More from Attabad and Hunza, Pakistan

Here's one of the most impressive debris flows ever documented.  The action gets exciting at about 1 minute.  Note the boulders that appear at about 1'20", and think about the Brazil nut effect in the August posts!

Christchurch Earthquake and Liquefaction

A magnitude 7.1 earthquake centered 30 km west of Christchurch, New Zealand, at a depth of 10 km occurred at 4:35 a.m. local time on Friday, September 3, 2010.  Strict engineering codes prevented any loss of life, but damage to buildings and to underground infrastructure was severe.  Strikingly, Christchurch sits some distance to the east of the major active fault on the South Island, the Marlborough Fault Zone, a transform fault like the San Andreas.

Auckland's waterfront is built on reclaimed land, saturated with water, and large sections of the city laid on soft sediments which remained saturated with water from the New Zealand winter. Whole areas of the city were transformed from firm land to muddy sludge. Water from the sediments squirted up through the soil during and after the quake, damaging as many as 9/10 of the homes on the flats. In one relatively new subdivision, Bexley, over 100 new homes were left unhabitable.  Where the water concentrated into small cracks, mud poured to the surface forming mud volcanoes (photo). A video showing the mud and damage from liquefaction is available here, and an explanation of liquefaction is available here.

Brazil nut effect

Have you ever opened a can of mixed nuts and noticed that the biggest ones are on top?  When a can of mixed nuts is shaken, the big ones do migrate to the top. This phenomenon is known as the "Brazil nut effect", because the biggest nuts in a mixed can are called Brazil nuts. Here's a link to a video about this in a laboratory setting.  In "nature", the physics is much more complicated: what if the 'nuts' have different densities (imagine that one is a real organic nut, but another is a lead weight), and the rate and magnitude of shaking changes. Sometimes Brazil nuts could even end up going to the bottom, instead of the top.  However, keep the Brazil nut effect in mind as you watch this incredible video of a mudflow developing in Pakistan ( the most interesting stuff is at 1.5 minutes). Again, as always, thanks to Dave's Landslide Blog for continuous coverage of environmental hazards around the world.

Eyjafjafallajokull summary

Eyjafjallajokull volcano, Iceland, April 19, 2010, ASTER/Terra daytime image.

(Steve Marshak, a professor of geology at UIUC wrote a substantial part of this.)

The eruption of Eyjafjallajokull volcano has captured the attention of the world during the past week, for it has disrupted air travel to or from Europe, and therefore has traumatized transportation links, business, and tourism worldwide.  A worried public wonders why there, why now . . . and how much longer?  A bit of background about the geology of Iceland, and of the style of eruption we are now observing may be of help.

Eyjafjallajokull is a vent along one of the major fissures or gashes that transect Iceland, for this island sits astride the Mid-Atlantic Ridge, the very active boundary between the North American plate (including North America and Greenland) to the west, and the Eurasian plate to the east.  The Mid-Atlantic Ridge is, in geologic jargon, a divergent plate boundary, meaning it is a surface at which two plates move apart.  This movement is accommodated by sea-floor spreading, a process by which new oceanic crust forms by the rise of magma from the mantle below.

Geologists proposed back in the 1960s, that sea-floor spreading takes place along mid-ocean ridge systems and that, through this process, ocean basins grow wider over time and the continents on either side move apart.   A huge volume of geologic data from the sea-floor supports this theory.  For example, the theory predicts that they youngest crust of the Atlantic Ocean occurs at the Mid-Atlantic Ridge, and that the oldest sea floor occurs adjacent to the continents.  And that's exactly what researchers have found. 

In the last few years, careful measurements using GPS (the same satellite-based global positioning system used in an automobile's navigation system) have allowed geologists to see the continents moving in real time—the process of sea floor spreading takes place without a shadow of doubt.  On average, the distance between London and New York increases by about 2 cm (1 inch) per year, about the rate that your fingernails grow, and nothing that humans can do can change that fact.  The sea-floor spreading process may seem really slow, and it is.  But given the vast expanse of geologic time, slow movements can yield great distances.  At 2 cm/year, the Atlantic has widened by about 2 km in the last 100,000 years (the time since the appearance of modern humans), and about 2,000 km in the last 100 million years.   At this rate, the North Atlantic started to open about 180 million years ago—before that time, the Mid-Atlantic Ridge didn't exist and a dinosaur could have walked from New York to London without getting its feet wet.

Most of the volcanism along the worlds 40,000 of mid-ocean ridge occurs at depth 2 km beneath the sea, in utter darkness away from the inquiring eyes of humans.  But research submarines have been able to photograph the consequences of this activity, including fresh lava flows and black smokers, remarkable jets of super-hot water heated by magma (molten rock) below the surface.  Iceland is special — it sits atop a huge plateau of lava, a volume much greater than any other location along a mid-ocean ridge.  For this reason, many geologists have suggested that Iceland is a hot spot, a region where a column of particularly hot rock is rising slowly from great depths in the Earth.  When this rock  reaches the base of the plate, it starts to melt, producing vast quantities of magma, much more than normally occurs along mid-ocean ridges.  As this magma erupts, it built up the Icelandic plateau and eventually emerged from the sea as an island.  But it is not a stable island—as sea-floor spreading progresses inexorably, the island splits along fissures, erupting currents of lava (molten rock at the Earth's surface).  These eruptions drain the supply of magma that accumulated below the island for a while, and when enough of the magma has drained, the eruption ceases.  But just for a while—inevitably, as more magma rises, and as the island slowly splits, an eruption is sure to happen again.

The last really major eruption along the fissure system of Iceland happened in 1783, when Benjamin Franklin was ambassador to France.  The ash affected the climate in Europe that year, causing an overall cooling.  It was Franklin, in fact, who published the first article to suggest a relation between climate and volcanic eruptions.  (The effect he described, significantly, is not the same effect as caused by long-term changes in the concentration of greenhouse gases, such as CO2—volcanic eruptions of the magnitude we're seeing in Iceland, or that the world has witnessed in recent centuries, such as at Krakatoa and Pinatubo, have a fairly short-term impact.  Other ashy eruptions, such as the one of Tambora in 1816, also had global climate impacts—1816 was so wet and cold in Europe that it came to be known as the "year without a summer." It's been suggested that somber climate of the last one inspired Mary Shelley to write Frankenstein)

The fissure came alive again, on March 20, when the volcanic vent called Eyjafjallajokull awakened from repose with an eruption on the northeast flank, in a narrow 2-km ice free zone between it and neighboring Katla volcano[1].  Low fire fountains reminiscent of Hawaiian volcanism burst from a 500 meter long fissure, and a small plume of ash less than 1 km high developed.  This eruption continued intermittently until April 12.

After a very brief repose, magma worked its way into the central glacier-covered crater and a new eruption started just after midnight on the 14^th of April.  A series of vents opened up along a fissure nearly 2 km long.  The intruded magma provide heat to melt the glacial ice, producing floods of water, known as Jokulhlaups, that flowed under the ice toward the southern coast of Iceland. These reached the coast around noon on April 14, destroying roads, infrastructure and farmlands. Icelandic geologists have done a wonderful job of monitoring and forecasting the eruptions, and 800 people were safely evacuated before the devastation hit.

When daylight broke, an eruption plume was observed, reaching more than 8 km height, carrying ash high into the atmosphere where the jet stream was parked over Iceland.  During the first three days, some 70-80 million cubic meters of magma were discharged, at an average rate of about 750 tonnes/second.

The change in eruptive style between the March and April phases of this eruption can be attributed to the availability of water to the magma.  The March eruptions were “dry”, driven only by the fairly minor amounts of gases dissolved in the magma, and by the pressure that squeezes magma beneath upward like bubbly toothpaste being squeezed out of a tube.  In the most recent phase, water from the melting glaciers sank downwards through the ground and came into contact with the magma and surrounding hot rocks.  Where the water only contacts hot rocks, it vaporizes and rises to form billows of white steam.  But where it contacts the magma, it abruptly cools (is "quenched") and the magma, causing it to solidify almost instantly, into glass.  The result produces vast quantities of fine volcanic ash that are then blown out of the volcano in dark roiling ash clouds. In places where the water has contacted the magma, the production of ash exposes more magma to more water and so the process feeds on itself creating more material to that erupts into the plume. 

What does the ash consist of?  Viewed under a microscope, it looks like tiny, jagged flakes and slivers of glass.  Chemically, the ash consists of the same elements that make up the magma—mostly silica (SiO2), magnesium oxide, and iron oxide.  Silica is the same chemical compound that comprises the familiar mineral quartz, which when melted and quenched produces window glass.  Ashy, steamy eruptions such as the one now occurring in Iceland are called phreatomagmetic eruptions, meaning that the eruption is driven not only by magma with its dissolved gases, but surface waters (the “phreato” part of the word).  In this case, the surface waters are being produced by melting of the ice cap on top of Eyjafjallajokull.  The combination produces very explosive eruptions and is one reason that Iceland carries the nickname “Land of Fire and Ice”.

Winds carried the ash toward Europe where it arrived on April 15, causing the closure of air traffic throughout Scandanavia and northern Europe. Unusual stagnant high-pressure conditions in Europe have prevented the ash cloud from dispersing, causing continued air transport and economic problems in Europe. The ash plume activity Ha continued to the present, with an average height of 5 km and pulses to 8 km. 

When the magma fragments into fine ash particles, static electricity builds up on the particles and is then discharged in magnificent displays of lightning.  Recent research suggests that volcanic plumes rotate around their axis, like super-cell thunderstorms.  Due to the rotation, electrically charged ash particles are spun out away from the axis to form a sheath on the exterior of the plume, causing dramatic lightning displays to be concentrated in the sheath. 

How long will the eruption occur?  No one can predict exactly, but careful monitoring will minimize the unexpected. What will the weather be like when the next eruption occurs? No one can predict at all! This eruption was a very small one by global standards, but it occurred just when the atmospheric conditions were right to make conditions in Europe miserable. It is a volcano-weather pattern that is statistically very small.  Seismic activity called “volcanic tremor” now occurring in Iceland suggests that the area is remaining active, at least underground  Only time will tell if 2010 will be another year without a summer.

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[1]Steve, not sure how to cite references. Much of the factual material taken from http://www.evropusamvinna.is/page/ies_Eyjafjallajokull_eruption.  I’m leaving the units in metric until we decide if we’re really doing this.  Much more accurate and easy to check.

Large Landslide in British Columbia, Canada

On August 6, a melting glacier in British Columbia, Canada, was reported to have triggered a massive muddy landslide at 5:30 a.m. Later reports, still somewhat confusing, say that it was actually the Capricorn glacier itself that gave way. The area affected is about 150 miles north of Vancouver, British Columbia.  This is an area of unstable volcanic rocks prone to landslides.  The estimated volume of the slide is estimated to be 40 million cubic meters, and is the second largest slide in Canadian history, the largest being the Hope slide of 1965 that had a volume of 46-million cubic meters.  The new slide is being referred to as the Mount Meager slide.  The slide stopped in the area where Megher Creek intersects the Lillooet River, and temporarily damed the Lillooet.  A temporary lake was formed containing 1.5 - 3 million cubic meters of water, but breached through the dam early in the morning of August 7 (3:00 a.m.)  It cut a breach between 25-50 meters wide (contrast this to the on-going drama at Attabad in Pakistan). Further information is here, as well as more photos. The photo attached was taken by "Bonny Makarewicz, Special to the [Vancouver] Sun", and can be found in the reference cited.

Dam break in Iowa

dam break story
I am on travel and will update this when I return.

Update on Channel Geometry at Attabad

The Pamir Times published a new, but lower resolution photo, of the spillway at Attabad a few days ago.  There has been substantial erosion of the channel in the downstream portions, but it is difficult to tell whether or not the upstream choke point has changed as much. The lake level has been rising in response to the summer runoff season, but has plummeted the past few days.  The reasons are not clear; details and speculations here.  Yesterday, Dave's landslide blog reported that officials in Pakistan have decided to blast the spillway to lower the lake level several 80 meters in order to try to restore the Karakoram highway to China that has been drowned out by the blockade lake.  This is clearly a major, and potentially hazardous, engineering task.

New Video by Nisar Ahmed on Hunza

Official news regarding the Attabad landslide and the situation in Hunza has been slow lately, but a new video by a local director provides both a historical perspective, spectacular scenary about the valley, a documentary of its people, and a political perspective on the situation of the humanitarian crisis. The people are long-lived, and have a nearly 90% literacy rate. I had not realized that the people noticed cracks in the ground in 2002, the government had apparently declared a red zone, but done nothing to enforce it.  More than 25,000 people have been displaced since January 4.  The lake is currently about 27 km long, inflow about equals outflow during this high season of the melting and runoff. I highly recommend this video for witnessing the courage of an incredible people in the face of an ongoing natural disaster and humanitarian crisis.

Decision to Blast at Attabad

Dave Petley reports that there has been a decision to blast out some of the rocks in the channel at Attabad, but there is no information about which boulders are to be blasted. The large "boulder" at the top of the spillway is shown at the right. There has been considerable erosion around it in the past few days.  For those who raft in the Grand Canyon, the image conjures up nightmares of the bad waves of Lava Falls in the Grand Canyon!

There is, however, a second big boulder downstream and it's not clear to me that blasting the first one will do anything but move the choke point downstream to this boulder.

Update on Attabad

The frustrated displaced people at Attabad have begun taking the situation into their own hands, returning to the landslide and trying to widen the channel by hand as shown in the photo.  This is an extremely dangerous situation, not only because of the ever-present dangers of landslides but because removal of material at the toe of the sides of the channel can destabilize it and cause collapse onto the workers.  The Pamir times describes the social unrest and conflict with authorities as this unfolds.  It also has a gallery of pictures of the work.


An indication of the social situation is a quote from the Home Secretary "Those widening the spillway are agents of the enemies of Pakistan."


Dave Petley has obtained information from David Archer (University of Newcastle) about the annual discharge patterns at the village of Dainyore, downstream of Attabad, where there is a hydrograph. From Petley's site on June 17:


Flow                         Mean date                                 Standard Deviation (days)
Peak                         29th July                                   14
50% of peak             26th June                                  11
20% of peak             3rd June                                    9
10% of peak             18th May                                  11
5% of peak               2nd May                                    9


Since we are about half way between June 3 and June 26, this suggests that the spillway is currently only experiencing 20-50% of the peak discharges, and that the flow will increase inexorably over the next month.

More on the Oliver, British Columbia, landslide

Photograph from the Oliver Daily News, June 17, 2010.
Also on Dave's Landslide Blog on the same day.

New air photos posted on Dave's Landslide Blog show that the landslide in Oliver last Sunday was triggered by the overtopping and eventual failure of a small earthen dam high up in the catchment basin.  Rural areas all over the world are littered with these earthen dams (simply piles of soil) and many are old ill-maintained.  In this case, hikers had warned authorities two days prior to the failure that the lake behind the dam was overflowing.  The dam subsequently failed through the breach shown in the center of the upper photograph. Authorities did not warn those downstream, and there are now demands that there be compensation. An investigation is underway.

In other news today, a wall in a mining pit in Tasmania collapsed, creating a huge rockslide.

And, I've found another very interesting landslide blog in Darjeeling, India, "Save the Hills".

Katabatic Winds and Icebergs

Image from NASA's MODIS on the Aqua satellite, taken March 11, 2010. Image is true-color.

Strong winds can occur when cold dense air descends down a glacier or ice sheet.  The winds can be hurricane speed, but more commonly are about 10 knots.  These winds are variously termed katabatic, gravity, or mountain winds.  The name originated from the Greek word katabatikos, which means "going downhill." In the Antarctic these winds then blow across the ocean water, producing ice crystals on the surface (the blue-gray areas of the photo in the area labeled "Southern Ocean).  The winds are moving from the lower left toward the upper right.  The winds then push the newly formed sea ice toward the north.  Drifting icebergs (the bright white fragments) interrupt the flow of the winds, blocking the ice formation in small areas on their leeward sides (dark areas are open water).  Related article at NASA Earth Observatory.

World Record for Mentos-Diet Coke Geyser Eruptions

For the past two years there has been a craze amongst students to set world records for eruptions caused by mixing Mentos (mints) and Diet Coke.  On June 6(?), a new world record was set by students at Changchun University. Clothed in blue raincoats (provided by their University!), they set off 2,175 simultaneous eruptions, shattering the two-year old record of 1,360 set by students in Belgium.  (I may not have the previous record correct.)

The geyser eruptions are triggered when Mentos are dropped into the Diet Coke.  The rough surface of the Mentos triggers nucleation and growth of bubbles of carbon dioxide (CO2), and the expansion of the gas drives the foamy mess out of the Coke bottle.  Diet Coke is the preferred beverage because it's not as sticky as the other options when it sprays all over the place!

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Nozzles and Debris Flows

Image from The Province.

The town of Oliver in the Okanagan, a rural area of British Columbia, Canada, was hit by a mud and debris flow yesterday, June 13.  This flow originated in an incised canyon where Testalinda Creek flowed from a lake.  Five homes were swept off their foundation, there were no injuries.






As pointed out on Dave's Landslide Blog (on June 14), Oliver sits on a small debris fan, shown as the triangular area just above the highway 97 sign in this photo from Google Earth (click on the photo to enlarge it so that you can actually see the debris fan). Upstream from Oliver is a lake, drained by Testalinda Creek which flows in a deeply incised canyon.  In such situations, debris can build up at the bottleneck in the canyon to effectively form a dam. When rain has saturated the soil, as has been the case this rainy summer, the debris pile can let loose and send a torrent of water, mud, and debris out into the surrounding country side.

Thar' She Blows!!

Sand volcanoes are perplexing features.  In researching them this morning, I came across an amazing video--a movie of a sand volcano in the making.  It's on U-tube, little documentation, so I don't know if this is actually a drilled well that is blowing sand out, or if it's natural. (You may need to search around on the linked page to make the video work, but it's an interesting page to explore anyhow!)  The comments posted with it say that this is a "sand injective" or "sand volcano" taking place by the side of the road in Saudi Arabia.  It was taken on a mobile phone and posted on YouTube, original user unknown.  A recommended reference on sand inectites is Hurst, A. and Cartwright, J.A., 2007. "Sand injectites: implications for hydrocarbon exploration and production. AAPG Memoir, Tulsa, 274 p.

Hare Ball!

Time magazine on-line posted 12 photos from an "art in science" competition today, and I found this one to be really neat! It's a desert hare struggling to stay warm on a cold morning (left) by closing down into a position that minimizes the surface to volume ratio and preserves body heat.  When the sun warmed him up (right) he resumed the more normal position in which his large ears and extended limbs can function to get rid of the excess body heat normally encountered in desert environments.

Erosion in Action at Attabad (video available)

Photos of the situation at Attabad on June 7 (left) and June 8 (right).  The rate of erosion of the spillway has diminished during the past week as flow out of the lake now equals flow into the lake.  However, the melt season has not yet begun and discharges will have to increase over the summer.  Apparently authorities are contemplating whether or not to dynamite the region at the top where a large boulder constricts the flow.  Such a move would be very controversial and potentially dangerous, with the possibility of triggering more landslides in this area very real.  One hazard now is that a landslide into the lake will cause overtopping of the spillway and rapid erosion.



There is a new video of the river cutting through the landslide at Attabad.

Jupiter hit Again!

Processed image by Anthony Wesley, Broken Hills, Australia

It was initially a bit difficult to track this one down, but two amateur astronomers caught an impact on Jupiter on video.  A report from the Philippines said that the impact was around 4:30 a.m. on Friday, June 3.  The other amateur astronomer who captured this on video was the Australian, Anthony Wesley, who caught the 2009 impact. The Philippino, Christopher Go, estimated that the fireball flash lasted about two seconds.  His story is nice--a guy whose imagination was fired up in 1986 by Halley's Comet.  Now 39, he continues working from his home. He discovered the second red spot on Jupiter known as "Red Jr."  It appears that credit for the discovery will go to the Anthony Wesley and that Go's video will be the confirmation.


The impact flash is the white dot at 4:00 in this image.
The video and more details can be found here.

Asteroid (?) Slams into Jupiter

Photo from NASA press release.

On July 19, 2009, an object struck Jupiter, leaving a scar the size of the Pacific Ocean.  This is not the first time that impacts on Jupiter have been observed.  During the same week, 15 years earlier, pieces of Comet Shoemaker-Levy repeatedly hit the planet.

The elongated shape of the impact site suggests that the impact was from a relatively shallow angle.

By comparing images of the 1994 comet impact and the 2009 impact, astronomers noted distinct differences.  In the 1994 impact sites, ultraviolet images from the Hubble spacecraft showed a distinct halo around the impact sites.  This was interpreted as evidence of fine dust arising from the (dusty, icy) comet as it impacted the atmosphere of Jupiter.  In contrast, the 2009 images show no halo, suggesting a lack of fine particles.  The 2009 impact site disappeared much more rapidly than the 1994 site, and this has also been taken as evidence for a lack of fine particles.  The implication is that the impact may have been by a solid, rocky asteroid rather than a dusty icy comet. 

This study appeared in the June 1, 2009, issue of The Astrophysical Journal Letters.  

More detailed press release.

Gas Blowouts and Tornadoes near my Hometown, Western Pennsylvania

The role of noncondensible gases in the blowouts of geothermal and hydrocarbon wells is not widely recognized. Here's a most recent event of one near the town of my birth.  Here's the next day's notice of severe weather! Gee, when we were kids we never had any clue that life was so exciting there!

The BP Well Operation and Their Problem with 'ice' Clogging

Image source: unknown

British Petroleum engineers have successfully installed a cover on the leaking well and are trying to siphon oil to surface ships.  They have been proceeding cautiously because their previous attempt with this procedure got clogged with a nasty form of ice called "methane hydrate" or "methane clathrate".

Water ice is capable of absorbing an amazing amount of some gases into its structure in "cages".  A typical clathrate cage is shown in the inset of this image of a methane clathrate burning.  Yes, you can set ice on fire!. The gas burns off leaving the ice structures behind. The gas molecules are stored in cages of H2O molecules, and it's quite amazing how much gas can be stored in these cages.

Clathrates are a major reservoirs of natural gas globally, as shown by the map of clathrate deposits.  The dissociation of this weird form of ice has been implicated in everything from the disappearance of ships in the Bermuda Triangle to sudden climate change.  It's been proposed that sudden "burps" of methane gases from clathrates in the Bermuda Triangle have changed the density of the water column so that ships that were floating on the water suddenly found themselves floating on "gassy water" and lost buoyancy, sinking to the bottom. (One thing nice about this blog is that I don't have to provide rigorous referencing!!)  55 million years ago, the Paleocene/Eocene boundary, there was a dramatic climate change that some have argued was due to a sudden methane influx into the atmosphere due to decomposition of clathrates.  The cause of decomposition is unknown, but theories relevant to the current climate crisis are abundant.  I found this article by Galvin Schmidt to be a thoughtful analysis.

Attabad Landslide Videos; Gulf Oil Spill update

Graphic from Dave's Landslide Blog.

Reuters has finally picked up on this situation with some statistics about the number of people displaced and villages at risk.

Events are progressing rapidly on two issues that I've been tracking.  At Attabad, the flow rate over the spillway has increased dramatically (the last data point on the upper right), suggesting a change in the spillway conditions. No photography is yet available. A friend pointed out two videos of interest.  The first is a short and haunting documentary about the conditions in the Hunza Valley--I had not realized that the main road for transportation of goods into China was cut off by the slide. The second is an eyewitness video of the landslide itself. It is amazing to see how long the slide took to be deposited, and also amazing that the photographers didn't start getting out of there!

UCAR has just issued a simulation of the movement of the Gulf oil slick.  The broken BP well is in a relatively stagnant region of the Gulf and so it has been spreading slowly.  Once it gets into the Loop Current, it accelerates to 40 miles per day, and then once it moves around Florida and enters the Gulf Stream, it is projected to reach speeds up to 100 miles per day.  It may reach as far as Cape Hatteras before turning out to the Atlantic.

Gulf of Mexico Natural Oil Seep Rate vs. Deepwater Horizon Seep Rate

Photo from BP via Reuters, published in NYTimes.com on June 2, 2010

I will rarely post a fairly lengthy direct quote here, but this one is worth it and from an expert, Cutler Cleveland. He was a student of Bruce Hannon's here, and is a professor at BU. We used his sustainability text in our sustainability course.

First published in the Encyclopedia of Earth
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"Some reports in the media attempt to downplay the significance of the release of oil from the Deepwater Horizon accident by arguing that natural oil seeps release large volumes of oil to the ocean, so why worry? Lets look at the numbers.


Natural seeps can be thought of as natural springs from which liquid and gaseous hydrocarbons (hydrogen-carbon compounds) leak out of the ground. Oil seeps are fed by natural underground accumulations of oil and natural gas. Satellite images have identified hundreds of areas where oil is likely to seep from the Earth's crust into the waters of the Gulf of Mexico. These seeps occur over a wide range of the 615,000 mi² (1.6 million km²) Gulf. A 2003 study by the National Research Council and a 2009 report by oil spill expert Dagmar Schmidt Etkin indicate that between 560,000 and 1,400,000 barrels per year (1,534 to 3,835 barrels per day) seep into the Gulf of Mexico from natural sources. Dozens of natural seeps have been identified off the coasts of Louisiana and Texas, some in the region of the Deepwater Horizon site.


These natural seeps are quasi-continuous or chronic inputs that represent a "background" rate of oil input that have been in existence for hundreds or thousands of years. As the term "seep" implies, the rate of oil release from these sources is much smaller than human spills that often release large, concentrated pulses of oil. One of the largest and most intensively studied seepage areas lies off Coal Oil Point, in Santa Barbara County, California. Individual seeps in this area release an estimated 80 to 100 barrels (3,360 to 4,200 gallons) of oil per day; Deepwater Horizon is releasing 12,000 to 19,000 barrels per day.


The Deepwater Horizon site releases 3 to 12 times the oil per day compared to that released by natural seeps across the entire Gulf of Mexico. By May 30, the Deepwater Horizon site had released between 468,000 and 741,000 barrels of oil, compared to 60,000 to 150,000 barrels from natural seeps across the entire Gulf of Mexico over the same 39 day period.


Natural seeps are not constantly active; the volume of oil released can vary considerably throughout the day and from day to day. As a result, only a small area around the source is actually exposed to "fresh" non-degraded oil, which is its most toxic state.


Marine and coastal organisms and ecosystems presumably have adapted to the natural rate of oil input. Indeed, most organisms living in the regions near natural oil seeps have no special adaptations to the oil. Researchers at Woods Hole Oceanographic Institute and the University of California/Santa Barbara studied natural seeps off the coast of California. They found that as the oil moved upwards in the water column, a wide range of microbes consume the oil and produce intermediate products, and that those intermediate products are then converted by another group of microbes to natural gas and other compounds. Their research suggests that oil from natural seeps normally stays in the water for between ten hours to five days.


Oil that does make it to the surface from natural seeps can spread out very widely. One gallon of oil can spread out to cover more than a full square mile, forming an extremely thin film on the surface, about one-hundredth of a millimeter thick. Under these conditions, the oil is not hazardous. Some of the oil in that thin sheen evaporates within seconds or minutes after it reaches the surface.


A sudden, concentrated and massive pulse of oil from an event such as the Deepwater Horizon disaster presents a fundamentally more acute stress to marine and coastal systems. The amount, rate and spatial concentration of crude oil released from such an event overwhelm the natural mechanisms of oil dispersal and breakdown, producing the significant ecological effects that we observe."

Cutler J. Cleveland
Boston University
May 31, 2010
http://www.eoearth.org/article/Deepwater_Horizon_oil_spill

References


Clester, S.M., J.S. Hornafius, J. Scepan and J.E. Estes, Quantification of the relationship between natural gas seepage rates and surface oil volume in the Santa Barbara Channel, EOS Transactions of the American Geophysical Union 77 (1996), p. 420.


Cutler J. Cleveland (Lead Author); C Michael Hogan and Peter Saundry (Topic Editor);. 2010. "Deepwater Horizon oil spill." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth May 24, 2010; Last revised May 30, 2010; Retrieved May 30, 2010]

Farwell, Christopher, Christopher M. Reddy, Emily Peacock, Robert K. Nelson, Libe Washburn and David L. Valentine, Weathering and the Fallout Plume of Heavy Oil from Strong Petroleum Seeps Near Coal Oil Point, CA, Environ. Sci. Technol., 2009, 43 (10), pp 3542–3548.

National Research Council Committee on Oil in the Sea. 2003.Oil in the Sea III: Inputs, Fates, and Effects. National Research Council Ocean Studies Board and Marine Board Divisions of Earth and Life Studies and Transportation Research Board. National Academy Press, Washington, DC, USA. 265 pp.

Schmidt Etkin, Dagmar, Analysis of U.S. Oil Spillage, API Publication 356, American Petroleum Institute, August 2009, Washington, D.C.

Wardlaw, George D., J. Samuel Arey, Christopher M. Reddy, Robert K. Nelson, G. Todd Ventura and David L. Valentine, Disentangling Oil Weathering at a Marine Seep Using GC×GC: Broad Metabolic Specificity Accompanies Subsurface Petroleum Biodegradation, Environ. Sci. Technol., 2008, 42 (19), pp 7166–7173.

Attabad, landslide dam failure imminent(?)

Dave Petley continues to inform the world of the events at Attabad. Compare this image of the situation yesterday with the photo below of the situation today. It is helpful to locate a few markers: (1) the white rock projecting toward the waterfall from a position just to the right of the low point in the road at the top of the photo; (2) the prominence at the top left where it looks like a large rock sticks out into the lake just where it starts flowing into the spillway, and (3) two large rocks on the slope on the left side of the steep waterfall. The upper rock closest to the water is grey with a white "nose", and the other rock (directly below it in the photo) is flat and white. (4) There is also a convenient marker, a black vertical line toward the bottom center of the photograph.

Using these markers, you can see that the water from the lake is accelerating toward the waterfall just above the "grey" rock. The waterfall over the steepest part of the slope is turbulent, frothy, and has no exposed rocks to speak of. The gully at the bottom of the waterfall is an area of erosion. Compared to the next photo taken at a slightly different angle, the water disappears behind a ridge, but it's not possible to see what is going on behind this ridge.



Now look at today's picture. For scale, there are two people just above the white marker rock  on the right side of the river.  The upstream conditions where the lake starts to flow into the spillway are about the same, but the situation is changing dramatically between the grey boulder on the right and the pointy rock over by the road. The channel has noticeably widened, exposing rocks in the channel. A critical place to look is at the changes in the channel between the three rocks that I've defined as reference points. It is widening significantly in this area. Dave proposes that the water is now eroding the landslide itself instead of just the spillway materials. He says "The waterfall ....has create(d) a set of rapids that are clearly eroding back up the channel. The head of the rapids are close to the saddle. The key point is probably the location where the channel became notably steeper--this is where scour accelerates. Once this point is reached and passes the saddle, the rate of flow will start to increase and we might well see the breach developing. Unless the top of the rapids is being impeded by a large boulder or similar, this will probably develop quite quickly....downstream communities need to be prepared for a rapid breach."

There are three ways that this channel is eroding: expansion of the width, deepening of the channel by bottom erosion, and retrogressive erosion. I was fortunate enough to be able to document the processes that Dave is describing today in a study of one of the rapids in the Grand Canyon in 1983. A debris flow (technically different than a landslide) roared down Crystal Creek in 1966 and clogged the Colorado River, forming one of the most difficult, and deadly, rapids on the Colorado. Discharges through the Grand Canyon are controlled by the discharges through Glen Canyon Dam. In 1983 a series of events forced the Bureau of Reclamation to increase the discharges to three times the level that had ever passed through Crystal Rapids.

The cartoon on the upper right shows what happened, and happens as floods of different sizes attack barriers such as debris flows or landslides. In the Grand Canyon, debris flows episodically block the path of the Colorado, and so the starting point for the erosion is arbitrary. At low discharges, the river will erode a relatively narrow channel through the saddle point of the debris flow. At the rapids of the Colorado, this saddle point is always on the opposite side of the river from the side-canyon of origin of the debris flow. However, landslides can have such high velocities and so much mass that they shoot across the main river channel and bank up against the far side. In this case, the saddle point isn't necessarily against the far wall as shown here, but can be in the middle or even proximal part of the landslide.

Increasing discharges widen the channel, and scour out the bottom (not well shown in these cartoons). There can also be erosion through the debris flow either from the upstream side (not likely in most cases because flow velocities are low on the upstream side) or the downstream side. The latter is the regressive failure, also called headward erosion, that seems to be dominating at Attabad.

When the headward erosion reaches the saddle point the floor of the channel will be dramatically lowered at this critical point. Water velocities will increase causing erosion to increase, and this is the time when the landslide lake may pour out and into the valley of the Hunzen River.

We who are watching this unfold hope that the people of the Hunza Valley are safe.

Kung Fu Bear!

Sometimes it's just worth taking a break from normal science and watching something captivating. A short version of this video of a bear affectionately named "Kung Fu" was circulated the past few days, drawing a lot of press coverage. The controversy was whether or not this is all a fake. This video is a longer, edited version put out to prove that this bear and his act are real! Maybe we tool-wielding homo sapiens evolved from bears? Go, Kung Fu Bear!!

Water flowing through the spillway at Attabad

On May 29 water started flowing through the spillway at Attabad. The photo here, from Dave's Landslide blog, shows an early stage of the overtopping. The spillway is working well at these low discharges. There were some reports of landslides into the lake today, and estimates that these slides had increased the lake level by 2 feet, but I don't know if these have been verified. As of this a.m. the discharge through the spillway is estimated to be 4 cusecs (cubic meters per second).

The lake level is rising about 2.5 cm per hour, and inflow into the lake is estimated to be 71 cusecs. There is thus about a 7 cusec difference between inflow and outflow. This water is stored in the lake causing its level to rise. As it rises, the discharge through the spillway increases. One limiting case is that the spillway channel will stay at the current width, in which case the increase in discharge is directly proportional to the rate at which the lake level rises and increases the depth of the water flowing through the spillway channel.

At the other extreme, if the spillway erodes and widens, then the discharge will increase as both the area increases and the depth increases. Erosion at the bottom of the channel would increase the depth of the flow through the spillway even further. It is this later case that worries the landslide experts because the discharge could increase so rapidly under these conditions. Dave is updating his blog frequently, so tune in there rather than here!

Tungurahua volcano, Ecuador, closes Guayaquil Airport!

The second airport in two days has been closed by a volcanic eruption. Tungurahua volcano began erupting yesterday, closing the Guayaquil Airport until at least this afternoon. I was in Guayaquil about 10 years ago on my way to the Galapagos and found it to be a very pleasant and undiscovered seaport town.

Pacaya Volcano, Guatemala, is erupting

This photo is from Wiki on May 28, 2010, attributed to the USGS from the site http://www.ngdc.noaa.gov/hazard/slideset/28/28_576_slide.shtml


According to CNN, Pacaya Volcano, 15 miles south of Guatemala City, began erupting at 9:00 p.m. ET on Thursday, May 27. Two villagers and a reporter from a CNN affiliate were killed in the initial eruption, crushed by rocks spewed from the volcano. 1800 people have been evacuated, and the airport in Guatemala City is closed as of Friday. Pacaya was dormant for a century until 1965, and has been active since then. The government has declared a 15 day state of emergency.

Pacaya is a young volcano, dated back to 23,000 years. It lies on the edge of an older larger caldera formed at least 300,000 years ago. It has erupted at least 23 times since the Spanish colonization in the 15th century. It is one of the many Central American volcanoes associated with the subduction of the Cocos Plate beneath the Caribbean Plate.

Eyjafjallajokull is Quieting Down

According to the Icelandic Meteorological Office, the activity at Eyjafjallajokull has diminished in a number of significant ways, although it is not clear whether this is "the end" or just a lull. The plume is "only" 10,000 feet high and is composed of steam only. There are no reports of ashfall, and no lightning strikes have been detected (lightning strikes indicate significant ash concentration). Meltwater from ice surrounding the volcano is small, temperatures from a heat camera are "almost 100 C". Volcanic tremor is decreasing to levels prior to the eruption, except in the frequency band 1-2 Hz which may be due to rising steam. I published a paper ages ago regarding seismicity of a very similar nature at Old Faithful, see Figure 1, reproduced here. It had been noted by scientists studying Karkar Volcano in Indonesia that there was banded harmonic tremor that suggested underground geyser eruptions, and the similarity of the two seismograms (Karkar and Old Faithful) is amazing.

You can get a higher resolution look at the figure by clicking on it, but it's not a high-quality image to start with! I look fondly at the low-quality reproduction of the seismic record (it isn't much better in the pdf of the original article). 1984--before PDF, WWW, and low-quality scanning to make the PDF. Young(er) geophysicists will be laughing--this seismogram was obtained by the now-lost-art of smoked drum seismographs. The art is to take the drum off the case, wrap it in special white paper, and then hold and rotate it over a smoking kerosene lamp. Since I had to do all of my seismic work in Yellowstone during the winter in 1976 (approximately when this record was obtained), we did all of the smoking in an unheated garage in Yellowstone. Kudos to my colleagues at the time, Rick Hutchinson (now deceased) and Gonzalo Mendoza!

Update on the Attabad landslide

According to the latest report on Dave's Landslide Blog, there is less than 2 meters freeboard before the lake behind the landslide dam reaches the engineered spillway. Monitoring has been difficult because no one is allowed on the dam due to the hazard. I recommend his most recent report in which he addresses the difficulty of predicting exactly when the overtopping will occur, discusses some likely scenarios, and criticizes the shape of the spillway (too narrow, too shallow, and too steep). (Remember that there's not a lot of time for engineering solutions to be implemented--in this case, less than 4 months.)


Before and after photos of the erosion of a landslide dam. Photos from Dave's Landslide Blog, but not sure where he first got them.

He compares the current situation at Attabad with a similar situation that he monitored at Tangjiashan, China, two years ago. (Here's a direct link to his posting on that at a comparable time before breaching. Read forward and backward to see the whole history.) For those who want material for teaching, this is a great example of what the failure of a landslide dam looks like. The dam was formed in 2008 by the Sichuan earthquake. In this case, the spillway was engineered to start eroding when the lake overtopped and started flowing through it. It was not as steep as the Attabad spillway (this is good), but was also too narrow. Five hours after flow started, the dam failed, but the engineering solution had worked fairly well, and Dave is hopeful that the outcome at Attabad will be like this, rather than more catastrophic. Unfortunately, the dam at Attabad is narrower, and so it will be more prone to fail entirely instead of just along the spillway axis. It is also composed of smaller particles than the Tangjiashan dam and will therefore be more erodible.

I have not been able to find out details of evacuations and preparations downstream. Some information is contained on Dave's WWW site in earlier postings.

Live video of Gulf Coast Oil Leak is Available

Photo of the platform Deep Water Horizon by U.S. Coast Guard.


BP has released a streaming video of the source of the oil spill in the Gulf of Mexico. Apparently the position of the camera will be changed sometimes so it should be an interesting video to follow.

Striking aspects of the plume are the unsteadiness of the flow, the existence at times of two streams (a light stream, presumably methane gas, and a darker stream, presumably the oil), the turbulence, and the spiraling rotation of the plume. Prof. Steve Werely at Purdue claimed to the Senate last week that he had used PIV to obtain the discharge rate of oil into the Gulf. PIV tracks individual fluid packets in order to estimate velocities. I do not have access to his velocities, but only to his conclusions. He claims that there are 70,000 barrels per day (3.9 million gallons per day), a value way in excess of the 5,000 barrels per day that BP and the US government have been using. He claims that 25,000 barrels per day are coming out of a 1.2" wide pipe. There are apparently 3 sources of oil, but I've not been able to find the details of the geometry. I did some calculations that show that the velocity would be about 1.5 meters per second. This seems like a reasonable velocity to me from the videos that I've been able to see.

Jupiter Loses a Stripe

On May 9, Australian astronomer Anthony Wesley obtained the photo on the left revealing that the Southern Equatorial Belt (SEB) of Jupiter has faded from view. This is not the first time that the SEB has faded. It fades from view every 3-15 years. Nor was the observation a sudden surprise. In 2009 astronomers had been following the developments, but Jupiter went behind the sun for several months and only re-emerged in March. (Aside: I do not understand why the Great Red Spot is not visible in the right hand image. Am trying to follow up on this.)

The SEB is composed primarily of ammonia ice. One theory is that the belts of Jupiter are lower levels of the atmosphere revealed by gaps in the higher paler clouds. If this is true, then one possibility for the disappearance of the SEB is that it is simply obscured by higher level clouds that have returned to this latitude.

The reappearance of the SEB will occur in perhaps the next year or two, and the event is predicted to be dramatic. Historically it is accompanied by planet-wide outbreaks of violent storms at the latitude of the SEB.

From space.com.

Landslide Dam is about to be overtopped

One of my favorite blogs is "Dave's Landslide Blog". For the past four months he has been regularly tracking the buildup of a large lake behind a dam formed by a landslide that blocked the Hunza River in Northern Pakistan. The lake will be overtopping the dam within a few days (possibly as early as tomorrow).

This landslide, called the Attabad landslide, occurred in early January, killed 14 people, inundated several villages and stranded about 25,000 people. More than 50,000 people could be affected by failure of the dam. As of today, it is estimated that there are only 2-3 meters of freeboard before water starts flowing through the spillway that has been engineered through the dam. A glacial lake outburst flood on May 17 raised the water suddenly by 2 meters. All construction on the spillway has ceased due to the imminent breach. Dave's opinion is that the spillway that has been carved is too small to to accomodate the spring runoff flow of the Hunza River. Seepage through the dam has been ongoing, and one possibility is that the dam will fail because of the seepage. Another possibility is that another landslide will initiate overtopping. A third is that water will flow through the spillway with possible erosion.

Most people in this region are farmers whose only assets are their buildings, their land and their crops. They have been tearing apart their buildings to preserve the construction materials, and are in danger of losing their land and crops. It is a terrible tragedy of which most of the world is unaware.

Volcanic Mesocyclones and Lightning

Mount Pinatubo erupted in 1991. Nearly 20 years later, scientists made careful measurements of the position of the top of the eruption column, the "umbrella", and noted that it rotated (see Chakraborty, P., Gioia, G., and Kieffer, S., Volcanic Mesocyclones, Nature, 458, 497-500, 2010). The rotation induced an instability manifested as waves or lobes on the edge of the umbrella, as shown in the attached figure (from the Nature paper). The image shows a satellite view of the umbrella of Pinatubo. The graph shows rotation rate and growth rate of the umbrella.

The two sketches above show the outline of the edge at different times as documented by satellite photos, and the graphs in the lower left show measured rotation rates. Details are in the Nature paper.

By analogy with meteorologic cyclones, Chakraborty et al. called the eruption plume a "volcanic mesocyclone". Three key elements interact to produce tornadic structures such as dust devils and waterspouts: updraft in the center, downdraughts, and the rotating mesocyclone. Chakraborty et al. proposed that the mesocyclone pulls the ash radially outwards from the core of the updraught, gathering it in an outer sheath where it discharges to produce the spectacular lightning displays that can accompany volcanic eruptions. The color image shows such lightning in the current eruption of Eyjafjallajokull in Iceland. It was taken by Marco Fulle. The other image shows (a) waterspouts spawned during the eruption of Surtsey volcano on November 14, 1963, and (b) the lightning sheath from Mount Chaiten on May 3, 2008.

Contact me at s1kieffer@gmail.com if you would like a PDF of the Nature paper.