Conceptual Image of Sub-seafloor Structure at the JFAST Drilling Site. Credit: (C) JAMSTEC/IODP

Reporting in the journal Science, researchers say they’ve discovered a surprising wrinkle in the geologic story behind one of the most devastating earthquakes in recent memory: the March 2011 Tohoku earthquake that spawned 130-foot tsunami waves, killed 15,800 people and led to a crisis at the Fukushima Daiichi nuclear power plant. The researchers determined that current shear stress on the fault that generated the earthquake is nearly zero. In other words, the violent spasm that released the earthquake also shook out all the pent up stress on the fault.

Alan McStravick, writing in a recent article for the website Red Orbit, explained why this was such a shocker: “The paper’s presentation of this fact flies in the face of the prevailing wisdom that earthquakes will typically only release a portion of the stress on the fault.”

The new results suggest the risk of large earthquakes may be much higher than previously thought, not only in Japan, but near similar megathrust faults around the world.

Working aboard the scientific drilling vessel Chikyu, scientists from the International Ocean Drilling Program (IODP) drilled through the plate boundary fault about 820 meters (0.5 miles) below the seafloor in water nearly 7 kilometers (4.3 miles) deep. They took measurements in the borehole as they drilled, collected core samples and left behind instruments to continue collecting more data over time. (Read the IODP press release about the latest announcement)

Patrick Fulton, a postdoctoral researcher at the University of Texas at Austin’s Institute for Geophysics now at the University of California, Santa Cruz, was a part of the JFAST team and a co-author on the latest study. Fulton blogged about his experiences during the research cruise (read his posts).

A map of the Indian Ocean region shows boundaries of Earth’s tectonic plates in the area, and the epicenters (red stars) of two great earthquakes that happened April 11, 2012. CREDIT: Keith Koper, University of Utah Seismograph Stations.

Three papers in this week’s issue of the journal Nature present startling new findings about an earthquake that struck the Indian Ocean off the coast of Sumatra last April.

As reported by Andrea Mustain at Our Amazing Planet, three features of the quake made it unusual:

First, it was extremely powerful—at magnitude 8.7, it was the sixth most powerful ever recorded. Second, it struck in the middle of a tectonic plate and not along a plate boundary. Third, when the quake zipped along the initial fault and ran into faults intersecting it at right angles, those intersecting faults ruptured too.

Mustain interviewed Thorne Lay, a professor at the University of California, Santa Cruz and co-author of one of the papers:

Lay said that, typically, when earthquakes spread to connecting faults, the rupture rips along faults that branch away from the initial fault like the branches of a river. These earthquakes raced along in a grid-like pattern, making 90-degree turns along faults that resemble a lattice.

“Here, they really do seem to go along perpendicular faults, and we haven’t seen anything like that with a big earthquake,” he said.

So why did this earthquake behave so oddly? Scientists believe they are witnessing the Indo-Australian plate ripping in two, forming a new plate boundary, a process that has already been playing out for millions of years.

Bathymetric map of the Mississippi River near the Bonnet Carre Spillway (BCS). The 90 degree bend upstream of the spillway has no alluvial cover and the channel bed here is consolidated clay. An underwater sand bar covers this clay on the interior bend adjacent to the BCS.

In late spring 2011, one of the largest pulses of water in recorded history traveled down the Mississippi River, threatening the ports, industries, farms and towns of the river’s lower reaches, including New Orleans. To avert disaster, the U.S. Army Corps of Engineers opened the Bonnet Carré Spillway and diverted from 10 to 20 percent of the total river flood discharge into Lake Ponchartrain.

Jeffrey Nittrouer, a National Science Foundation post-doctoral researcher at the University of Illinois, studied the impacts of the diversion shortly after the floodwaters subsided. Surprisingly, he found that 31-46% of the total sand load carried by the river during the 6 weeks the spillway was open was carried through the spillway. The location of the spillway was not intentionally chosen for delta restoration. But Nittrouer determined its land building power came from the fact that it was located on an inside bend of the river downstream from the river-bend apex. This key insight could help scientists and engineers choose the best sites for land-building diversions.

“A tremendous amount of sediment made its way out from this diversion indicating that if the sites of diversions are properly located, there’s the real opportunity to produce much more land than any of us are predicting right now,” says David Mohrig, Nittrouer’s former PhD adviser at the University of Texas at Austin. “It was a very special case in terms of the location, but the net effect of it was they got about as much sand out from the diversion as is estimated to be in the total load of the Mississippi for a whole year.”

This fall, Nittrouer will join the faculty of Rice University.

Read the article “Mitigating land loss in coastal Louisiana by controlled diversion of Mississippi River sand” (Nature Geoscience, July 22, 2012)

Patrick Fulton celebrates successfully drilling through the fault that slipped causing the 2011 Tohoku earthquake

After successfully reentering the wellhead on the edge of the Japan Trench on the seafloor 6926 meters (4.3 miles) below the ship, we began drilling. The goal: to drill ~850 meters (2800 feet) below the seafloor across the plate boundary and through the fault that slipped more than 50 meters (164 feet) at this location during the March 2011 Tohoku earthquake causing the enormous tsunami. We will then try installing a temperature observatory down into the hole to measure the remaining frictional heat across the fault.

Instead of using the standard top-drive drilling system on the ship to rotate the entire drill stem and create the torque on the drill bit 7-8 kilometers below, as in the previous drilling at the site, this time we used a mud-motor located just above the bit to create the torque at the bit. The mud-motor causes rotation of the bit from pumping drilling mud (in our case the mud is actually sea-water) through the motor and out of the jets at the bit.

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Drilling with the mud motor has been incredibly effective and we quickly reached our target depth. We could see from the drilling parameters measured on board that we started to drill through a hard chert we had previously encountered, confirming that we had successfully crossed the plate boundary fault and well into the down-going Pacific Plate.

The great water depth here is much deeper than conventional wells, and the total depth drilled for the observatory joins our other holes as part of the JFAST project in being the deepest below the sea ever drilled for scientific ocean drilling. Our TD (total depth), as shown by the driller’s console in the picture below: 7780.81 meters below the ship’s rig floor!

In the first picture, I’m giving the “thumbs up” for the great depth we were able to obtain. The depth of this deep borehole will provide space for us to install the observatory that will include temperature sensors that straddle the fault zone.

Next, the hole will be cleaned out and all the drill pipe will be returned to the surface. We can then start assembling the observatory and lowering it down to the seafloor for the final, most difficult task of carefully installing it all the way down into the hole.

- Patrick Fulton

Read all the posts in this series:

July 9: Field Update: Return to the Japan Trench
July 13: Field Update: Like Threading a Needle from 7 kilometers away
July 13: Field Update: Drilling Through the Japan Earthquake Fault

The only way we are able to reenter the wellhead on the seafloor, which will allow us to install the observatory into the hole after drilling across the fault, is by finding it with an underwater television camera system (UWTV), slowly moving the 8.5 inch drill bit above the 20 inch opening, and then lowering the pipe down into it.  An added challenge is that the only way to move the drill bit towards and above the well head opening is slowly moving the boat a few meters at a time and then waiting for the 7 kilometer long string of drill pipe to swing beneath us.

Once we were positioned above the GPS location of the wellhead, we slowly lowered pipe down the nearly 7 kilometers below our drilling ship, Chikyu, one 40 meter (130 foot) stand at a time.  We then attached the UWTV around the drill pipe and lowered it down (see photograph) to just above the drill bit. Last May, the stress of raising and lowering the fiber optic cable connecting the UWTV to the ship in such deep water created some damage to the cable, and prevented us from seeing anything or installing the observatory.  Now, at the start of this expedition, the cable was repaired and we attempted using it at depth again for the first time.

It was a long, tense night in the Doghouse (the small enclosure on the rig floor shown in the photograph) trying to find and position ourselves above the wellhead and wondering whether the UWTV would work okay.  Luckily things went well, we found the wellhead with the help of the cameras and a small sonar device on the UWTV, and successfully reentered the hole.

The next critical step is to recover the UWTV, and then drill about 850 meters through the fault zone and into the subducting plate below…

- Patrick Fulton

Read all the posts in this series:

July 9: Field Update: Return to the Japan Trench
July 13: Field Update: Like Threading a Needle from 7 kilometers away
July 13: Field Update: Drilling Through the Japan Earthquake Fault

Greetings from the scientific deep sea drilling vessel Chikyu and the second part of the Japan Trench Fast Drilling Project: JFAST2 – IODP Expedition 343T. The focus of the JFAST project has been to quickly drill into and study the fault that slipped more than 50 meters at shallow depths during the March 2011 M9.0 Tohoku Earthquake and caused the devastating tsunami.

In April and May, we (an international team of ~30 shipboard scientists along with a number of engineers, ship/drilling crew, and onshore support) successfully drilled across the plate boundary fault at ~820 meters (0.5 miles) below the seafloor in water depth nearly 7 kilometers (4.3 miles) deep. This ended up being the deepest below sea level any scientific ocean drilling project has ever gone. We actually did it twice! – the first time we used logging tools to map the geology as we drilled allowing us to pinpoint the fault, we then drilled another hole and collected spectacular core samples through the fault zone. The analysis of the rocks and data are already providing important insight into the mechanics of large earthquakes and tsunamis and will undoubtedly continue to be fruitful for many years to come.

Now I have returned to Chikyu to help undertake the other main goal of the JFAST project, to install a subsurface observatory that will measure the frictional heat signal remaining from the Tohoku earthquake. By measuring the extra heat across the fault at depth we can back out how much frictional resistance the fault had during the earthquake and possibly gain insight into why it slipped more than 50 meters at our study location.

Together with the other JFAST analyses, this unique and important data will not only help us understand the fault and earthquake here, but may also help us understand the potential hazards at other large faults like the Cascadia subduction zone fault off the Pacific Northwest of the United States and British Columbia, Canada.

During the first JFAST expedition, we had many technical problems associated with trying to drill in such deep water for the first time and many delays from weather that prevented us from installing an observatory in the time window we had. We now have been fortunate enough to be given the opportunity to return for one last try.

After flying on board Chikyu by helicopter and transiting North for a couple days, we are now on site and starting to lower pipe down to the seafloor. We plan to then drill across the plate boundary fault once again and then install our observatory of subsurface temperature sensors in the remaining hole. There are many unique challenges with installing such an observatory and with drilling in such deep water depths, but we are all ready and excited to try our best on this difficult mission so we can continue to learn as much as we can from the devastating Tohoku earthquake.

Stay tuned . . . more to come shortly.

- Patrick Fulton

Read all the posts in this series:

July 9: Field Update: Return to the Japan Trench
July 13: Field Update: Like Threading a Needle from 7 kilometers away
July 13: Field Update: Drilling Through the Japan Earthquake Fault

A skull, possibly from a new species of human, recovered from Longlin cave in Guangxi province, China. Photograph: Darren Curnoe

A new study describes human fossils from southern China that have a blending of modern and archaic features. The fossils date from between 11,500 and 14,500 years ago, a time when it was thought that Neanderthals and all other human species had died out except ours (Homo sapiens). Scientists aren’t sure if the new fossils represent a previously undiscovered human species that lived alongside ours, a group of modern humans that migrated from Africa much earlier than other known migrations, or simply modern humans with unusual features.

The report, co-authored by evolutionary biologist Darren Curnoe of the University of New South Wales, appeared online in the journal PLoS One on March 14. The fossilized individuals have been dubbed the Red Deer Cave people after a cave in Yunnan province where several of the fossils were discovered.

According to an article by James Owen for National Geographic News: “The Red Deer Cave dwellers’ unusual features included a flat face, a broad nose, a jutting jaw that lacked a chin, large molar teeth, a rounded braincase with prominent brow ridges, and thick skull bones …”

Still, some scientists claim these features are within the known range of modern human features.

To settle the question of just who these people were, scientists are attempting to extract DNA from the fossils and compare it to modern humans.

Santorini, Greece from LANDSAT. Credit: NASA

Over the past year, Greeks have become accustomed to the feeling of the Earth shifting beneath their feet. Now, it’s not just the economy that’s making them uneasy. Measurements from GPS instruments indicate the ground near the mouth of the island volcano Santorini has deformed by about 2.5 inches since January 2011. In that time, the magma chamber has been growing.

The island is what remains of one of the largest volcanic eruptions in recorded history 3,600 years ago. It destroyed Minoan settlements and may have inspired the legend of the lost city of Atlantis.

According to a post on LiveScience.com by reporter Stephanie Pappas:

If a Santorini eruption did occur, [Andrew] Newman said, it would be nothing like the Minoan eruption of 1650 B.C. that birthed the myth of Atlantis. That eruption was a once-in-100,000-year event, and the expansion of the magma chamber happening now is only 1 percent of what would have gone on prior to the ancient blast.

Russian Team Drills Into Lake Vostok, Antarctica. February 2012

Racing against the oncoming southern winter, Russian scientists announced today they have broken through more than 2 miles of ice to dip into a freshwater lake in eastern Antarctica that had been sealed off from the surface for millions of years. Pressurized water from the lake was allowed to rise up and fill the bore hole before freezing solid.

Next year, the scientists plan to return to sample the lake water. They are especially keen to know if microbes are currently living in one of the most extreme environments on Earth. The lake is seen as an analog for a liquid lake or ocean under the icy crust of Jupiter’s moon Europa.

In a terrific piece on the much anticipated breakthrough for the New York Times today, David Herszenhorn and James Gorman write that environmentalists are concerned about the possibility of contaminating a pristine site with so much scientific potential:

The Russian plan to prevent the drilling fluid from reaching the pristine lake water was to plug the bottom of the bore hole with an inert fluid, Freon, and to drill the final distance with a heated drill tip instead of a motorized drill. Enough kerosene would be removed to lessen the pressure in the bore hole so that when the lake was reached, lake water would flow up the bore hole, then freezing and forming an icy plug. That is exactly what happened, Russian scientists confirmed.

Gifford Miller collects dead plant samples from beneath a Baffin Island ice cap. Miller led a new study which indicates the Little Ice Age began roughly A.D. 1275 and was triggered by repeated, explosive volcanism that cooled the atmosphere. (Credit: Gifford Miller, University of Colorado)

A new study published today in the journal Geophysical Research Letters might settle both questions in one fell swoop. The researchers, led by Gifford Miller, a climate scientist at the University of Colorado, Boulder, say new evidence from northern ice sheets suggests the Little Ice Age was triggered by a series of explosive volcanic eruptions between 1250 and 1300 A.D. The cooling effect from volcanoes is short-lived because aerosols rain out of the atmosphere in just a few years. But, according to Miller and his team, feedbacks with ocean circulation patterns and another set of eruptions 150 years later sustained the cooling.

According to a press release from the American Geophysical Union, which publishes the journal:

During the cool spell, advancing glaciers in mountain valleys in northern Europe destroyed towns. Famous paintings from the period depict people ice-skating on the Thames River in London and canals in the Netherlands, places that were ice-free before and after the Little Ice Age. There is evidence also that the Little Ice Age affected places far from Europe, including South America and China.

To find out how the researchers arrived at their results, read the study, Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks.

Joanna Foster writes in the New York Times Green blog that there’s a warning here about how quickly and durably global climate can be changed:

Bette Otto-Bliesner, a co-author of the study and a climatologist at the National Center for Atmospheric Research, suggested that the study has important implications for the modern-day climate change discussion.

“I think people might look at the Little Ice Age and think that all we need to save us from rising temperatures are some volcanic eruptions or the geo-engineering equivalent,” she said. “But when you see what happened when global temperatures dropped by just one degree and you look at current predictions of six or seven degree increases for the future, you realize how precarious things are for life as we know it.”

“I don’t see a lot of hope that we can somehow compensate for the climate trajectory we’re on,” she said.