Tornado Alley--US and Canada

From: http://www.weather.com/blog/weather/8_12879.html

Google "Tornado Alley"-- you typically get maps that are restricted to the US, such as the one at the left.  Do tornados start and stop at our borders? No, Tornado Alley does extend into Canada (right), and some tornados originate in northeastern Mexico; the storm that spawned the large Eagle Pass, TX, tornado in 2007 produced a tornado in Mexico before moving into the US.

*Moisture for these storms originates in the Gulf of Mexico, and it is pulled northward where a trough of low pressure often sets up east of the Rockies in Alberta, Saskatchewan and Manitoba. The area of enhanced tornadoes in Ontario is enhanced by the flow of cool air from Lakes Huron, Erie and Ontario.  Tornados in Canada may be under reported because of the low population density in places.  On average, Canada has about 80 tornadoes per year compared to nearly 1300 in the US, and 2 deaths/year compared to the average of 62/year in the US. One F5 tornado occurred in Canada, the Elie, Manitoba, tornado of June 22, 2007.

*This information from http://www.weather.com/blog/weather/8_12879.html

From the website of the National Climatic Data, Asheville, North Carolina, http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html Image location: http://www.ncdc.noa)

Although tornados are more frequent in the US than elsewhere in the world, they are not unique to the US. 

"Let's Go Rafting!!!!" (that means I'm out of touch until mid-May!)

A Diamond Expeditions boat in Crystal Rapids, 1983
Photo by J. David Rogers, from here.

The Colorado River winds its way for nearly 200 miles below Glen Canyon Dam through Marble Canyon and then the Grand Canyon. Along the way, nearly 100 rapids make rafting the Colorado one of the most exciting whitewater adventures in the world.

Two of the rapids, Crystal and Lava Falls, are rated a 10 on a scale of 10.  Crystal (photo) was formed in 1966 when a debris flow from the tributary, Crystal Creek, temporarily dammed the river.  Discharges into the Grand Canyon have been regulated by Glen Canyon Dam since 1963, ranging between 5,000 and 30,000 cubic feet per second (cfs). These discharges sculpted the debris fan and widened the channel, but Crystal remained a difficult rapid for boating and was the site of many flips of rafts.

In 1983 rapid snow melt from the Rocky Mountains forced engineers at the Dam to release extra water through the spillways and bypass tubes.  Discharges ramped up to 90,000 cfs, and a huge wave developed at Crystal. Why Crystal and not the other rapids? Because the other rapids had, over geologic time scales of thousands of years, seen annual floods in excess of 100,000 cfs and had been sculpted to accommodate these discharges. Not so at Crystal because of the control of Glen Canyon Dam.

The wave that developed was more than 15' high (see photo--the pontoons on the sides of the boat are 3' diameter for scale), and a boat, not as lucky as this one, flipped in the rapids. People were washed up to 15 miles downstream in the frigid waters and one person died.  Another died in 1984 in a similar accident although the wave was not as big as pictured here.

A detailed discussion of this wave is in:

Kieffer, S.W., 1985, The 1983 hydraulic jump in Crystal Rapid: Implications for river-running and geomorphic evolution in the Grand Canyon: Journal of Geology, v. 93, p. 385–406.

Well, fortunately, this is 2011. And, yours truly is off to go rafting!! There's no communication with the outside world once we launch on the river, so, folks, "adios" until mid-May!!

Here's the Bureau of Reclamation update on the Dam operations for April and May:

Glen Canyon Dam / Lake Powell –The unregulated inflow to Lake Powell as of April 18, 2011 has been 545 kaf and the rate of inflow has increased to over 19,000 cfs. Since April 9, 2011 the elevation of Lake Powell has been increasing from what will likely be the low elevation for water year 2011 of 3609.7 feet above sea level. The official forecast for unregulated inflow to Lake Powell for April was 1100 kaf (112% of average). The daily average release rate from Glen Canyon Dam is about 15,500 cfs. The elevation of Lake Powell at midnight on April 18, 2011 was 3610.0 feet above sea level (90.0 feet from full pool).   It is projected that the elevation of Lake Powell could increase by more than 30 feet to a peak elevation of approximately 3643 feet above sea level by late July or early August.

Current Dam Operations

The release volume currently scheduled for April is 940 kaf.  Average daily releases were reduced to approximately 15,500 cfs steady on April 11, 2011 in response to updated capacity estimates for the generating units at Glen Canyon Dam. The reduced elevation of Lake Powell has mad the generating units less efficient which has reduced generation capacity. In order to maintain a sufficient level of available capacity for reserves and regulation (see description in following paragraph), it was necessary to reduce the release rate from Glen Canyon Dam. In early May, releases will likely be steady at about 15,000 cfs for the first 13 days of the month.  On May 14, 2011 it is projected that Units 3 and 4 will be returned to service and when this occurs, releases from Glen Canyon Dam will be increased such that daily peak releases will be about 22,000 cfs and off peak releases will be about 16,000 cfs.  The projected release volume for May is approximately 1.10 maf.        

In addition to daily operations that may or may not include daily fluctuation patterns for load following power generation, the instantaneous releases from Glen Canyon Dam may also fluctuate somewhat to provide approximately 40 megawatts of system regulation.  These instantaneous release adjustments maintain stable conditions within the electrical generation and transmission system and result in momentary release fluctuations within a range of about 1100 cfs above or below the targeted hourly release rate.  The momentary fluctuations for regulation are very short lived and typically balance out over the hour. 

Spinning and non-spinning reserve generation is also maintained at Glen Canyon Dam.  In order for Glen Canyon Dam (and other Colorado River Storage Project dams) to participate in the electrical generation and transmissions system, Glen Canyon Dam must provide a level of reserve generation to assist the local control area to maintain electical supply when unanticipated generation unit outages occur within the control area. Glen Canyon is required to maintain 99 megawatts (approximately 2,650 cfs of release) of capacity in reserve for these unanticipated outages. When an electrical outage occurs, Glen Canyon Dam can be called upon to provide up to an additional 99 megawatts of generation above what was originally scheduled for Glen Canyon Dam for a duration of 2 hours or less. Under normal circumstances, calls for reserve generation occur fairly infrequently and are for much less than the required 99 megawatts.

"Monster Alabama Tornado Spawned by Rare "Perfect Storm" "

Tuscaloosa, Alabama, after being hit by a
huge tornado on April 27, 2011. Photo
from National Geographic Daily News
by Marvin Gentry, Reuters

The headline above is from today's issue of National Geographic Daily News. A tornado, estimated to be a mile wide and an F5 on the Fujita scale devastated Tusaloosa.  The storm system that spawned this tornado has killed 260 people over two days. Meteorologists are trying to determine how long this tornado stayed on the ground, but it could have been hundreds of miles.

I could not explain the science nearly as eloquently as is done in a NASA Earth Observatory discussion of the weather systems that produced the deadly tornados in southeastern U.S. over the past two days, and so here's a link to their site. Here's a video animation of the storm that is absolutely awesome.

The obvious white clouds in the lower middle
part of this picture are the active storms that
ran through Alabama yesterday.
Photo from GEOS satellite.

Unfortunately, for us living in Tornado Alley, April is just the start of the tornado season, as tornados continue through May and into June. Typically the band of tornadic activity migrates north during the season, with Oklahoma, Kansas, and Nebraska seeing tornados in May, and Minnesota and parts of the Dakotas in June.  Illinois is just vulnerable all of the time it seems!  Meteorologists point out that La Nina conditions have existed since the summer of 2010, but seem reluctant to say that this is why this season seems to be off to a particularly violent start.

"Termites eat millions at a bank in India" !!!

Giant Northern Termite
photo from CSIRO, Australia
not copyrighted

It may not be geological fluid dynamics, but at least the headline is fun (and it is related to fluid mechanics, see below!) The Christian Science Monitor reported today that an "army of termites munched through 10 milion rupees ($222,000) in currency notes stored in a steel chest at a bank" in northern India. The "police have registered a case of negligence against bank officials," a procedure for opening an investigation.

So, what is a termite? Not being a biologist, I had to look this one up. Ah, they are closely related to wood-eating cockroaches, an insect that we know all too well in our ancient geology building! The oldest termite fossils date to the early Cretaceous; the Cretaceous extends from 145.5-65.5 million years ago, ending with the giant K/T impact that wiped out the dinosaurs. It is likely that they extend farther back in geologic time by perhaps another 100 million years.

Termites, like ants, some bees, and wasps divid labor among castes (workers, soldiers and reproductive individuals) and are guided by swarm intelligence to  exploit food sources. Swarm intelligence (SI) is a property of decentralized, self-organized systems, and is a concept employed in work on artificial intelligence. In a swarm, simple "agents" interact locally with one another according to very simple rules.  The interactions between such agents leads to the emergence of intelligent behavior at a scale much larger than that of the individual agents. Prominent biological examples are ant colonies, bird flocks, bacterial growth and fish schools. Concepts have also been used in some models of river system formation to optimize the routes of water as it runs from mountains to the oceans. Topography is represented by a grid, and a set of rules is established that directs any water at a point on the grid to a lower place. The process is repeated until the water reaches the ocean, at which point a river network has been established at a scale much larger than any of the interacting grid cells. Voila--fluid mechanics!

Great Lakes Literacy Principles

The Great Lakes, NOAA
From left to right: Superior, Michigan, Huron,
Erie and Ontario.

The Great Lakes, a fragile resource created at the end of the last glaciation, contain 20% of the world's fresh surface water. 20% of the U.S. population, and a significant fraction of the Canadian population, live near these lakes. They support $4 billion fishing industry, $16 billion in boating, 1.5 million U.S. jobs, and $62 billion annual wages (reference here). Yet, in many textbooks, the lakes are not even mentioned (including, in hindsight, the one that I used for two years teaching a sustainability course!!)

In an effort to educate the public, to preserve the resource, and to provide educational materials, several groups have worked together to gather materials for education.  The principles are modeled after the Ocean Literacy movement.

These groups developed "The Great Lakes Literacy Principles":

1. The Great Lakes, bodies of fresh water with many features, are connected to each other and to the world ocean.
2. Natural forces formed the Great Lakes; the lakes continue to shape the features of their watershed.
3. The Great Lakes influence local and regional weather and climate.
4. Water makes Earth habitable; fresh water sustains life on land.
5. The Great Lakes support a broad diversity of life and ecosystems.
6. The Great Lakes and humans in their watersheds are inextricably interconnected.
7. Much remains to be learned about the Great Lakes.
8. The Great Lakes are socially, economically, and environmentally significant to the region, the nation, and the planet.

Material, including a direct comparison with the Ocean Literacy principles and K-12 teacher materials, can be found here.

"Gas Well Spews Polluted Water" --What is "fracking?"

Well drilling in Leroy Township, PA.
Drillers are Chesapeake Energy.
Photo by C.J. Marshall published in
The Daily Review.com

The New York Times today is reporting on a blowout of a natural gas well in rural northern Pennsylvania. The well is in Bradford County, PA. Seven families have been evacuated after the accident, which took place late night last Tuesday. An undetermined amount of fluid containing chemicals from the fracking process has been released into the environment, and officials are monitoring nearby Towanda Creek, which is stocked with trout.

What is fracking? Some will know already because it was the subject of the hit movie "Gasland" last year. It is a controversial process that pits the needs for gas resources against the needs for a clean environment, in this case, particularly, the needs for clean water. "Fracking" is a popular term used for "fracturing" of rocks for the purpose of improving the recovery of oil and gas from subsurface reservoir rocks. It is not a new technique, having been around since the late 1940's when Haliburton introduced it. A version of it was explored extensively in the 1980's and 1990's as a way to circulate fluids in warm areas of the crust to bring geothermal heat to the surface. "Fracking" occurs naturally in the earth when fluids, such as magma, create pressure in the rocks to create dikes and sills, though the term is not used by geologists in this context.

During fracking, fluid is pumped into a well bore at a pressure that cause the rocks hosting the well to fracture.  In order to keep the fractures open after the injection of the fracturing fluid, a substance referred to as the "proppant" is added to the fracture fluid. This is often sand that has been chosen to have a shape and size that will have high permeability.

Fracking is in the news a lot now because of the urgent need for the US to produce its own coal and gas, and a rich reservoir of gas-containing rocks is the Marcellus Formation, a shale that extends through much of the Appalachian Basin in Pennsylvania and New York State. There is an excellent resource here if you are interested in details from the state of New York.

The controversial part of fracking is related to the nature of the fluids injected. Fluids range from water to gels, foams, and sometimes, even gases such as air, nitrogen, or carbon dioxide. Additives are numerous, as evidenced by this list of those allowed in New York State.  (I took this list from the Wiki article on fracking, and it is an extensive article for further materials.)

CAS Number	Chemical Constituent
2634-33-5	1,2 Benzisothiazolin-2-one / 1,2-benzisothiazolin-3-one
95-63-6	1,2,4 trimethylbenzene
123-91-1	1,4-Dioxane
3452-07-1	1-eicosene
629-73-2	1-hexadecene
112-88-9	1-octadecene
1120-36-1	1-tetradecene
10222-01-2	2,2 Dibromo-3-nitrilopropionamide, a biocide
27776-21-2	2,2'-azobis-{2-(imidazlin-2-yl)propane}-dihydrochloride
73003-80-2	2,2-Dobromomalonamide
15214-89-8	2-Acrylamido-2-methylpropane sulphonic acid sodium salt polymer
46830-22-2	2-acryloyloxyethyl(benzyl)dimethylammonium chloride
52-51-7	2-Bromo-2-nitro-1,3-propanediol
111-76-2	2-Butoxy ethanol
1113-55-9	2-Dibromo-3-Nitriloprionamide (2-Monobromo-3-nitriilopropionamide)
104-76-7	2-Ethyl Hexanol
67-63-0	2-Propanol / Isopropyl Alcohol / Isopropanol / Propan-2-ol
26062-79-3	2-Propen-1-aminium, N,N-dimethyl-N-2-propenyl-chloride, homopolymer
9003-03-6	2-propenoic acid, homopolymer, ammonium salt
25987-30-8	2-Propenoic acid, polymer with 2 p-propenamide, sodium salt / Copolymer of acrylamide and sodium acrylate
71050-62-9	2-Propenoic acid, polymer with sodium phosphinate (1:1)
66019-18-9	2-propenoic acid, telomer with sodium hydrogen sulfite
107-19-7	2-Propyn-1-ol / Propargyl alcohol
51229-78-8	3,5,7-Triaza-1-azoniatricyclo[3.3.1.13,7]decane, 1-(3-chloro-2-propenyl)-chloride,
115-19-5	3-methyl-1-butyn-3-ol
127087-87-0	4-Nonylphenol Polyethylene Glycol Ether Branched / Nonylphenol ethoxylated / Oxyalkylated Phenol
64-19-7	Acetic acid
68442-62-6	Acetic acid, hydroxy-, reaction products with triethanolamine
108-24-7	Acetic Anhydride
67-64-1	Acetone
79-06-1	Acrylamide

The concerns with fracking include risk of contamination of ground water with these chemicals, migration of the chemicals and the gas produced to the surface in uncontrolled ways, handling of waste, air quality due to released gases, as well as the usual concerns about natural gas production, such as the practice of flaring. The legal and regulatory challenges are complex, summarized in the Wiki article referred to above.

Storms, tornadoes kill at least 17 across the South; tornados; multivortex tornado

Damage to homes in Tushka, OK, on Friday, April 15, 2011
Tornado here was an F3.
Photo from Tulsa World

The CNN.com headlines today feature the massive and violent storm that has swept across the South. Springtime brings mixed blessings to those of us who live in Tornado Alley which extends from the Gulf of Mexico through the midwest, and amazingly far into Canada where it wraps around north of Toronto to Barrie.  In 1985 13 separate tornadoes crossed southern Ontario, killing 12 people, injuring 224 and causing millions of dollars of damage.  This was part of a larger outbreak that spread across Ohio, Pennsylvania, and New York. Tornados are rated on the Fujita scale, which has a long history, but now, when it is used at all, it has 5 levels.  Level 5 has winds of 300 mph, and the Barrie tornadoes were classified only slightly below this as an F4, "devastating." The original Fujita Scale was replaced in the US by the Enhanced Fujita Scale in 2007. Here's a link to a Wiki article on the Fujita scale.

Track of the deadliest tornado storm in U.S. history
NOAA

On March 18, 1925, the deadliest tornado in U.S. history raced through parts of Missouri, southern Illinois and Indiana.  It was estimated to be an F5, killed 695 people and injured 2027. The path was 219 miles long, with an average path width of 3/4 mile, and it wreaked devastation for 3 1/2 hours. Winds likely exceeded 300 mph. 15,000 homes were destroyed.

While this current storm was out in Oklahoma, where it did severe damage and killed several people, a team of storm chasers captured it on a video featured in the Washington Post, also posted here on YouTube. (Note: This is NOT the photo at the left; I don't have access to photos of the recent tornados, only the video referenced.) Most tornadic systems span one, or occasionally two, funnel clouds that touch down, but this one had two prominent ones, and hints of a third and fourth, starting about 1 minute into the video.  This is a huge storm, with the spawning cloud being wider than the vertical distance between the ground and the base of the cloud.

Multiple vortex tornado near Altus OK on May 11, 1982
Photo from NOAA.

The smaller tornadoes within the system are known as subvortices, or suction vortices. They spin rapidly within the larger overall circulating winds of the major tornado, and can add over 100 mph to the local ground win.  Damage patterns after the passage of one of these systems often consists of a broad zone of weak damage from the main tornado, with narrow strips of strong damage immediately adjacent.  This more severe damage is likely caused by the subvortices. Subvortices are distinguished from "satellite tornados" by their transient nature.

How big is the plume under Yellowstone?

3-D resistivity model from Zhdanov et al. ** A better
figure of this is Fig. 4 in their paper, which compares
the seismic and electrical results, but I am unable to
copy it from the preprint that is posted in GRL. I'll try to
remember to post it when published.

Yellowstone, Wyoming, USA, is one of the world's largest hot spots, with a record of super-eruptions at ~650,000 year intervals (2.1 million, 1.4 million, and 640,000 years ago).  It's fodder for speculation about an overdue super-eruption in press articles and movies. The USGS maintains an active observing program at Yellowstone.

Robert Smith, University of Utah geophysicist, has spent much of his career studying the subsurface conditions and modeling the size of the plume that underlies Yellowstone. In 2009, Smith reported on a seismic study that showed that the plume of hot, possibly partially melted rock, dips downward from Yellowstone at an angle of 60 degrees.  This plume extends 150 miles west-northwest and reaches at least 410 miles depth under the Montana-Idaho border.  This is as far as the seismic imaging permits resolution of the structure.


In a work to be published in Geophysical Research Letters this month**, summarized in this Science Daily article, Smith and colleagues now report on a study of the electrical conductivity beneath Yellowstone, the first of its kind.  Electrical conductivity yields an image of melted rocks plus hot salty water--the geothermal system that surrounds the magmatic plume.  This plume appears larger than that revealed through seismic imaging.  The plume dips at an angle of ~40 degrees to the west, extending ~400 miles east-west, and goes at least 200 miles deep. The overall picture is of a tilted molten core that looks something like a tilted tornado surrounded by a sheath of hot water. Seismic and ground-deformation studies show that the top of the plume flattens out like a pancake about 50 miles beneath Yellowstone--a 300 mile diameter pancake! Blobs of hot partially molten rock break off of the top of this reservoir and rise to feed the shallow magma chamber that is 4-10 miles below the surface in Yellowstone.

**Zhdanov, M.S., Smith, R.B., Gribenko, A., Cuma, M., and Green, M., Three-dimensional inversion of large-scale EarthScope magnetotelluric data based on the Integral Equation Method: Geoelectricla imaging of the Yellowstone conductive mantle plume, Geophys. Res. Lett., doi:10.1029/2011GL047346, in press. 2011.

Reorganized post containing videos of the tsunami

The March 12, 2011, post where I have been filing videos that show interesting phenomena during the tsunami has now been reorganized to reflect the location of the video, to our best ability to determine it. Corrections are welcomed, as are contributions of other videos. We are trying to collect as many as possible that show the rise of the tsunami over time (usually about 10 minutes). Footage that is taken continuously (without the camera being turned off) and that show clearly identifiable landmarks are especially helpful. 

"Largest tsunami" ever recorded: Lituya Bay, Alaska--was it really a tsunami?

Landsat image of Lituya Bay
as presented in the Geology.com article referenced in the text

Often referred to as "the largest tsunami" ever recorded**, a wall of water 1720 feet high surged over a spur of land at the head of Lituya Bay, Alaska, following a rockslide at the head of Lituya Bay, Alaska.  This rockslide was triggered by the magnitude 7.7 Alaska earthquake on the July 9, 1958. An excellent summary and collection of photographs can be found at Geology.com. This report is based on the U.S.G.S. Professional Paper 354-C, "Giant waves in Lituya Bay, Alaska, 1960" by Don J. Miller. Miller had been working in the area documenting evidence for at least four large waves previously, estimated to have been in 1936, 1899, 1874 and 1853-54. The discoverer of Lituya Bay, the French explorer, LaPerouse, noted the lack of trees and vegetation on the sides of the bay in his ship log, commenting that it looked "as though everything had been cut cleanly like with a razor blade."(Reference from here, which also contains an excellent discussion of the event and of possible mechanisms of origin of the wave).

Lituya Bay and the elevations of the wave
from Geology.com based on Miller's USGS PP (1960)

As illustrated in the second figure here, the Fairweather Fault trends nw-se across the head of the Bay, giving it a T-shape.  The weaker fault material has been scoured by glaciers to produce the Fairweather Trench along the fault zone. The earthquake was centered on this fault zone.  A rock slide at the head of the bay (red zone in the second figure) fell from an elevation of about 3000 feet (914 meters); its volume was about 40 million cubic yards (30.6 million cubic meters). (Assuming no resistance from either air or rock that it was sliding along, this highest part of the rockfall would have hit the ground at nearly 300 miles per hour, or 133 meters/second. The center of mass was at about 2000 feet so the average velocity about 240 miles per hour.)

The impact from this rockfall on the water generated a huge splash wave within Gilbert Inlet. The impact of this rock mass disturbed not only the water, but also the sediments under it, and also tore off part of the toe of Lituya Glacier, causing drainage of a subglacial lake.  The "tsunami height" of 1720 m is taken from the height that "this impact splash" reached on the ridge at the southwest side of Gilbert Inlet, in close proximity to the point of impact.  As the splash traveled out into Lituya Bay, it quickly decayed to less than 200 feet high, and maintained a height on the order of 100 feet throughout much of its passage down the Bay.

Remembering that the word "tsunami" means "harbor wave," this wave in Lituya Bay qualifies as a "harbor wave."  It is may be the best studied example of the near-field dynamics of a big splash. Astrogeologists would also call it "impact ejecta."  Further technical references are given at the end of this article.

**An example this wave being called a tsunami is the BBC Nature program Mega Tsunami-Alaskan Super Wave--Amazing Survival."

A hero in Oshima and a possible mystery about the tsunami waves

Abalone fisherman Susumu Sugawara
from the CNN.com article referenced in the text

The stories about the courage and dignity of the people of Japan keep arriving.  Here's just one example:

Susumu Sugawara is a 64 year old abalone fisherman from the island of Oshima, Japan.* (Note: I'm not sure which of the many Oshima's in Japan this island is.  One is 100 miles north of Sendai, and 45 miles from the epicenter of the March 11 earthquake. Another is south of Tokyo, and another is on Sendai.  If someone can help, please comment! I am guessing that it is the one north of Sendai based on the III Marine Expeditionary Force report cited in **, but can't be sure.)  In some areas the tsunami covered the width of the island**.  The residents of Oshima rely on two passenger ferries and two car ferries.  All four ferries and the 325 ton-concrete pier that they were moored to were relocated 400 feet inland, undamaged.

Instead of running to the hills when the tsunami warning came, Sugawara ran to one of his boats, the Sunflower.  He relates that as he passed his other boats he said goodbye to them, apologizing that he could not save them all.  An experienced fisherman, he says that he is used to seeing waves up to 5 meters tall, but that this one was four times that size. It broke repeatedly over his boat.  Sugawara and a very few others may be the only fishermen who have ridden a tsunami and survived.  He is now tirelessly using his boat to make hourly trips to the mainland to provide supplies to survivors on Oshima.

A mystery: There is every reason to believe Sugawara's estimate of a 20 m high wave. He is an experienced fisherman.  Wave heights reported by the media have generally been of the order 10 m, and this would be a mystery in terms of tsunami behavior because the waves steepen and increase in height as they approach land.  However, there are a few reports of a larger wave: In Ofunato, the wave is reported to have reached 77.4 feet in height. TEPCO, the Tokyo Electric Power Co. revised its initial estimate of the wave that hit Fukushima No. 1 power plant from 10 m to 14 meters, saying that they have found traces of the tsunami at that elevation. Hopefully detailed mapping will reveal more details about wave height.  The TEPCO plants were designed to withstand earthquakes of M8 and tsunami waves of 5.7 m at the No. 1 plant and 5.2 m at the No. 2 plant.



Note: In researching this, I discovered that there are a number of "Oshimas" in Japan. One is a small volcanic island called "Oshima-Oshima" not too far from the Oshima island discussed above.  Oshima-Oshima, which lies west of Hokkaido is uninhabited.  It was the source of a very destructive tsunami in 1741 when a portion of its flank collapsed.  Satake, Kenji, "Volcanic origin of the 1741 Oshima-Oshima tsunami in the Japan Sea, Earth Planets Space, 59, 381-390, 2007.

Note: I have continuously updated the list of videos on my earlier post.  In addition, the initial few minutes of this site show some helicopter footage of the tsunami overriding the greenhouses near Sendei.

*as reported http://www.cnn.com/2011/WORLD/asiapcf/04/03/japan.tsunami.captain/index.html?hpt=C2

**as reported in http://www.dvidshub.net/news/68196/japans-road-recovery-iii-mef-cg-visits-island-oshima. The U.S. III Marine Expeditionary Force is helping with relief efforts.

Congratulations, MESSENGER, on reaching Mercury!!

First image of Mercury ever taken from a
spacecraft in orbit around Mercury. Sent from Messenger,
which reached orbit around Mercury on March 17. Photo
sent on March 29, 2011
Photo credit: NASA

MESSENGER has successfully completed a complicated journey through the solar system to reach Mercury.  The path included one flyby of Earth (August 2005), two flybys of Venus (2006, 2007) and three flybys of Mercury (two in 2008, one in 2009).  It's returning the first new spacecraft data from Mercury since Mariner 10 sent data more than 30 years ago. MESSENGER was launched on August 3, 2004.

MESSENGER will be in a highly elliptical orbit around Mercury, coming as close as 200 km to the surface or being as far away as 15,000 km.

The rayed crater in this image is the impact crater Debussy. It is a central-peak crater with rays that extend hundreds of kilometers across the planet. This crater is visible in Earth-based radar images of mercury because of the prominent bright rays. The name honors the famous French composer, Claude Debussy (1862-1918).

Mercury, Venus, Earth and Mars are the rocky planets of our solar system.  Mercury is "extreme": the smallest, and the densest (after correcting for self-compression).  It has the oldest surface, and may have incipient, though not well-developed, plate tectonic features.  It has the most extreme variations in daily surface temperature.

MESSENGER scientists are focusing on six questions: (1) Why is Mercury so dense? (2) What is the geologic history? (3) What is the nature of its magnetic field? (4) What is the structure of its core? (5) What are the unusual materials at the poles (which are permanently shadowed)? (6) What volatiles are important at Mercury?

The MESSENGER website is here.

Mud volcanoes on Mars?

Mounds on Mars in Acidalia Planitia, Mars. From
Oehler and Allen, Evidence for pervasive mud volcanism
in Acidalia Planitia, Mars, Icarus, 208(2),pp. 636-657, 2010.

Since the days of Viking exploration, there has been speculation that mud volcanism occurs on Mars. Candidate features populate the Northern Plains (see review in the paper referenced in the figure caption to the left).  On Earth, mud volcanism is triggered by tectonic compression or generation of hydrocarbons (esp. methane, CH4).  Neither process appears to be prominent on Mars.  Mechanisms that have been proposed include: (1) dewatering of debris flows; impact-related, seismic shaking causing liquefaction; sedimentation with compaction and degassing; and sublimation of CH4 or CO2 clathrates.  The mounds in Acidalia are on a very large scale, and Oehler and Allen favor an explanation that includes the basin's unique geologic setting.  Acidalia Planitia sits where large quantities of sediments were deposited from outflow channels.  It was a "depocenter" for accumulation of mud and fluids from this sedimentation.  The mounds may be attributable to large overpressure developed in response to the rapid outflow deposition, "perhaps aided by regional triggers for fluid expulsion related to events such as tectonic or hydrothermal pulses, destabilization of clathrates, or sublimation of a frozen body of water."  They could account for a significant release of gas, and the process may have created long-lived conduits for upwelling groundwaters.

In a recent article in Earth and Planetary Science Letters (v. 304, pp. 511-519, 2011), Pondrelli et al. reported on possible mud volcanoes within Firsoff impact crater. The mounts are on the crater floor, and appear as isolated or composit cones 100-500 m in diameter, and tens of meters high.  More than 1/3 have subcircular depressions on their apices, 5-39 m deep, interpreted as vents. The mounds themselves are meter-sized boulders embedded in a finer-grained matrix, a mud breccia. The mounds are located on or near faults and are aligned with fractures, suggesting larger pathways for fluid migration along faults related to the impact that produced the crater. The authors speculate that methane was involved in the process of forming the mounds.

Sieverts, millisieverts, and grays--What's up with these radiation units at Fukushima?

Sometimes I wonder why anyone needs to add any more words to the blogosphere because it does appear that everything that's to be written is already written! In this case, Wiki once again has the definitions of radiation units, but I thought that I'd spin it my way to try to make it intuitive.

We are exposed to radiation in a number of different forms, and in a number of different ways. We are bombarded by electrons, positrons, photons (gamma and X-rays), neutrons of varying energies, alpha particles, and fission fragments.   For example, we get dental X-rays, and mammograms, CT scans.  We are exposed to naturally produced radon, and get radiated when we fly in airplanes. Some of us live near nuclear reactor power stations or, in my case, a coal power station (coal is rich in thorium and uranium).  Did you know that sleeping next to a human for 8 hours every night actually gives you a radiation dose? Good grief--how have I lived this long without knowing that? Turns out that our bodies have naturally radioactive potassium! The source of this, and other tidbits (Brazil nuts apparently are the world's most radioactive food due to high radium concentrations!) is PBS.

Radiation is energy, and the amount of radiation (measured in joules) absorbed per kilogram of material is defined in units of "gray." The amount of radiation absorbed per kilogram of human flesh is measured in units of sieverts (Sv).  It is the amount of "grays" multiplied by a weighting factor which takes account of the radiation type, and the body type absorbing it (skin, bladder, bone marrow, etc.) Thus, the sievert is tied to a biological response rather than purely physical dosage. The most commonly encountered multiple of a sievert is the millisievert (mSv), 1/1000 of a sievert.

Dosages can be single, hourly, yearly, or maximum. Typical single dosages are: dental radiography (0.005 mSv), mammogram (3 mSv), or chest CT scan (6-19 mSv).  Typical average hourly doses are: 0.34 microsieverts/hour for Americans and one-half of this value for Australians.  Typical yearly dosages are: 0.0003 mSv/year living next to a coal station; 0.24 mSv/year from cosmic radiation from the sky; 0.28mSv/year from the ground; 0.40 mSv/year from natural radiation in our human bodies; 0.85 mSv/year from the radiation produced by the granite in the U.S. Capitol building. The PBS site mentioned above says that the building is so radioactive due to the uranium in its granite walls, it could never be licensed as a nuclear power reactor site!

Symptoms of acute radiation, within one day, are: 0.25-1 Sv, nausea, loss of appetite, damage to bone marrow, lymph nodes and spleen.  1-3 Sv, mild to severe nausea, loss of appetite, damage to the above organs with recovery probable but not assured.  3-6 Sv, severe nausea, loss of appetite, hemorrhaging, infection, diarrhea, peeling of skin, sterility, death if untreated.  6-10 Sv, above symptoms plus central nervous system impairment, death expected.  Above 10 Sv, incapacitation and death.

Although reports from the Fukushima emergency have been conflicting, the highest hourly rate may have been 8217 mSv/hour.  The normal recommended average limit for workers in nuclear plants is 20 mSv/year, but this has been raised to 250 mSv/year at Fukushima during this crisis. The report today, if true, is that water found in a tunnel at Fukushima Daiichi is emitting more than 1,000 mSv/hour. I don't have specifics on the allowable levels of radiation from coolants inside a nuclear reactor, but referring to the typical average hourly doses that americans receive (0.34 microsieverts/hour), you can see a basis for the statement that this is at least 100,000 times normal levels.

History of the word "tsunami"

Woodblock print of Tsunami by Hokusai

The NPR staff has produced a very nice article summarizing the history of the word "tsunami" both in Japan and in the western world. Japanese officials have kept detailed records of tsunamis, the first dating to December 29, 684, in Nankaido.  It was related to an earthquake with estimated magnitude 8.4. (Records of the tsunamis in Japan are posted by NOAA here.) Our word tsunami originates from two words tsu+nami, meaning "harbor wave." Strictly, the word means a "tidal wave," driven by the alignment of the earth, sun and moon.

Here's a wiki about "tsunami etymology," including the word for it in a few other languages. A tsunami-like wave was described by the Greek historian Thucydides (426 B.C.), and by the Roman historian Ammianus Marcellinus when he described the sequence of events that destroyed Alexandria in 365 A.D., but as far as I can tell they did not appropriate a special word for the phenomenon in either Greek or Latin. The word "tsunami" was brought into English use about 100 years ago when an earthquake on June 15, 1896 caused a tsunami to hit Sanriku, very near the site of the current devastation. There was a report in National Geographic of this event (erroneously) introducing the Japanese term in the context of an earthquake-generated, rather than a tidal, wave.  Tsunami is also both the singular and plural form of the word in Japanese, but in English we generally append the "s" to make it plural.

(I was talking to a stranger in the Chicago airport yesterday and he commented that he hadn't heard the term "tsunami" until the 2004 tsunami devastated Indonesia. I reflected that even newspapers, radio and TV had limited impact until this 2004 event, which occurred coincident with the emergence of the modern internet. It would be interesting to survey the west coast, east coast, and midsection of the U.S. to see what tsunami awareness has been over the past century. My guess is that the west coast inhabitants would have been the most aware because of their exposure to earthquakes and tsunamis in the Pacific Rim, and that the east coast would have some awareness, perhaps correlated with a widely publicized (and controversial) prediction in 2001 that the collapse of the flank of Cumbre Vieja volcano in the Canary Islands would generate a 50 meter high tsunami around the Atlantic basin.)