"Inland tsunami" in Toowoomba, Queensland, Australia; floods in Brazil; Sri Lanka

AP photo from here

More than 375 people are reported dead in floods and landslides in Brazil (note added on 1/17/11: over 600 deaths now reported). A million are reported homeless due to floods in Sri Lanka. Major floods have been occurring in Australia, building up for several months and culminating last night with the flooding of Brisbane, Australia's third-largest city. In spite of individual stories of courage and heroism, there have been at least 34 deaths there. The National Post in Canada reports "Horrific picture emerges of Australia flash floods", and that Brisbane resembled a "war zone" as the flood hit 30,000 properties.

Here and here are two excellent and scary videos of the Toowoomba flood:

The water rose so quickly in Toowoomba that the event has been described as an "inland tsumani".     Perhaps this poem--one verse from a nineteenth century Queensland droving ballad, "The Overlander"  about northern Queenslan--summarizes the setting:

"I come from the northern plains

Where girls and grass are scanty;

Where the creeks run dry or ten feet high,

And it's either drought or plenty."

The whole ballad is sung on this video.

A discussion of the role of La Nina and the North Atlantic Oscillation in these weather events is here. Although there is much speculation on the WWW about the role or implications of these events and climate change, there are also lessons to be learned by looking back 150 years at the history of this part of Queensland.  It is tragically like many, many other places in the world where humans have altered their landscapes. I excerpt the following history from this reference.

For more than a century, the Queensland government had a vision, and determination, to introduce farming into this region. Australian history in the 1800's is complex.  Queensland became an independent state in 1850, with a complex history of replacing pastoralism with farming and dairying--dairying being needed to sustain the farmers until crops were sold, or in case they failed.  In the 1887 a Department of Agriculture was established in Queensland, and by World War One, the region around Toowoomba was exporting grain.

In order to meet the demand for fencing, an enormous number of trees were felled, depleting the forest resource.  Reserves and parks were established in the headwaters, but tree-clearing and increasing stock numbers caused erosion on ridges and compaction of vegetation on floodplains. In the 1870's and 180's, residents of Toowoomba changed the forest into orchards, which caused the water table to rise and swamps to developed.  Drainage became a problem, and mixing of raw sewage and groundwater wells resulted in a series of typhoid epidemics in the 1870's and 1880's. This was corrected by civil engineering and introduction of sewage systems.

However, as has been observed around the world, the replacement of vegetation with urban roads and buildings increased the rate of runoff to the main river channels. Flash flooding became a common experience in the main towns. Thus, more than a century of history preceded the tragedy of this week.

More on flash flood dynamics in a later post.

Thunderstorms, antimatter, and asthma

Image produced by J. Dwyer/FIT, NASA, from this site.

What is antimatter? It is matter composed of antiparticles. Consider our normal particles, electrons and protons, that are the building blocks of normal matter. For example, one electron and one proton combine to become hydrogen. The anti-electron (called a positron) has the same mass as an electron, but the opposite electric charge--in this case, a positive charge. The antiproton would have the mass of a proton, but a negative charge. An antihydrogen atom then consists of an antiproton and an antielectron. Mixing of matter and antimatter results in the annihilation of both, with the production of high energy photons, that is, gamma rays and other particle-antiparticle pairs. Modern concepts of antimatter began in the 1920's when Paul Dirac realised that the Schrodinger wave equation predicted the possibility of antielectrons, which were then discovered by Carl Anderson in 1932. The study of antimatter has largely been the realm of astrophysicists and physicists, but they have been used in medical imaging in positron emission tomograpy (PET).

Scientists using the Fermi Gamma-ray Space Telescope have announced that they have detected beams of antimatter produced by thunderstorms on earth. This was announced by Michael Briggs, a of the Gamma-ray Burst Monitor (GBM) on January 11 at a meeting of the American Astronomical Society. NASA's Fermi spacecraft is designed to monitor gamma rays. The GBM monitors both outer space and the Earth below its orbit. When antimatter strikes Fermi and collides with a particle of normal matter, both particles are annhilated and the GBM detects the high energy gamma rayss produced. In most cases the gamma rays were detected above thunderstorms directly below the GBM, but a few were detected quite far away, as far as 2800 km in one case. Even though the storms were below Fermi's horizon, gamma rays that were produced by it travelled up the earth's magnetic field and struck the spacecraft. Further information is here.

When Googling for information about this phenomenon, I came across a 2008 study by a team of meteorologists and epidemiologists who had found that emergency room visits by asthematics increased in the days after a thunderstorm. They believe that the associated rain and wind break up pollens and spread them around over distances greater than the thunderstorm itself. I remember being surprised when I moved to Illinois that it was such a hotbed of allergies and asthma. What was there to be allergic to here but corn and soybeans? Well, there are other plants than corn and soybeans, and there are lots of thunderstorms!

Other blogs on this site related to storms and weather can be found here: super typhoon Megi,, winter storms in Europe and the Arctic Oscillation, football can be dangerous, and volcanoes and atom bombs.

Winter storm in southeast U.S. Freezing rain expected

Photo by SWK in Urbana, IL

Today a major storm is pounding the southeastern part of the U.S.  A major concern is that the abnormally cold temperatures that will persist through Tuesday will cause formation of ice and freezing rain that will bring down the power lines. Freezing rain is a hazard in the mid-latitude regions of the globe. Although major freezing rainstorms are relatively rare, they are amongst the most costly of hydrometeorological disasters. The Ice Storm of January 5-9, 1998 in Quebec and Ontario caused 25 deaths, left a million householders without power, caused nearly $US 3 billion in damages, and another $US 3 billion in short-term lost economic output and insurance claims. Some climate change scenarios predict that with warming, the amount of freezing rain will increase.  For example,  study of possible changes in south-central Canada during the winter predicts an increase of 85%, 60%, and 40% in northern Ontario, eastern Ontario (including Montreal, Quebec), and southern Ontario, respectively (Cheng, C.S. et al., Natural Hazards Earth System Science, 7, 71-87, 2007).

From Wiki, which adapted this figure
from two figures in Gay, David A and R.E. Davis,
Climate Research 3(1) 209-220, 1993

What is freezing rain? Under certain atmospheric conditions, raindrops become supercooled (cooled below the freezing point without turning to ice) while passing through a sub-freezing layer of air, and then freeze upon impact with cold objects on the surface.  The figure to the right shows conditions under which freezing rain occurs, and contrasts these conditions with those that produce snow, sleet and rain.  Freezing rain is a particular hazard to aircraft because it can add a significant amount of weight to a plane, and can resculpt the contours of the wings.  If an aircraft starts to accumulate freezing rain in flight, the safe and easy maneuver is to descend into warmer parts of the atmosphere. However, the conditions that produce freezing rain near the surface are such that the plane must climb to higher elevations to find warm air, a much more difficult maneuver if the plane has started to ice up.  In 1994, American Eagle Flight 4184 was in a holding pattern 65 miles southeast of Chicago's O'Hare airport.  Ice formed on the upper surface of its wings, causing the autopilot to disconnect and the pilots to lose control.  The plane crashed into a field, killing all 68 passengers and crew.  As a result of this accident, the airplane type (an ATR) was removed from service in most northern hubs prone to icing conditions, and  pilot operating procedures in icing conditions were substantially revised, including non-use of the autopilot under icing conditions.

China's stealth jet: How does it tie in to geology? !!

The purported Chinese stealth jet, J-20. Source of photo unknown.
Reported here.

News has been circulating on the WWW that China has tested a prototype stealth jet.  "Stealth" refers to a complex set of technologies used to make these jets relatively invisible to detection, not many of which are relevant to geologic processes! However, it is being said that the Chinese aircraft resembles the US F-22 supersonic jet, and supersonic flows are relevant to geology.

U.S. Navy photo of an Air Force F-22 Rapter,
June 22, 2009 in the Gulf of Alaska.

The F-22 is a supersonic aircraft (good Wiki summary here). Its roots date back to 1981 when the USAF developed a requirement for a new and superior fighter to replace the F-15 series. The production model was unveiled in April, 1997 and it first flew in September of that year.  There is a contract to Lockheed Martin for 183 jets by the end of 2011. Export of this plane is banned.Supersonic aircraft travel at Mach 1 or higher speeds.  The Mach number is the ratio of the speed of the aircraft to the speed of sound in the medium through which it is flying, in this case, air.  At room temperature, the speed of sound in air is about 343 m/s (about 760 miles per hour)--at high altitudes where it is colder, the sound speed would be slightly lower because it depends on the square root of the temperature.

From http://www.f-16.net/f-16_forum_viewtopic-t-8338.html

When an aircraft is flying at speeds much less than the speed of sound, it creates disturbances that spread out in all directions, like ripples on a pond.  The picture on the left of the graph on the left shows a limiting case when the jet is not moving at all. As the speed of the aircraft increases, the circles become distorted into ellipses, stretched away from the direction of motion, as shown in the middle picture.  When the jet reaches Mach 1, no disturbances radiate out in front of the aircraft--one major factor in making it stealthy.  No one on the ground hears it until it is "too late".

As the aircraft accelerates beyond Mach 1 (some aircraft can attain Mach 3-4) the circles of disturbance coalesce to form shock waves that stream off the nose and wings of the craft.  When you are on the ground and hear a "sonic boom", these shocks are sweeping across you.  The illustration on the right shows the nose and wing shocks from an F-22.  For stability, the craft cannot fly above speeds that would cause the shock from the nose to intersect the wings.  The shocks from the wing have a different shape than those from the nose because the angle of the wing is different than the angle of the nose, as illustrated in the graph on the right.

How does this tie into geology?  Some fluids, such as boiling water, bubbly magma, and dusty gases have very low sound speeds (here's a pdf of a paper that I published on this phenomenon).  The sound speed of boiling water can be as low as a few meters per second--this means that a fast track athlete could potentially run at speeds greater than Mach 1 if immersed in boiling water! Shock waves would be streaming off that runner like those in the photo above of the F-22!

Another way to envision the aircraft is from the pilot's view: he's not moving, but air is moving past him at Mach 1,2,3 or 4. The same applies to geologic situations.  Imagine that a fluid that has a low sound speed is flowing past an obstacle--a rock or a ridge, for example.  Shock waves will be generated around this obstacle that make the flow field very different from that created by low speed, subsonic fluids.  This fact has been under appreciated in general in the geologic community, and only over the past few decades have studies begun that include the possibility of supersonic flows.  I discussed one observation of shock waves earlier on this blog here.  Shock waves were observed by a number of people during the eruption at Eyjafjallajokul earlier this summer, for example, this You-Tube video.

Happy holidays!!

Thank you all who have logged on in the days since my last post! I'm on an adventure that turns out to have even fewer internet stops than I had anticipated, but have some fantastic geology to share when I return.

Meanwhile, everyone, I appreciate your interest in this site, and Happy New Years to all!

Winter storms in Europe and the Arctic Oscillation

From the Arctic Climatology and Meteorology Education Center
Figure there courtesy of J. Wallace, University of Washington

AO index from 1950 to present
from
National Weather Service
Climate Prediction Center

For several days now flights have been cancelled into and out of many of Europe's major airports.  London's Heathrow and Gatwick have been amongst the hardest hit, Paris Charles de Gaulle is canceling a quarter of the flights today, and Frankfurt is canceling at least 500 of a planned 1300 flights. Airlines are claiming that they haven't seen storms like this in 20-30 years.  What is going on?

Weather in Europe is strongly controlled by a natural phenomenon called the Arctic Oscillation. This is a pattern of pressures over the Arctic.  In a so-called "positive phase" (illustrated on the left of the figure at the upper right) the pressure over the polar region is low and higher pressure in the midlatitudes drives ocean storms toward the north.  In this phase, Alaska, Scotland and Scandinavia have wetter than normal weather, and the US west and the Mediterranean have drier conditions. Frigid winter air doesn't extend as far into North America as usual, which keeps much of the US east of the Rocky Mountains warmer than normal, but Greenland and Newfoundland are colder than usual. Since the 1970's the oscillation tended to be in this phase, which you can see by the dominance of red on the graph to the right.

In the "negative phase" there is relatively high pressure over the polar region and lower pressures in the midlatitudes, but the difference in the pressures are small, that is, the pressure systems are weak. We are now in a negative phase.  The Arctic is warmer than average, whereas parts of the midlatitudes are colder than normal.  The Arctic Oscillation especially affects patterns over Europe, and is the cause of the current blustery weather as well as that in December a year ago. Ironically, the Arctic Oscillation Index went strongly negative just about the time that the 2009  Copenhagen Climate Conference started, causing unexpectedly cold weather there!

For my European friends, stay warm and safe during these holidays!

Book Review: The Planet in a Pebble

Photo Oxford University Press

The Planet in a Pebble: A Journey into Earth’s Deep History

By Jan Zalasiewicz

Oxford University Press, 234 pp.

2010

ISBN 978-0-19-956970-0

$27.95 US

The Planet in a Pebble tells the story of the history of the earth as it can be inferred by a geologist thinking about a pebble. In this sense, the book is evocative of Thomas Huxley, who did the same in 1868 using a piece of chalk. Zalasiewicz, however, uses every method available in the 20^th and 21^st centuries, from the scale and style of field work to the microsopic detail provided by state-of-the art laboratory analyses now available to tell the story. In popular jargon, this is forensic geology. The intended audience appears to be the scientifically literate and interested. Given the state of science literacy in the U.S., this will, unfortunately, be a small audience here.

Zalasiewicz has studied the Welsh slate, a rock that had the “alas, reputation of being wet, grey, and monotonous,” for much of his career with the British Geological Survey, and is superbly qualified to tell this tale. He is the author of “The Earth After Us”, speculations on the state of the planet after humans are no longer a part of it. He is also a gifted writer who clearly loves the language. Two paragraphs from the prologue capture both the essence and the style of the book:

“It is just an ordinary pebble. One of millions that wash backwards and forwards on the world’s shorelines, or pile up on riverbanks or perhaps line your garden path. Yet that pebble, like its myriad kin, is a capsule of stories. There are countless stories packed tightly within that pebble, more tightly than sardines in the most ergonomic of tins.

The size of this story-capsule is deceptive. These stories are gigantic, and reach realms well beyond human experience, even beyond human imagination. They extend back to the Earth’s formation—and then yet farther back, to the births and deaths of ancient stars. Something of the Earth’s future, too, may be glimpsed beneath its smooth contours. Battle, murder, and sudden death are there, and ages of serenity too, and molecular sleights of hand that would make a magician gasp; there are extremes of cold in those stories. And also temperatures that far surpass the heart of our sun.”

Zalasiewicz says that humans love stories, are born storytellers, and he successfully tells a story here. Beginning with a chapter entitled “Stardust,” he introduces the concepts of atomic matter from which his pebble is built, and then moves on to briefly introduce the current structure of the earth’s interior before getting to the core of the book: minerals and sedimentary rocks. How were the Welsh slate pebbles actually formed and how do these pebbles relate to the “deep time” of geology that goes much further back in time than the age of the slate itself (410-570 million years)? He ends with speculations on the future of the pebble, and a nice suggested “further reading” list.

Along the way, he does a nice job of conveying the feeling about what the profession of geology is like, and the nature of the techniques that we use.

My criticisms of the book are truly minor. I was puzzled (as were several colleagues to whom I showed the book) why the front cover had brightly colored pink, grey and white rocks, perhaps even granites or sandstones(?) when the whole theme was the “wet, grey, and monotonous” shale. The back cover and chapter photos certainly show that there are plenty of beautiful grey rocks that could have been featured! If meant to challenge the reader to think about the story in every pebble, it’s too subtle, but perhaps it helps get people to pick up the book because it's more attractive than a collage of grey rocks? I also think that putting the List of Plates right in the front of the book immediately after the Table of Contents was a mistake. These captions are full of technical terms (graptolites, monazite, “tectonically thickened barrel-like mica”) that will discourage any casual reader who is not a geologist from turning more pages. A figure showing the terms used for the geologic time periods would have been helpful.

At this time, when there is such a need for science communication, Zalasiewicz’s contributions and talent are most welcome. I recommend this book not only for the well-told story of earth history, but also for the beautiful writing.

Followup on Pakistan floods

The  floods in Southern Pakistan before (left) last summers major flooding, during it (middle) and this month (right).
Photo collage originally from Modis instrument on NASA's Terra satellite.  This collage from Geology.com.

The NASA image of the September frame, with sites labeled for reference.

When I was first starting this blog, a crisis was developing near the border with China at Attabad, with the potential failure of a landslide dam (here's one blog that I wrote).  These floods that caused the crisis at Attabad moved like a wave from north to south, culminating with flooding near the delta at the bottom of the images (original, higher-quality images are available here). In these images, water ranges in color from light blue to navy; vegetation is bright green--even if it is sparse.  Bare land is beige to red. Clouds are pale green.  Here's another update as of 12/09/10.

The caption released with the images points out several places affected by the floods.  Around Sukkur on the inland side, an irrigation network had supported agriculture.  Floodwaters overwhelmed a dam north of here, creating a flood that inundated this area and dumped water into the preexisting Manchhar Lake.  There is no outlet for this lake, and so the flood waters have sat on the agricultural land for months. Even though the size of the lake has diminished during the autumn months, it is still larger than prior to the 2010 floods (compare the left and right images). Around the coast at Thatta, there is also evidence for lingering damage, with pockets of water remaining in areas which were dry in 2009. Such areas, if stagnant for long, become foci for disease.

The floods themselves were a disaster. The lingering effects such as the drowning of agricultural lands, disease, and dislocation of people from the flooded area are referred to as the "disaster within the disaster". We see how all of these can contribute to political instability in the events that are evolving in Haiti in the wake of the major earthquake there this year.

1859 Solar Superstorm

"The Northern Lights"
Frederick Church, American painter
painted in the 1960's,
perhaps inspired by the 1859 superstorm

I had an earlier post on a the current solar activity in the context of a concern of Newt Gingrich who has made it a political issue. NASA has an interesting blurb today that lays out some of the concerns, and this blog is a summary of that article which puts "The Great Solar Superstorm of 1859" in perspective of the events of the last half of the 20th century.  It includes the following collage of events from past descriptions of superstorms:

"She ran screaming down the street, unable to contain her terror as night was turned into hideous crimson daylight…communications networks failed and equipment burst into flame…a bustling city lost power, trapping thousands of people inside elevators…satellites malfunctioned and in an instant millions of people lost touch with critical services, doctors and children."

From the NASA report cited. Based
on the work of Smart et al.

The 1859 superstorm lasted for 10 days, and is deemed one of the most spectacular solar storms in the past 450 years.  The basis for saying this comes from work by Michael Smart and colleagues who discovered that nitrate concentrations in trapped gases in the Greenland and Antarctic ice crystals rise and fall with solar activity. The graph to the right shows atmospheric nitrate (NOx) abundances from Galileo's time to the present, with the 1859 event highlighted in red.  The article calls attention to the time period during which the satellite industry has based their estimates of "worst case" scenarios: the last part of the 20th century in which there were only two major events, August 4, 1972 and March 1991.  In contrast, since 1561, there have been 19 events more intense than these two, with an average (though nonuniform) interval of 23 years. "The current 40-7ear-0eriod has been the least productive in generating large [events] as far back as 1670 during the Maunder Minimum.  If you wanted to build satellites that endure the rigors of the space environment, Cycle 23 [our last one] and some of the severe storms during the last 50 years, were probably the wrong examples to use as a 'tall pole' for how bad things can get." (I need to update my NASA jargonese, never heard the 'tall pole' analogy before; wonder if goes with their newly discovered sense of drama (the collage above, and sunspot description mentioned below!).


Nevertheless, during Cycle 23, there were satellite outages and losses totaling nearly $3 billion, and commercial satellites collectively lost about 3 years of lifespan at an estimated eventual cost of tens of billions in lost profit.  There were also several near-misses with US electrical grid blackouts.  Those in Quebec who remember the day that the power grid went down in March in Quebec, or those of us who are here in a deep freeze in the midwest this December shudder (literally) at the thought of a length power outage.


If Cycle 24 (the one we have now begun) were to have such a storm, it would be close to sunspot maximum, sometime between 2010 and 2012, likely in March or September during the Equinoxes. If astronomers notice a "large, angry-looking" sunspot (when did NASA start writing poetically?!!) crossing the solar meridian, time to look out.  It is predicted that all satellites on the daylight side of Earth would be blacked out by an intense blast of X-rays and energetic particles.  The X-rays would destroy the D-layer and cause shortwave blackouts; ozone would be depleted by 5-10% causing a spike in skin cancer events.  Auroras would dazzle us around the world. Computer systems on earth would crash as the integrity of their binary information systems is compromised.  Satellite losses and malfunctions would run up to $20 billion losses, Defense Department satellites would be blinded in some ways, and GPS systems would report inaccurately. This would affect precision navigation, oil drilling, search and rescue, and military targeting. 150 million people in north America would suffer a blackout without any precedent. Components of transformers for which there are no replacements would be damaged and have to be manufactured overseas.  The daily cost could be $30 billion in lost salaries, spoiled food, and closures--a larger scale example of the danger of global interconnectedness that the Icelandic volcano Eyjafjallajokull showed us earlier this year.

Rogue wave damages cruise ship

Two days ago (12/07/2010) a cruise ship lost an engine after encountering "monster waves" near the South Shetland Islands north of the Antarctic peninsula. Two videos of the waves are here and here. The ship, The Clelia II, a 5-deck ship, is apparently safe and heading to Ushuia (Argentina), accompanied by an Argentinian naval vessel.  It departed Ushuia for the Antarctic on November 30 and was returning to port yesterday.  The ship is being reported as operated by Polar Cruises based in Bend, Oregon, but Polar Cruises has put out a press release that it neither owns nor operates the ship. It appears that the operator is Travel Dynamics International of New York.. The media is reporting that the ship is carrying 100 passengers and 60 crew members, but several pieces of information in the news conflict with more reliable sources.  According to the International Association of Antarctica Tour Operators, there were 88 passengers and 77 crew.  All of the passengers are from the US. This same ship had an accident Christmas 2009 when a stronger-than-anticipated current pushed it onto rocks at Petermann Island in the Antarctica Peninsula. The starboard propeller struck some rocks, resulting in the shutdown of the starboard engine and loss of electrical power aboard the ship. Damage was significant enough that expeditions were cancelled through mid-January, 2010.

SS Edmund Fitzgerald May, 1975

As can be seen on the video there were heavy seas, and reportedly 55 mph winds northeast of the Shetland Islands. Two ingredients contribute to the creation of rogue waves: strong winds and fast currents. Rogue waves are common in this area of the world because winds have a long interrupted stretch of ocean to blow on the sea surface and build up the waves. For centuries mariners told tales of monster waves up to 100 feet in height.  Mathematical probability theory, however, based on a Rayleigh distribution of wave heights led to conclusions that these waves were unlikely.  A concerted effort to document the waves, including satellite measurements and pressure records from buoys, has now shown that waves exceeding 100 feet are much more common than expected.

Rogue waves also occur on the Great Lakes, and are believed to have cause the sinking of the SS Edmund Fitzgerald in November, 1975. At the time, it was the largest ship (a freighter) on the Great Lakes. The ship sank so quickly that no distress signals were received. When it was located on the bottom later that month, it was found to have broken in two. One theory is that it was hit by the "Three Sisters", a name for the phenomenon that these rogue waves occur in sets (there is a hint of that in the videos above of the recent episode in the Antarctic).  "The Wreck of the Edmund Fitzgerald" was a 1976 hit song by Gordon Lightfoot.

Beautiful, beautiful volcanic picture!

Klyuchevskaya Volcano, December 4, 2010 as observed by the Advanced Land Imager (ALI) aboard Earth Observing-1 (EO-1) satellite. You can link to a high resolution image that covers a larger area here.

This is one of those "worth a thousand word" pictures.  Rarely have I seen a photo in which the atmosphere is so clear around a volcano, the winds are so calm, the lighting is so perfect, and the eruption so striking.  No scale is given for this particular photo, but it is one of a series that have been rising to nearly 8 km (26,000 feet) from Klyuchevskaya.  Perhaps even more striking than the plume is the beautiful collar of pileus clouds surrounding the higher flanks of the mountain. Pileus is the Latin word for "cap". They form when updrafts push up moist air from lower altitudes.  In rising, the air cools to its dew point, causing droplets to form and create the cloud. Pileus clouds often form over cumulus clouds, and over rising plumes themselves as shown in this post about the eruption of Sarychev Peak volcano.

Volcanic plumes have two parts. Near the vent from which they emerge, the ascent of the plume is driven by momentum.  Further away from the vent, the plume rises buoyantly, and at high elevations (not shown here), some plumes form an umbrella. My guess is that this one did not. Plumes transport volcanic ash.  Near the plume, the primary control on ash dispersal is the plume itself--it's momentum and buoyancy characteristics and, to some extent, its interaction with the atmosphere as air is entrained into the eruption column.  Further away from the plume, atmospheric structure and winds control the dispersal of ejecta.  An excellent reference on volcanic plume dynamics is "Physics of Explosive Volcanic Eruptions", Special Publication 145 of the Geological Society of London, edited by R.S.J. Sparks and J.S. Gilbert, 2002.

Cold Lahars Displacing People at Mount Merapi, Indonesia

Dredging in the Code River, Yogyakarta
Photo from here.

Eruptions at Mount Merapi, discussed here, here, and here before in this blog, produced ash and other debris that sits atop the mountain awaiting the monsoon rains. Those rains have arrived; the wet monsoon season in Indonesia lasts from November through March. For weeks muddy torrents have been flowing down from the mountain. On November 30 an apparently big one, reported to be up to 2 meters deep, arrived. According to the Nov. 30 edition of the JakartaGlobe, thousands of residents were forced to evacuate. These muddy flows of volcanic materials are termed "lahars", and they can be either hot or cold depending on the timing of the volcanic activity and the weather.

The lahars flow down the channel of the Code River, which flows through the center of Yogyakarta.  The river has been channelized to control the path of the lahars, a historic danger from Merapi. Sandbags up to 1 meter high help control the flows, but authorities have warned residents that these temporary levees will not contain the large flows that are likely to occur.  Surono, the head of the Volcanology and Geological Disaster Mitigation Agency (PVMBG) has warned that people should stay 300 meters away from the river.  Evacuation has been hindered by damage to roads and bridges, as well as by heavy traffic from people coming in to see the disaster.

An interesting side-bar mentioned in the DredgingToday.com article linked in the figure caption is that the dredging of the Code River has been hampered by the lack of heavy machinery.  However, people living near the river have been helping by manually carting material away.  Apparently it is well known that the volcanic mud is rich in nutrients, and a truck of this material is fetching 50-60 thousand Rp! (50,000 rupiahs convert to about $5.50 US.)

Cold winds, ancient life, and fossil preservation

Sea scorpion fossil from the Soom Shale,
South Africa, ~440 m.y. old
Credit: Univesity of Leicester, as reported
in ScienceDaily, 11/29/2010

Schematic diagram of possible origin of the Soom Shale
from Gabbott et al., 2010, ref. in text

The Soom Shale in South Africa is rich in well-preserved fossils, and geologists have wondered both why they were so abundant, and why they are so well-preserved. In some fossils, you see not only the bone structure, but muscles, gills and swimming paddles.  The answer appears to lie in the story of fierce winds pouring off an ancient glacier, presented in a paper in Geology this month (Gabbott, S.E. et al., Eolian input into the Late Ordovician postglacial Soom Shale, South Africa, Geology, 38(12), 1103-1106.)

During the Hirnantian glacial event, a 1-2 million year event at the end of the Ordovician period which extended from 490-433 million years ago, ice built up over the primitive continent of Gondwana.  his was a period of diverse marine invertebrates and early vertebrates. The ice sheet collapsed rapidly at the end of this time, producing a variety of glacial deposits,topped by the Soom Shale, a 10-15 m-thick black shale. The demise of the marine communities at the end of the Ordovician is widely viewed as the second most devastating extinction to marine life in the history of the earth, and the third largest of the five major extinctions. T Sarah Gabbott and colleagues analyzed thin sections of the shale and found that it contains coarse silt and fine sand in discrete layers (laminae) that are associated with organic material derived from plankton.  They concluded that the geologic setting resembled that found today on the McMurdo Ice Shelf in the Antarctic.  Dust, carried by fierce glacial winds, blew off the ice shelf and into the sea where it fell through the water column.  It carried nutrients that stimulated the production of phytoplankton, which sank to the bottom. In a press release, Gabbott speculated that not only did the nutrients fuel life, they preserved it well when the rotting carcusses sank into the cold, stagnant depths.  "A cold wind, here, was key to both life and death."

A few terms: plankton are the organisms that drift in the oceans, seas or bodies of fresh water.  There are three primary groups, defined according to their function: phytoplankton that use light for photosynthesis (a "producer"); zooplankton that feed on the phytoplankton (a "consumer"); and bacterioplankton (a "recycler"), which basically recycle the other two types of plankton.

Related posts on this blog: katabatic winds and icebergs,
katabatic winds and Mars.

Coal Mine Explosion in New Zealand

The entrance to the Pike River Coal mine.  Photo/NZPA
published by the nzherald.co.nz, Nov. 19, 2010

On November 19, 1 man was killed and 27 miners are missing due to an explosion in the Pike River coal mine on the south island of New Zealand.  The mine has been under development since the 1970's, and is excavating from the largest hard-coking coal deposit in New Zealand. It is in an environmentally sensitive area, and has been lauded as an exemplary development in a sensitive area.  The tunnel, seen at the left, goes nearly 2.5 km nearly horizontally into the mountain.  The trapped miners may only be a few hundred feet underground.

From this Wiki site

Dangers in coal mines arise from at least three factors: the presence of both methane and carbon dioxide gases, and coal dust.  In this particular area of New Zealand, active faults produce a seismic risk as well.  Other causes of accidents are rock bursts, collapse of natural or artificial pillars, flooding, malfunctioning of equipment, and improper use of explosives in the mining process.  Methane gas is nasty stuff: an asphyxiant, flammable and potentially explosive.

The combustion of methane, CH4, is exothermic.  When combined with two O2 molecules, it decomposes to form CO2 (gas) and 2 H2O (liquid) molecules, releasing 891 kJ of energy. It is both flammable and explosive.  When mixed with oxygen and nitrogen in air in certain mixtures (orange region on the ternary diagram to the right), it will explode. The blue line represents air. If there is less than about 5% methane in the mixture it is too lean to explode (the LEL point on the diagram), and if there is more than about 15%, it is too rich to explode (the UEL point).

The process of mining coal generates an enormous amount of coal dust.  When high concentrations of this are suspended in air, and there is even a small ignition source, the nearly instantaneous reaction of the fine coal particles with oxygen can produce an explosion.  The ignition source does not need to be a flame; it can be an electrostatic discharge, friction, or sparks from machinery.  Dust explosions are not restricted to coal mines, but have occurred around grain silos, flour mills, and metal works (aluminum, titanium).  They are intentionally part of thermobaric weapons; see my older post here.

Degassing of Comet Hartley 2--Geysers causing a cosmic snow storm!

Images from the HIgh-Resolution Imager on NASA's EPOXI spacecraft.
Credit: NASA/JPL-Caltech UMD
More images can be found at http://epoxi.umd.edu/

In this amazing image released this week by  NASA's EPOXI mission, two different dynamic processes are shown.  The tiny (~0.93 mile length) peanut-shaped object is Comet Hartley 2. (It's actually being described as more like a drumstick with knobby ends than a peanut.) The images, in different infrared wavelengths, show the distribution of water vapor, dust, CO2, and ice crystals around the comet. The NASA press releases   emphasize that the difference between the smooth and rough areas on this comet are associated with the a difference in the erupting gas: water vapor from the smooth central section, and CO2 from the jagged ends of the peanut. From press articles, it appears that Hartley 2 is producing about 200 tons per second of water vapor; the flux of CO2 has not been estimated as far as I can tell. The H2O vapor production rate is comparable to the rate estimated for production by the plumes at the south pole of Enceladus, an active satellite of Saturn.

Artist's conception of degassing on Comet Hartley 2.
NASA/JPL-Caltech/UMD/McREL

An analysis of the dynamics of the jets as geysers erupting into a vacuum can be found in Yelle, R.V., Soderblom, L.A., and Jokippi, J.R., Formation of jets in Comet 19P/Borrelly by subsurface geysers, Icarus, 167, 30-35, 2004. Their proposal is that there are cavities in the subsurface of the comet that have nozzle-like outlets to the vacuum of space.  As gas flows from a cavity through a narrow nozzle, the flow becomes collimated, and focused jets such as those observed in these images are produced.  Dust is entrained in the gas flow and is accelerated out into a fairly linear jet.  When the gas leaves the cavity, it expands laterally because of the high overpressures compared to the vacuum of space, but the density drops so rapidly that the dust grains that it has been carrying continue on their collimated trajectories, decoupled from the gas.  The result is a diffuse gas cloud with collimated beams of dust or ice. This appears to be the first time that it's been shown that sublimation of subsurface carbon dioxide drives the outgassing of a comet's nucleus.

Other articles of interest: Emily Lakdawalla writes The Planetary Society Blog and has a nice essay describing the features on the comet.

Football can be dangerous...in more ways than expected!

A shelf cloud. Photographer: Jake Deremer.
 Source http://epod.usra.edu
on November 18, 2010.

A wonderful source of potential topics and images for this blog is Earth Science Picture of the Day at http://epod.usra.edu, which is where I found this great photo today.  This photo was taken at a football game between Kansas State University and the University of Central Florida on September 25, 2010 and, as far as I can tell, even though it looks somewhat like a watercolor painting, it has not been Photoshop'd!  Due to the danger of lightning and damaging winds, the football game was suspended for about 90 minutes.

from this WWW site 

This cloud formation is a so-called "shelf cloud", a not uncommon cloud in the midwest. Google it and you get a stunning array of images! It is a type of "arcus cloud", a low, horizontal cloud formation.  There are two types of arcus clouds, one associated with outflows of cold air from cold fronts and the other specifically associated with thunderstorms. The type of  cloud shown here is associated with thunderstorms.  The cartoon to the right shows the dynamics leading to the formation of the shelf cloud.  Cold air, descending from a thunderstorm on the left, sweeps out along the ground (blue arrows), displacing warm humid air toward the right.  The warm air rises and droplets of moisture nucleate to form the cloud.  It was named a shelf cloud because of the "uniform flatness of the cloud base region where moist air that usually originates from the lowest part of the boundary layer achieves homogeneous condensation (discussed in Fankhauser, et al., Bull. Amer. Meteoritical Soc., 64(5), 450-462, 1983)." In this photo you can see up under and behind the roll cloud. Note that the shelf cloud is "connected" to the thunderstorm cloud driving the system.

A roll cloud in Uraguay.  Photo by Daniela Mirner Eberl
taken in January 2009.

A bit of practical advice: A shelf cloud precedes a storm. It is generally associated with a squall line, and marks the place where strong winds begin.  Take note and take shelter!

The second type of arcus cloud is a "roll cloud".  These form when cold air from an advancing cold front advances under a warmer humid layer, typically over relatively long distances.  The humid air roles up around a horizontal axis.  These waves are a form of soliton, having a single peak and maintaining the shape as they advance.  Unlike shelf clouds, the roll clouds are not connected to another set of clouds. Note the clear air behind the cloud (to the left).

Why does a geologist care about the Sudan and John Kerry?

from World Book Student

Sudan is an impoverished nation south of Egypt. The Nile river divides the country into east and west, religious agendas divide the north from the south.  Northern Sudan is dominated by an Islamic government and the Arabic language. The south is dominated by Christians and anamists.  Civil wars between Northern and Southern Sudan began in 1955, the year before independence from Anglo-Egyptian rule that had been in place since 1899.  These were fueled by complicated historical events, and fears by the southerners that the north would dominate them after independence. Conflict raged from 1955 to 1972, followed by a 10-year haitus, but civil war broke out again from 1983. Since 1983, civil war and famine have claimed the lives of nearly 2 million people.  From 1989 to 2005, war continued, terminating with the Nairobi Comprehensive Peace Agreement that granted Southern Sudan autonomy for six years, to be followed by a referendum about independence.

This brings us to the present.  Voter registration begins today (November 15, 2010) for the referendum vote, which is to take place on January 9, 2011.. It is being observed by representatives from the European Union.  John Kerry was in Khartoum on November 7 to carry the message from Obama that the US is committed to peace and to the negotiations.  Obama has offered proposals, and there are fairly explicit hints that lifting sanctions on Sudan is on the table.

Why does a geologist care? Oil and water.  70% of the oil in Sudan lies in the south, but land locked southern Sudan has no way to get the oil to market unless it either goes through northern Sudan, or builds alternate pipelines, probably through Kenya.  The north isn't sure that it can survive on 30% of the oil revenues. And, water--the Nile river has headwaters in the south.  Transboundary water issues may become increasingly frequent in the 21st century as it becomes the so-called "new oil."  Tension is present between the US and Mexico because of the trans-boundary Colorado River, and Bangladesh has over 50 rivers that begin in India or Myanmar. 17 countries share the Danube, 11 share the Congo and Niger, 10 share the Nile, 9 share the Rhine and Zambezi, 8 share the Amazon and Lake Chad, and 6 share the Aral Sea, the Tigris and Euphrates, and the Volta. These and other data are available here.

Solar activity (and Newt Gingrich)

The dark area spanning the equator of the sun slightly to the right of
center on this photograph is a large coronal hole, from which high
energy charged particles started streaming from the sun on November
14.  Photo credit: SDO/AIA.

On Friday, November 12, this sunspot erupted producing a solar flare
that ejected material toward the earth.  The material is expected to "deliver a
glancing blow to Earth's magnetic field sometime on Nov. 14th or 15th."
Photo credit SDO; can be obtained here.
CLICK ON THE IMAGE TO SEE A MOVIE  

After a sluggish start to the current active phase of the solar cycle, the sun is now developing some active sunspot groups.  The sun has a high-density core at a temperature of over 13 million K extending to about 0.25 of its radius.  above this, extending to about 0.7 solar radius is a so-called radiative zone where heat is transported by radiation.  This is surrounded by an outer layer heat is transported by convection of hot material to the surface. The visible surface of the sun is called the photosphere.

Sunspots are regions of strong magnetic activity which reduces convection of energy from the interior to the surface. As a result, they are cooler than other areas of the sun--a mere 3000-4500 K in contrast to the surrounding material at about 5,780 K.  The magnetic field causes strong heating in the corona--the extended atmosphere of the sun.  These active regions are the source of solar flares and "coronal mass ejections" (CME's), emissions of matter, magnetic fields and electromagnetic radiation.  It is believed that the ejections are caused by magnetic reconnection--the rearrangement of magnetic lines of force when two oppositely directed magnteic fields are brought into proximity.  The rearrangement releases energy that was stored in the original oppositely directed fields.  The movie at the bottom shows a spectacular coronal mass ejection on October 1, 2001.  The images in the movie were taken by SOHO's (Solar Orbiting Heliospheric Observatory) LASCO (Large Angle and Spectrometric Coronograph) instrument.

There is a Science Daily article on coronal mass ejections here and an interesting article speculating on the effects of charged particles either from a CME or from a nuclear burst on our infrastructures here.  Former House speaker Newt Gingrich, a likely presidential contender, views this as an enormous threat, and it will be interesting to see if he makes it an issue if he campaigns!

Merapi--again! Disrupts Obama visit this week

A village covered with ash from an eruption on
Thursday, November 11, 2010.  Photographer unknown,
source

According to some reports, the death toll from the on-going Merapi eruptions has exceeded 200, and nearly 400,000 people have been displaced from their homes and villages. President Obama visited Indonesia earlier this week, but cut his visit short be several hours so that his plane would not be caught by changing winds.  To date, the eruptions have released about 140 million cubic meters, exceeding the 100 million cubic meters estimated to have erupted in 1872.

In a paper in press for Geophysical Research Letters (now online), Anchukaitis et al. have examined the influence of volcanic eruptions on climate, and arrive at conclusions that challenge the major results from the Global Circulation Models currently used to model climate.  Those models predict that large volcanic eruptions should result in unusually dry conditions through the regions of Asia that experience monsoons. Anchukaitis et al. used two long tree ring-based proxy's to reconstruct moisture patterns. The first was a tree-ring chronology from a long-lived ccypress species in southern Vietnam, and the second is the "Monsoon Asia Drough Atlas", which also includes tree-ring proxies.  These reconstructed conditions indicate that the response to volcanic eruptions is an anomalously wet southeast Asia and dry conditions over central Asia, a conclusion that is the exact opposite of effects predicted by three widely used climate models: CSM1.4, CCSM3, and GISS ModelE. The authors also conclude that strong El Nino and La Nina weather conditions could be important.  Anchukaitis concludes "...that some GCMs do not correctly capture the balance of important coupled ocean-atmosphere processes involved in the response of Asian climate to radiative forcing.  In a press release accompanying the article the authors also caution that the study suggests that proposed geoengineering schemes to counteract manmade climate change with huge artificial release of sulphates similar to those emitted by volcanoes might have complex unintended consequences.

As of this time, volcanologists do not think that the eruption at Merapi is big enough, or sulfurous enough, to affect the climate.

9/11 Waterfall being set up at ground zero

A quick note to the fluid dynamicists: here's a BBC news article and video of a waterfall project being tested at Ground Zero in NYZ. I don't know any of the details, but there's some good footage of waterfalls on that site.  It appears that testing of the waterfalls if just beginning, and so there should be more news soon.

Where did the groundwater in the Pacific Northwest come from?

Dry Falls, a 350 foot high, 3 mile wide group of cliffs
that formed during the floods that scoured the
Channeled Scablands.  Photo from the U.S. Geological Survey,
available here. Dry Falls is ten times the size of Niagara
Falls, and was formed over a short period of time during the
catastrophic Missoula Floods.

Toward the end of the last ice ages, approximately 20,000 years ago, ice plugged several of the rivers that normally drained water from the area we now know as Montana.  Behind the ice dams, a gigantic lake, Lake Missoula formed.  Repeatedly, the ice dams broke and catastrophic flood, with discharges on the order of a million cubic meters per second, raced down old and new channels, flooding parts of Idaho, Washington, and Oregon under hundreds of feet of water in just a few days.

In a new paper, Brown et al. propose that these floods, in spite of their brevity, provided the groundwater that is now present within the aquifers of the Columbia River Basalts that cover the region (Brown, K.B., et al., Isotopically-depleted late Pleistocene groundwater in Columbia River Basalt aquifers: Evidence for recharge of glacial Lake Missoula floodwaters, Geophysical Research Letters, vol. 37, L21402, 5 pp, 2010.).  This region is semi-arid today, and general climate models suggest that it was colder and drier during the Last Glacial Maximum.  The groundwaters have anomalously low del O18 and delD values, and radiocarbon ages between 15.7 and 19.6 thousand years before present, and the authors suggest that they were recharged from multiple pulses of the Missoula flood events.  Several groundwaters have even older radiocarbon ages and may have come from earlier undocumented Missoula flood events.  The mechanism by which aquifers could be charged with such huge volumes of water in times of just a few days, even with repeated episodes, are unknown, but the large depth (366 m) and volume (>1200 cubic kilometers) of the ponds formed during the floods may have helped drive the water into the aquifers.  These waters are important for agricultural and domestic water resources in central Washington, and--like the Great Lakes--may not be replenished under current geological conditions.

Ice stalactite dynamics

An icy stalactite in Oregon Caves National
Monument.  Photo by Phil Lachman
can be found here, where it was
the Photo of the Day on Nov. 8, 2010.

Icy stalactites are basically icicles! They have some characteristics in common with the better-known rocky stalactites and stalagmites  formed out of CaCO3 when water rich in this compound flows into open spaces or caves. Examples of this kind of stalactite are found in the Mammouth Caves, Kentucky.

Icy stalactites have been observed beneath sea ice, e.g., in the McMurdo Sound area of the Antarctic.  The bottom of a sea ice sheet has numerous "disconnected ice platelets protruding downward" (R.A. Paige, Stalactite growth beneath sea ice, Science, v. 167, pp. 171-172, 1970).  This is called the "skeleton layer", and ranges in thickness from a few centimeters up to 60 cm.  Part of this layer consists of freshwater stalactites.  These can extend up to a meter or more below the skeleton layer.  The process by which briny water forms freshwater stalactites is fairly complicated (see discussion in the Paige article above).

Ice stalactites in caves are similar to icicles observed to form on houses and trees in cold climates. In common with CaCO3 stalactites You can see videos of icicles grown under laboratory conditions here. Steven Morris of the University of Toronto has studied the growth mechanisms of icicles in detail and in lab experiments. The basic process involves the slow downward flow of water either into the ocean or into air.  As the water flows, it may cool to form ice.  Latent heat of fusion is given up and must be transported out through the flowing film of water and into the external seawater or air. (In the case of CaCO3 stalactites, CO2 liberated in the process must be transported out through the water film and into the air.)

Two effects operate to produce the rippled texture of icicles.  Latent heat is more efficiently transferred out of the system on the convex protrusions than from the convex indentations, which tends to make the protrusions grow faster than the indentations.  This is the so-called "Laplace instability".  It is countered by heat transfer down the icicle by the flowing water.  Operating together, they produce a remarkable constant ripple spacing of about 1 cm, although the amplitude of the ripples can vary from one icicle to another.

Morris asked: Do the ripples move?  One group of researchers (Ogawa and Furukawa, Physical Review E, October 2002) that developed a physical model for the ripple development predicted that the ripples should migrate down an icicle at about half the speed that the icicle grows.  Another author (Ueno, Phys. Rev. E69 (5) 2004) predicted that the ripples would move up. Morris was able to use edge detection methods on videos of the icicle development to show that the ripples moved upward very slightly.

Mount Merapi and "ash hurricanes"

This image from NASA's ASTER instrument on the Terra satellite shows
a signature of hot ash and gases flowing down the flank of Merapi volcano
as well as a hot spot on the central dome.  Image taken on November 1.

Since the eruption of Mount Merapi started on October 26, 2010,at least 156 people have died (reports are not consistent at this time).  Press reports have told of people dying from burns and ash suffocation, but no evidence had surfaced regarding the cause of the burns and suffocation because bad weather had prohibited direct observation of the volcano.  Now, the ASTER instrument on NASA's Terra satellite has documented that hot pyroclastic flows ("ash hurricanes") have been sweeping down the flanks of the volcano. (A video of pyroclastic flows on Merapi from previous eruptions can be found here by scrolling down the post to the video.) Temperatures of 450-600 degrees Celsius (842-1112 Fahrenheit have been reported by the Indonesian Volcanology Technology Development and Assessment Agency.  I have found a good blog on the Merapi eruption by Erik Klemetti here.

Merapi in eruption; images from
Clara Prima/AFP/Getty Images posted
on Washingtonpost.com.

What drives pyroclastic flows? In the early frames of the video, large boulders can be seen bouncing down the hill side-by-side with the pyroclastic flow.  This indicates that the flow, like the bouncing boulders, is being driven downhill by gravitational forces.  When gravity is the main driving force, hot material generally is confined to a valley--it's running downhill.  It can "run up" and over hills because of momentum--just like a car that loses its brakes at the top of a hill may race downhill and up the other side of a valley--but generally flows given by gravity follow the terrain. In later frames of this video, including a spectacular segment taken at night, you can see that the pyroclastic flows are being generated by collapse of individual pieces of the steep lava dome.  Section after section is peeling off and falling down and, as the sections impact the ground or other collapsing pieces, they fragment to release fragments and gasses that combine to give form the pyroclastic flow itself.  You do not see "blowouts" of gas-rich material in this video.

A more dangerous condition may arise if pressurized gases inside the collapsing dome decompress rapidly, forming blowouts. Jon Fink and I considered some of these conditions in a paper in Nature, vol. 363, pp. 612-615, 1993.  This paper was motivated by the fact that a pyroclastic flow on Mount Unzen on June 3, 1991, killed three volcanologists who were on high ground that had escaped damage from pyroclastic flows earlier in the eruption.  What happened?  We speculated that a section of the dome containing slightly more volatiles than earlier collapsed sections produced a pyroclastic flow that had higher velocities than had been produced in earlier volatile-poor eruptions.  We concluded that velocity excesses of over 100 m/sec could be caused by decompression of gases in such a section.  These flows would not be confined to valleys, such as the flows to date appear to have been at Merapi, but can have broader extent and longer runout distances. The lateral blast at Mount St.Helens was such a blast.

In spite of the inconveniences and economic consequences, it is necessary to evacuate people from areas around the volcanic summit that appear safe based on the trajectories of small, gravity-driven pyroclastic flows, but that may be devastated by more gas-rich eruptions. Reportedly, about 200,000 people have been displaced by the current eruption.