of magnitude less than the heaviest rainfalls recorded in typhoons. In August 2009, Typhoon Morakot dropped 2900 mm (114") in Taiwan three days. This included the highest, single-day regional record at 1403 mm (55 inches). The damage to infrastructure from flooding and slides was enormous.
    Such heavy rainfalls have not gone unnoticed by people who study earthquakes. Seven months after Typhoon Morakot dropped this rain, a M6.4 earthquake rattled Taiwan. According to Shimon Wdowinski and I. Tsukanov, as reported by Richard Lovett of National Geographic Magazine, heavy rainfall may be triggering these earthquakes. (Note: I could not find a peer-reviewed paper from them, only an AGU 2011 Fall meeting abstract#U53E-06). The M7.0 earthquake in 2010 in Haiti came 18 months after it had been deluged by two hurricanes and two tropical storms. There are difficulties in making correlations between events so far apart in time, and for which there are only a few data points:

  • 2009 Typhoon Morakot, M6.2 in 2009 and M6.4 in 2010
  • 1996 Typhoon Herb, M6.2 in 1998 and M7.6 in 1999
  • 1969 Typhoon Flossie, M6.2 in 1972

But, Wdowinski's analysis suggested that Taiwan's M6+ earthquakes were five times more likely to occur within four years after such storms than if the storms had no effect. Wdowinski suggests that is not the weight of the water that triggers the earthquakes, but the unloading of the crust by landslides and sediment redistribution from the land into the sea. This lightens the stress on the crustal rocks and, if a fault is near failure, makes it easier to slip, that is a typhoon alters the timing of an imminent earthquake. The AGU abstract says that mesh free finite element modeling and Coulomb failure stress analysis were used to calculate the increase in failure stresses at the hypo centers by 300-1500 Pa, ultimately triggering the earthquakes. The say that the statistical analysis indicated "a very low probability (1-5%) for a random earthquake occurrence process to give the observed typhoon-earthquake correlation.
    A slightly different model was proposed by Thomas Adar for the Himalayas. In the monsoon seasons, water flows from the Himalayas into the lowlands where its weight causes a slight bending of the Indian tectonic plate causing the edge of the plate to deform slightly. During the wet season, the bending offsets the tectonic strain on the fault caused by the plate motions and reduces the short-term risk of earthquakes. But, in winter, when the lowlands dry out, the plate unbends and the earthquake rate increases.

Thursday, January 15, 2015

Indian Ocean tsunami--not 2004, but 1945

The Makran subduction zone showing the approximate
source of the earthquake (yellow) that caused
the 945 tsunami (inferred from seismogram and
coastal uplift). Sites with blue circles show locations
of tsunami fatalities. Red dots show locations of
survivors who were interviewed, and fractions
show the fraction of credible first-hand accounts
(denominator is total number interviewed). From the
article referenced in the text.
Eos, Transactions of the American Geophysical Union features an article in the December 23 issue by D.M. Kakar and others about the next-to-last devastating tsunami in the Indian Ocean (on the 10th anniversary of the most devastating 2004 tsunami). Eos, by the way, is now freely available online to everyone at Eos.org, not just members of the AGU.
     Documentation of this earthquake and tsunami was hindered by the international instabilities of World War II and British India. This article is the result of an effort to find the aging survivors of the event and gather eyewitness accounts in order to improve tsunami hazard models and awareness. 
     The earthquake that caused the tsunami was M8.1 and centered west of Karachi (Pakistan) along the Makran subduction zone where the Indian Ocean plate is subducted below the Eurasian plate at a rate of about 4 cm/year. Estimated fatalities are between 300 and 4000, most in the areas of Pakistan, Iran and Oman shown on the map, but thirteen deaths in Bombay (Mumbai). Elders in Oman, Iran, Pakistan and India were interviewed. Most were children in 1945. Although many accounts were "hearsay", others contained details assumed to be real: "For example, the shaking in Ormara brought down a stone house that entrapped one eye-witness's recently married sister. The noisy approach of a wave in Pasni cut short the predawn Fajr prayer. The sea at Konarak entered a mosque and injured some who were praying there...."
     The authors of this article hope that the eyewitness accounts can be used to constrain models of tsunami hazards, and that the eyewitness stories will help educate those who live along the shores about tsunamis.  

Saturday, December 20, 2014

Happy Holidays!

As 2014 winds down and the holidays approach, here again is the Bill and Boyd reminder that Nature doesn't always know about and respect holidays! Have a safe and enjoyable holiday and best wishes for 2015!

Thursday, December 18, 2014

Pancake ice on the River Dee in Scotland

Pancake ice on the River Dee
Photo by Jamie Urquhart, biologist from here
If the Queen of England were in residence at the moment at Balmoral Castle, Scotland, her summer residence, and if she walked downstream a few miles, she'd see the stunning cluster of pancake ice on the River Dee!

How does such ice form? To start with, we probably need to review a phenomenon known as "frazil ice."  Water normally freezes at 273.15 K (32 F), but can be supercooled down to almost 231 K if there are no nuclei for the ice crystals (that is, the water needs to be very pure). Frazil ice forms in turbulent, slightly supercooled water. It consists of small discs of ice 1-4 millimeters in diameter and 1-100 microns in thickness.  It is estimated that sometimes there can be one million ice crystals in a cubic meter of water. As the crystals grow, they will stick to objects in the water and tend to accumulate on the upstream side of objects.  This can cause ice dams and serious flooding.  

Frazil ice in rivers can be a serious problem if there are hydroelectric facilities because it can block turbine intakes, or can freeze open gates. It's also hard on the fish! In the ocean, frazil ice forms around the edges and within open water within ice packs.  Here it has become of concern because of oil and gas development in the Arctic. A review article on this by Sellye Martin can be found in Annual Reviews of Fluid Mechanics, v. 13, pp. 379-397, 1981.)

According to the CNN article referenced in the figure caption, there have been some cold nights in Scotland. They speculate that the disks form at night (and are round because they form in swirling eddies), soften in the daytime so that the rims get pushed up by collisions, and then grow further the next night, etc. Pancake ice is a well understood phenomenon on the oceans.

Wednesday, December 10, 2014

Atmospheric Rivers and the storms of December

Wind gusts forecast for 1:00 p.m. (tomorrow afternoon)
As I logged into Cliff Mass's blog to do my homework for this post, I saw that he had updated his latest post as follows:

"BIG NEWS UPDATE at 10:15 AM Wednesday:  At 10 AM, Seattle-Tacoma Airport reported 65F, the WARMEST TEMPERATURE EVER OBSERVED AT SEA-TAC FOR THE MONTH OF DECEMBER.  I repeat this is the warmest temperature every reported for any day in December in the entire climatological record.  Amazing.  Undoubtedly true of other Northwest sites as well.

"I ([Cliff] had to laugh today when I saw the front page of  the National Weather Service's Seattle forecast office web site. 
They had FOURTEEN watches, warnings, and advisories. 

"I have never seen so many.   Something out of a disaster movie or reminiscent of the plagues that hit Egypt before the Exodus.   High Winds!  Floods! Small Craft Advisory!  High Surf!  Gales! Storms! Rough Bars!  All that was missing were tornadoes, hurricanes, lice, and darkness.  Oh, I forgot, we have darkness living in Seattle during the winter.

"But it is getting very clear that the Oregon coast is going to be ground zero for a major onslaught of wind.  Hurricane-force gusts. "

All of this is being treated by the popular press as the result of an "atmospheric river," (AR) as if that was a new concept, but it's not! Two MIT researchers, Zhu and Newell, 1998*) first described the phenomenon. They found that most of the water vapor in the global conveyor belt is carried in 4-5 long narrow  water-vapor-rich sections that are only about 400 km wide. A much older term describing California storms is the "Pineapple Express" applies to a subset of atmospheric rivers that have a connection into the tropics near Hawaii. When the AR''s draw in moisture from the tropics, they can be extreme. Here's a link to a previous post that I did on atmospheric rivers. It relates to Japanese fire bombs during WWII.
A plot of the amount of moisture in a vertical
atmospheric column for an AR in 2010
(from Cliff Mass, here)

The AR's are rich in water vapor, and because of the pressure gradients that develop in cyclones/hurricanes, they are associated with strong winds. The winds will force the water vapor up and over topography, leading to condensation of the vapor and precipitation in the form of rain or snow. According to the NOAA site referenced below, 42 AR's impacted California during the winters of 1997-2006, resulting in seven floods along the Russian River watershed northwest of San Francisco, a major "New Year's Day Flood" in 1997 that caused over $1 billion in damages, and contributions to other California storms in the Merced and American Rivers. An AR hit the Pacific Northwest in 2006, producing heavy rainfall, flooding, and debris flows with damage excepting $50 million. You can find a list of NOAA's "notable AR's" here.

Here's a quote from an article by Dettinger and Ingram that illustrates what one of these rivers can do:

"The intense rainstorms sweeping in from the Pacific Ocean began to pound central California on Christmas Eve in 1861 and continued virtually unabated for 43 days. The deluges quickly transformed rivers running down from the Sierra Nevada mountains along the state’s eastern border into raging torrents that swept away entire communities and mining settlements. The rivers and rains poured into the state’s vast Central Valley, turning it into an inland sea 300 miles long and 20 miles wide. Thousands of people died, and one quarter of the state’s estimated 800,000 cattle drowned. Downtown Sacramento was submerged under 10 feet of brown water filled with debris from countless mudslides on the region’s steep slopes. California’s legislature, unable to function, moved to San Francisco until Sacramento dried out—six months later. By then, the state was bankrupt.
A comparable episode today would be incredibly more devastating. The Central Valley is home to more than six million people, 1.4 million of them in Sacramento. The land produces about $20 billion in crops annually, including 70 percent of the world’s almonds—and portions of it have dropped 30 feet in elevation because of extensive groundwater pumping, making those areas even more prone to flooding. Scientists who recently modeled a similarly relentless storm that lasted only 23 days concluded that this smaller visitation would cause $400 billion in property damage and agricultural losses. Thousands of people could die unless preparations and evacuations worked very well indeed."
Finally, on another note that picks up on a few previous posts (http://www.geologyinmotion.com/2014/10/update-on-this-years-el-nino.html;  wondering if we are in an El Nino year, Japan's weather bureau just announced that they find that an El Nino has emerged for the first time in five years, and is likely to continue into the winter. This is the first declaration by a major meteorological bureau of the "much-feared El Nino phenomenon." The pattern emerged between June and August and they signs of it in November as well. An El Nino year leads to drought in some parts of the world, flooding in others. 
It should be an interesting few months!

*Zhu, Y, and R. E. Newell, 1998: A proposed algorithm for moisture fluxes from atmospheric rivers. Mon. Wea. Rev.126, 725-735, doi:10.1175/1520-0493(1998)126<0725:apafmf>2.0.CO;2.

http://www.esrl.noaa.gov/psd/atmrivers/questions/ for a summary of into

Sunday, December 7, 2014

A little known, potentially dangerous, volcanic system at Laguna del Maule, Chile

Maule Lake image
from http://earthobservatory.nasa.gov/IOTD/view.php?id=76827
Note the grey lava flow at the bottom center edge of the Lake
Where in the world is the earth moving up at about 1' per year? Not Yellowstone, but at a relatively little known volcanic field that straddles the crest of the Andes at 36 S latitude.  A recent article by Brad Singer et al. entitled "Dynamics of a large, restless, rhyolitic magma system at Laguna del Maule, Southern Andes, Chile" in GSA Today, v. 24(12) pp. 4-10, 2014 describes this field and it's potential danger. The Lake lies within a 15x25 km caldera. The volcanic complex covers about 300 square kilometers, and contains a cluster of stratovolcanoes, lava domes and cinder cones. The volcanoes sit about 90 km over the subducting slab of the Nazca plate.

The field has 13 cubic kilometers of rhyolite erupted during the past 20,000 years. There have been a dozen crystal-poor, glassy rhyolitic lavas during the Holocene (the past 11,700 years).

In March 2013, the Observatorio Volcanologico de los Andes del Sur (OVDAS) issued a yellow alert, indicating a potential eruption within months to years based on an alarming surface uplift over the last 7 years and swarms of shallow earthquakes.  (In 2010 there was a M8.8 earthquake 230 km to the east.) Early activity in the Pleistocene culminated in "a spectacular concentric ring of 36 separate post-glacial silicic eruptions" between about 25,000-2,000 years ago. The most recent eruptions "were from 24 vents and produced 15 rhyodacite and 21 rhyolite coulees and lava domes." The vents encircle the lake basin. Pumice and ash fall deposits in Argentina may equal these flows in volume.  The only comparable Holocene rhyolite flareup, the authors point out, is along the Mono Craters chain in California.

According to Fournier et al. (2010)*, the rate of surface deformation was negligible from January 2003 to February 2004, but then accelerated between 2004-2007. Feigel et al. (2014)^ have found uplift rates exceeding 280 mm/year (28 cm/year; 11 inches per year). In comparison, this is 2-5 times the greatest rates measured for Yellowstone or Santorini.

Electrical resistivity data suggest a magma body with a hydrothermal system at about 5 km depth, at a location that agrees well with the source of inflation inferred from the geodetic data. 69% of recorded earthquakes between 2011 and 2014 are shallower than 5 km, and most occur under rhyolite vents along the periphery of the uplifting region.

Figure 5 in the referenced paper. Hypothesized
cross section of the Laguana del Maule complex.
The current observations are interpreted in terms of the magmatic mush model of Hildreth (2004) and Hildreth and Wilson (2007), a model that was originally developed to explain the integrated observations of the Long Valley system that erupted 650 cubic kilometers of the Bishop Tuff 767,000 years ago. The magma system is inferred to contain a thin boundary layer of granitoid that is solidified against country rocks.  "Inboard" of this is a rigid "sponge" consisting of crystals with some minor interstitial melt, and inside of this is a crystal rich mush. The mush is maintained in its partial molten state by fluxing of heat and magic magma through the deeper parts of the crustal reservoir. Melt-rch lenses develop near the roof, creating a low-density barrier through which the denser mafic magma cannot rise to the surface. This mush near the top can be tapped to provide the recent/future rhyolitic eruptions.

The proposed setting under the volcanic complex is shown in the figure to the right/above. It includes inferences consistent with the rapid uplift, shallow earthquakes, active intrusion of magic magma at 5 km depth, and normal faulting and geodetic data that record radial extension to form the circumference of vents.

*Fournier, T.J., et al., Duration, magnitude and frequency of subaerial volcano deformation events: Nw results from Latin America using InSAR and global synthesis, Geochemistry, Geophysics, Geosystems, 11, doi: 10.1029/2009GC002558

^Feigl, K.I., et al., Geophysical Journal International, v. 196, 885-901, doi:10.1093/gji/ggt438