Tag Archives: seismology

Seismology could soon be used to protect elephants from poachers

An innovative approach could help monitor elephants using earthquakes, and even protect them from poachers.

This image shows an African elephant with a visualization of the vibrations it generates, which can be used to determine its behavior. Image credits: Robbie Labanowski.

A story of elephants and earthquakes

As undergrads, we used to analyze open data from some seismographs in the city. Some were old and picked up a lot of noise and, on one of them, there was a strange wave that appeared every 10 minutes or so. It was too regular to be earthquake-related and, as it turns out, it was the local subway. Just like earthquakes, other things can generate waves that can be picked up by seismological equipment — in this case, it’s elephants.

In a new study, researchers describe how seismology could be used to track the movement of elephants, as well as their vocalizations.

The results seem to back the theory that elephants use ground vibrations for long-distance communications, but it’s surprising to see just how strong these vibrations really are.

“We were surprised by the size of the forces acting on the ground that were generated by elephants when they vocalize,” says Beth Mortimer of the Universities of Oxford and Bristol, UK. “We found that the forces generated through elephant calls were comparable to the forces generated by a fast elephant walk. This means that elephant calls can travel significant distances through the ground and, in favorable conditions, further than the distance that calls travel through the air.”

Mortimer focuses on animals that use vibrations to communicate between themselves — previously, she studied spiders and their webs but now, she’s moved to a bigger target. She believes that conservationists could ultimately design an alarm system using elephant-generated vibrations as a trigger.

Along with Will Rees, a Masters student, she recorded vibrations generated by wild elephants in Kenya while they displayed different behaviors, including walking and calling. They wanted to see how far elephant-generated vibrations travel and how they are affected by the terrain type and human noise.

They found that, under ideal conditions, the vibrations can be picked up from several kilometers away, but this varies greatly on the type of terrain and existing noise. A surprising result they gathered was that human noise can actually be very disruptive for the elephant calls — in other words, humans interfere with the elephants’ ability to communicate with each other over great distances.

But when the seismological receivers were close enough, they could be used to not only detect elephants, but also monitor their behavior and assess when they are threatened by poachers.

“We suggest that monitoring ground-based vibrations can be used in a practical context to not only detect elephants, but determine their behaviors,” Mortimer says. “Using multiple seismic recorders in remote locations, we suggest that detection, location, and classification algorithms can be generated that allow monitoring of elephants in real-time.”

However, before this can be realistically achieved, much more experimental data needs to be gathered and refined. Geophysicist Tarje Nissen-Meyer at the University of Oxford, UK, who was also involved in the study, wants to set up a larger, long-term network of seismic sensors. Along with aerial, visual, and acoustic surface sensors, a seismic network might also offer valuable information and alert park rangers when elephants are in trouble.

“We hope to build on these initial findings to develop a comprehensive approach for monitoring and understanding the behavior of large mammals in these pristine, changing, and fragile environments,” Nissen-Meyer says.

The study “Classifying elephant behaviour through seismic vibrations”, by Mortimer et al., has been published in Current Biology:  https://www.cell.com/current-biology/fulltext/S0960-9822(18)30420-2

Project drills deep in New Zealand to understand and predict earthquakes

For the first time, geophysicist in New Zealand will place seismic sensors deep into a geological fault to record the build-up and occurrence of massive earthquakes, potentially giving crucial  information about one of the biggest faults in the world.

It’s hard to say anything after such an insightful and well explained video. The Alpine Fault runs for about 600 kilometres along the west coast of South Island, marking the boundary between the Pacific and Australian tectonic plates. It is a planar discontinuity over a huge volume of rock, across which there has been significant displacement – see the mountains.

Every year, the two tectonic plates slide by each other by about 2.5 centimeters; it may not seem like much, but just think of the incredibly massive volumes which are sliding this way, creating friction and building up pressure – and just think what the effects will be over hundreds of years. Geologists are confident that the fault is “ready to break in its next earthquake” — with a 28% chance of a rupture in the coming 50 years, which is another reason why this project is so important.

“If we go on to record the next earthquake, then our experiment will be very, very special,” says Rupert Sutherland, a tectonic geologist at New Zealand’s Institute of Geological and Nuclear Sciences in Lower Hutt, and one of the project’s leaders. “A complete record of events leading up to and during a large earthquake could provide a basis for earthquake forecasting in other geological faults.”

The costs of the project are $2 million, which are not that high when you consider the potential implications. The first step is to collect geological samples, then dig a shallow borehole and insert sensors into it. The hole will then be deepened and strengthened, and after this, more seismic sensors will be added. This will hopefully be done by December. Then, the data will be directly analyzed and inserted into computer models of faults, in order to better understand when and how faults break, and how this is foreshadowed.

For example, one idea is that large differences in groundwater pressures on either side of the fault zone could indicate that a big quake is imminent.

“The fault appears to currently form an impermeable barrier, and it’s likely that time-dependent differences in groundwater pressure on either side of the fault play a role in governing earthquake nucleation processes and the radiation of seismic waves,” says John Townend, a seismologist at Victoria University of Wellington, who is part of the project.

seismometer ancient

World’s first earthquake detector was invented 2000 years ago in China

seismometer ancient

A modern replica of Zhang Heng’s famous seismoscope. Photo: Houfeng Didong

A seismometer or seismoscope is an instrument that detects and measures the motions of the ground as a result of seismic waves gushing from an earthquake, volcanic eruption or powerful explosion. Today, there are thousands of such instruments dispersed in key places around the world that constantly keep watch, gather data and help seismologists better their understanding of how earthquakes work. And no, we can’t predict earthquakes yet.

You might be surprised to find, however, that the first seismometer was invented in China in 132 AD by a Chinese astronomer, mathematician, engineer, and inventor called Zhang Heng.

The instrument was said to resemble a wine jar six feet in diameter, with eight dragons positioned face down along the outside of the barrel, marking the primary compass directions. In each dragon’s mouth was a small bronze ball. Beneath the dragons sat eight bronze toads, with their broad mouths gaping to receive the balls.

When the instrument sensed an incoming seismic wave, one of the balls would drop and the sound would alert observers to the earthquake, giving a rough indication of the earthquake’s direction of origin.

The device is said to have been very accurate and could detect earthquakes from afar, and did not rely on shaking or movement in the location where the instrument was positioned.

The first ever earthquake recorded by this seismograph was supposedly somewhere in the east. Days later, a rider from there reported this earthquake. Moreover, it had the most wicked ornaments. They don’t make scientific instruments like they used to!

Illustration of world's first seismoscope.

Illustration of world’s first seismoscope.

Of course, the insides of the seismometer was filled with a sensing mechanism of some sort, the contents of which have been lost in time. In all likelihood, a simple or inverted pendulum was employed, according to experts.

In 2005, scientists in Zengzhou, China built a replica of Zhang’s seismoscope, estimating the content of the inner mechanism by using technology that was available during the great inventor’s time. They used the replica to detect simulated earthquakes based on waves from four different real-life earthquakes in China and Vietnam. The seismoscope detected all of them. As a matter of fact, the data gathered from the tests corresponded accurately with that collected by modern-day seismometers!

 

 

Mobile US seismic array maps American mantle

A laudable, ambitious initiative is nearing fruition: the US$90-million Transportable Array, a moveable grid of seismometers that blankets America.

Since 2004, the set of 400 seismometers, loaded on trucks, have gradually marched, from the Pacific coast across the Rocky Mountains and the Great Plains and is finally reaching the eastern coastline. Whenever they arrive at the specified location, scientists dig holes and bury instruments in plastic cases. The project’s purpose is to establishe the best picture yet of the mantle beneath the North American continent.

earthscope2

Source: IRIS.

Reaching a few hundred kilometers beneath the surface, the array analyzes how natural waves from earthquakes move in the mantle and the crust, painting the most accurate picture so far. The array works similar to a CT scan – moving across the surface and gathering information from more and more points.

“As the array has moved, the whole picture of what’s under North America has gotten much sharper,” says Andy Frassetto, a seismologist at the Incorporated Research Institutions for Seismology (IRIS) in Washington DC, which operates the stations.

Having almost finished their work in 48 states, they are now heading over to Alaska, where the toughest challenge awaits. The Transportable Array, along with other permanent and temporary seismic stations, is one of three cornerstones making up the larger EarthScope initiative. EarthScope is an earth science program using geological and geophysical techniques to explore the structure and evolution of the North American continent and to understand the processes controlling earthquakes and volcanoes. The EarthScope initiative has three components – the seismometers are just the first one. The second one is a set of GPS that measure tiny movements in the Earth’s crust, and the third one is a 3.2-kilometre-deep hole drilled into California’s San Andreas fault – but this step experienced a big setback when instruments lowered down the hole stopped working after just days for an unknown reason. But the first two initiatives more than made up for that:

“We’ve learned a lot more by integrating things together than we would have by doing them separately,” says Robert Smith, a geophysicist at the University of Utah in Salt Lake City, and an early leader of EarthScope.

Source: IRIS.

Source: IRIS.

Researchers are now eagerly waiting for the equipment to arrive in Alaska, which will provide some of the most valuable data from all the country. Alaska’s geology is interesting to say the least, with the the Pacific crustal plate slamming into and diving under the continent. But even with this spectacular tectonic development, little has be done to improve our understanding of the area – in part because the state is so big and it costs a lot to probe all of it, and partially because of the rough conditions.

“We have sort of a ‘zeroth’ order of understanding,” says Rick Saltus, a USGS geophysicist in Denver. Now, he says,“we’ll get the first order”.

(c) Brown University

Ancient tectonic plate re-discovered beneath California

(c) Brown University

(c) Brown University

Millions of years ago, an ancient tectonic plate called the Farallon oceanic plate used to sit between the Pacific and North American plates. In time, the plate “disappeared” beneath the North American one, however geologists at Brown University have now found physical surface remnants of the plate under sections of central California and Mexico. The Farallon surface fragments may now explain a seismic anomaly in the region that has eluded scientists for some time.

Though they used to be spaced apart by the Farallon plate, currently the North American and Pacific tectonic plates are joined through a continental transform fault known as the San Andreas fault. In the process the Farallon plate was forced underneath the North American one through subduction, leaving a few small remnants at the surface that became part of the Pacific plate.

Research carried out by Brown University geologists has revealed however that bits of the Farallon plate have remained attached at the surface. Surprisingly part of Mexico’s Baja region as well as a considerable landmass in central California rest upon slabs of this ancient plate.

Oddly enough, close to the region a seismic anomaly has been registered in the Sierra Nevada mountains in the Golden State. Dubbed the  Isabella anomaly, it suggests that a sizable mass of relatively cool and dehydrated material is present at a depth of 100 to kilometers below the Earth’s surface. This was found after many years ago geologists mapped out the region many miles beneath the earth’s surface by transforming seismic waves that can be fast or slow into actual images. These seismic waves travel at velocities varying according to the materials they encounter.

For some time, geologists have been trying to explain this peculiarity and many theories have been proposed to justify it, like delamination – the breaking of  the lithospheric plate under the mountains. High-magnesium andesite deposits on the surface near the eastern edge of the anomaly found by the Brown researchers, often linked to the melting of the oceanic crust, provided evidence, however, that in fact the Farallon plate broke off and melted into the mantle.

This evidence convinced Brown geophysicist Donald Forsyth and his collaborators that the Isabella anomaly might also be part of a slab connected to an unsubducted fragment of the Farallon plate. The findings, published in the journal Proceedings of the National Academy of Sciences, might warrant a new investigation into the ancient plate tectonics of western North America, especially considering the region is extremely seismically active.

“The geometry was the kicker,” Forsyth said. “The way they line up just makes sense.”

“However the Sierra Nevada was delaminated,” Forsyth said, “it’s probably not in the way that many people had been thinking.”

Tsunami strikes Solomon islands following big earthquake

A massive earthquake struck Wednesday east of Kira Kira in the Solomon Islands, with several already confirmed victims and injuries.

tsunami solomon

“At 12 minutes past midday, a 7.9 earthquake in the Santa Cruz Islands (near the Solomon Islands) occurred. A shallow event.” He said. “The nearest part from our location estimate is an island called Ndeni, which is part of the Santa Cruz Islands. They would have had quite strong shaking and could potentially have some damage there from shaking.”

For other areas there is no big tsunami alert, though waves somewhere between 90 cm’s and 1.5 meters have remained localized around the coast of the Solomon Islands. A flood alert has also been issued.

Professor James Goff, Director of the Tsunami and Natural Hazards Research Group at the University of New South Wales feared the worst when the magnitude 8.0 quake struck at the Santa Cruz Islands, part of the South Pacific nation of Solomon Islands on Wednesday from a depth of 5.8 kilometers.

“The Mag 8.0 Santa Cruz earthquake was originally reported by the United States Geological Survey to be about 5.8 km deep which made me think “oh no, here we go again, this will be a bad one”, but subsequent bulletins from the Pacific Tsunami Warning Center placed it at 33 km deep which at the very least reduces the likelihood of the tsunami being too bad.”

Solomon-islands-quake-001tsuna

The size of both the earthquake and the tsunami took seismologists somewhat by surprise.

“In reality we know very little about the long-term earthquake and tsunami activity of the entire Solomon Islands region and so cannot say with any confidence whether this type of event we have seen today is out of the ordinary or how often we might expect it to happen in the future. Much work needs to be done to improve our understanding of such events in the Solomon Islands for the safety of both local and regional communities.”, he said.

New earthquake models show ‘stable zones’ not so stable after all

A recent study conducted by Californian and Japanese seismologists claims that stable fault areas might not be so stable, in terms of earthquake generation. The controversial findings suggest that creeping fault behavior (more on this in the next paragraph) is actually not only instable, but also capable of creating fast slipping earthquake ruptures.

Faulty issues

fault

Faults are planar rock fractures, where the two sides move relatively one to another. Most earthquakes happen on tectonic plate boundaries, but those that don’t, typically happen on faults. When an earthquake happens, the two sides of a fault move fast, but not all the segments of the fault move the same; the general belief is that there are some (relatively) stable segments, who act as barriers against massive earthquake ruptures – these are the segments that exhibit creeping behaviour. However, this new study claims otherwise.

“What we have found, based on laboratory data about rock behavior, is that such supposedly stable segments can behave differently when an earthquake rupture penetrates into them. Instead of arresting the rupture as expected, they can actually join in and hence make earthquakes much larger than anticipated,” says Nadia Lapusta, professor of mechanical engineering and geophysics at Caltech and coauthor of the study, published January 9 in the journal Nature.

Lapusta worked with Hiroyuki Noda, a scientist at JAMSTEC (Japan Agency for Marine-Earth Science and Technology) and former postdoc at CalTech, analyzing both stresses acting on the fault and friction and the resistance of the slip – but the method they used was rather unique.

“The uniqueness of our approach is that we aim to reproduce the entire range of observed fault behaviors—earthquake nucleation, dynamic rupture, postseismic slip, interseismic deformation, patterns of large earthquakes—within the same physical model; other approaches typically focus only on some of these phenomena,” says Lapusta.

fault 3

UMERICAL SIMULATIONS ILLUSTRATE THAT FAULT SEGMENTS CAN MOVE SLOWLY AND STABLY OVER LONG PERIODS OF TIME AND LATER HOST LARGE EARTHQUAKES. DASHED LINES REPRESENT SLOW SLIP EVERY 50 YEARS ALONG A CROSS-SECTION OF THE FAULT, WITH THE NUMBERS INDICATING THE SIMULATED TIME IN YEARS. EARTHQUAKES ARE SHOWN BY SOLID LINES PLOTTED EVERY SECOND. THE AREA MARKED PATCH B CAN BOTH SLIP SLOWLY (E.G., DASHED LINES ABOVE THE 4,500 YEAR MARK) AND PARTICIPATE IN LARGE EARTHQUAKES (E.G., YELLOW EVENT). (Credits:CalTech)

In addition to creating the model, the team also assigned realistic fault properties to the model faults – using data obtained from laboratory modelling.

“In that experimental work, rock materials from boreholes cutting through two different parts of the fault were studied, and their properties were found to be conceptually different,” says Lapusta. “One of them had so-called velocity-weakening friction properties, characteristic of earthquake-producing fault segments, and the other one had velocity-strengthening friction, the kind that tends to produce stable creeping behavior under tectonic loading. However, these ‘stable’ samples were found to be much more susceptible to dynamic weakening during rapid earthquake-type motions, due to shear heating.”

The results seemed pretty conclusive, raising even more concern on fault earthquakes, including extreme events – like the one which is expected to occur on the San Andreas fault, in L.A, and places which appear relatively earthquake-free.

“Creeping fault segments can turn from stable to destructive due to dynamic weakening” appears in the January 9 issue of the journal Nature.

Via Nature and JAMSTEC

Gulf Stream diagram

Huge methane deposits trapped in seabed sediments might get released due to warmer waters

Gulf Stream diagram

Gulf Stream flow diagram.

Scientists have found hints that methane deposits, tucked away in seabed sediments, have began to breakdown from their frozen state. The shifting of the Gulf Stream from colder to warmer waters is to blame, the researchers note. While a significant greenhouse gas influx into the atmosphere might occur, the researchers conclude, based on their models and experimental data, that it would take thousands of years for the methane to sublimate into gas.

“We know methane hydrates exist here and, if warming continues, it can potentially lead to less stable sediments in this region,” says Matthew Hornbach, a marine geologist at the Southern Methodist University in Dallas, Texas, who led the study.

The study suggests some 2.5 gigatonnes of methane hydrate along the continental slope of the eastern United States are currently subjected to destabilizing. Temperature alone isn’t enough to cause their release, however underwater land slides can trigger such an event, and the region is particularly prone to them.

While it’s yet unclear what impact such a quantity of methane released in the atmosphere might have on global warming, one thing certain is that such an event is far from happening in the near future. The scientists used seismic data collected in 1977 to model where they expected the frozen methane to become gaseous in the western North Atlantic margin. After correcting interference in their model to better reflect reality, the scientists found that water was much cooler in the area before.

After modeling heat flow through the methane hydrate sediments in relation to time at the current temperature, the authors found that it would take some 5,000 years for all the methane to sublimate and become gas.  “We don’t know where we are in the 5,000-year time frame, but our best approximation suggests we are 800 to 1,000 years in,” says Phrampus.

While the study offers relief by presenting the slim chances of such an event occurring in the near future, it does highlight the potential danger that the destabilization of greenhouse gas deposits poses. There are many hydrate deposits around the world that deserve attention, like the ones located in the Arctic seabed. The region’s waters have warmed significantly in the past decades, and since it’s the place undergoing the maximum amount of change, it’s therefore the best place to study these dynamics. Also, whether destabilized hydrates can make the continental slopes more unstable is a discussion still far from reaching a widely approved conclusion.

“The embarrassing reality is we don’t have any solid confirmation that these connections are causative rather than correlative,” says Charles Paull, a marine geologist at Monterey Bay Aquarium Research Institute in Moss Landing, California, who has studied this western Atlantic region in detail.

Findings were reported in the journal Nature.

Massive Indian Ocean quakes may signal tectonic break-up

The past few years have been marked by numerous seismic events, some of dramatic magnitude; aside from the huge 9.1 temblor in Japan, the world was also shocked by the pair of massive earthquakes that rocked the Indian Ocean on 11 April 2012. However, as geophysicists warn, this may only be the beginning – the birth of a new plate boundary.

A pair of massive earthquakes

Credits: Harvard University

The undersea earthquakes measured magnitudes of 8.6 and 8.2 and triggered tsunamis throughout the Indian Ocean. The damage was somewhat smaller than what you’d expect, but now, researchers claim their effects may be more far-reaching than first believed. Basically, the earthquakes were caused by accumulated geologic stress breaking the Indo-Australian plate apart; when they took place, they released energy across numerous faults and unleashed aftershocks for almost a week afterwards.

Ever since the 1980s, researchers believed the Indo-Australian plate is breaking apart, but until now, there hasn’t really been any conclusive evidence to support those claims. The April 11 earthquakes represents the most spectacular example of the process in action, as Matthias Delescluse, a geophysicist at the Ecole Normale Supérieure in Paris explains: “it’s the clearest example of newly formed plate boundaries,” he says.

Plate tectonics

According to generally accepted theories, the internal stressing and deformation of the Indo-Australian plate began some 10 million years ago; while the plate moved northwards, the Indian part was stopped by the Eurasian plate and dove under the Himalayas, rising them. However, the Australian part forged ahead, creating the tension which is breaking the plate apart today.

Gregory Beroza, a seismologist at Stanford University in Palo Alto, California, is also a believer in this model:

“The 2004 and 2005 earthquakes by themselves would not have caused this other earthquake. There had to be other stresses”, he says.

Earthquakes and strike-slips

Most earthquakes form at the boundary of tectonic plates, as you can see from the second picture above; one plate drifts beneath the other, creating massive earthquakes – this is called subduction. However, this is not the only form of contact between plates: plates or portions of plates can also slip by each other, horizontally, resulting in what is called as ‘strike-slip’ earthquakes. Typically, these earthquakes are smaller and less dangerous (though dangerous as well).

However, the first of the two earthquakes defied all expectations, being the largest strike slip earthquake on record, and one of the biggest to occur away from any plate boundaries.

Another study drew some pretty interesting, but worrying conclusion: the earthquake was created by accumulated stress throughout the plate, and the release of this stress created one of the most complex fault patterns in the world – something you really don’t want to hear if you live in that area. Typically, an earthquake like this shakes along a single fault, or maybe two if it’s a really big one; but this one shook no less than four faults, one of which slipped more than 20 meters. While this pattern has been described partially in previous work, nobody has analyzed slip amounts in so much detail: Beroza says that Lay and his team “do a splendid job of picking apart this very important earthquake” in their paper.

Aftershocks

So not only was this earthquake unique due to its high magnitude and slip, its aftershocks are also special. In yet another study, researchers found that for the six days following the temblor, aftershocks with magnitudes bigger than 5.5 occurred 5 times more often than normal.

“Aftershocks are usually restricted to the immediate vicinity of a main shock,” says lead author Fred Pollitz, a geophysicist at the US Geological Survey in Menlo Park, California.

However, this changes the general belief of how soon and how close aftershocks can occur after earthquakes, raising the importance of this particular earthquake even more.

“Every earthquake is important to study, but this earthquake is rather unique,” says Hiroo Kanamori, a seismologist at the California Institute of Technology in Pasadena.

Scientific sources: 1 2 3

New twist in Italian seismologists trial

I will take the risk of being quite subjective: the trial against the Italian seismologists just got a lot more absurd. Six seismologists and one government official are charged with manslaughter after telling the public there is no major risk of an earthquake, right before the deadly temblor in 2009. Yesterday, the much anticipated and feared hearing took place, and a Californian expert took the stand, heavily criticizing the Italian experts.

The trial begins

All those indicted took part in a meeting held in L’Aquila on 30 March 2009, during which they were asked to assess the risk of a significant earthquake in the area, in view of the many shocks that had occurred recently. After the meeting, Bernardo De Bernardinis, deputy head of the Department of Civil Protection, declared:

“The scientific community tells me there is no danger because there is an ongoing discharge of energy,” a statement that most seismologists consider to be scientifically incorrect.

Just a week after that, a 6.3 earthquake struck L’Aquila, killed 309 people, and De Bernarnidis, as well as the experts who advised him, were charged with manslaughter. Now, seismology is a frontier science; we cannot, at the moment, predict earthquake nor fully understand the information we extract from earthquakes. We can speak in terms of probability and energy, and more often than not, there is no clear line between right and wrong. Arguably, the Italian team made a mistake – you could even say it was a big mistake. But if you ask me, it is totally unfair to trial somebody for being scientifically wrong in seismology, particularly in the light of new developments in the case:

Guido Bertolaso, who was at the time De Bernardinis’s direct superior was revealed to have set up the meeting to convey a reassuring message, regardless of the scientists’ opinion, and he also turned out to be the direct source of the ‘energy discharge’ statement. This changed his status from key witness to defendant, and tried to defend himself. He explained that the meeting was a ‘media move’, not with the purpose of underestimating the risks, but rather putting some order in the chaotic reports storming from the media. He was especially referring to Giampaolo Giuliani — a laboratory technician and amateur seismologist who was alarming the population, warning of a big earthquake to come.

The thing is, in some situations, smaller tremors (like the ones in Italy) can release energy and thus eliminate the risk of a ‘big one’, but in other cases they are only a warning of worse things to come. Bertolaso claimed he heard the first possibility from the Italian National Institute for Geophysics and Volcanology (INGV) and he used it publicly, without being corrected by any seismology experts. Enzo Boschi, former INGV president and one of the defendants has denied this, but he has yet to take the stand and explain himself.

Experts against experts

Things took a turn for the worse when Lalliana Mualchin, former chief seismologist for the Department of Transportation in California, came in to testify as an expert for the prosecution. He is one of the few seismologists in the world to openly criticize the Italian team, and refused to sign the letter supporting the indicted seismologists signed by about 5,000 international scientists. Mualchin claims the seismic hazards weren’t properly estimated in L’Aquila:

“Italy is one of the countries with the best seismic knowledge in the world. And yet look at what a 6.3 earthquake has done to this city. That knowledge was not used, and scientists are responsible for that. They were conscious of the high risk in the area, and yet did not advise the people to take any precaution whatsoever”, he said.

The problem is indeed a scientific one, and a tough one to crack as well. The Italian scientists relied on a method called the probabilistic seismic-hazard analysis (PSHA), a method that analyzes the frequency of the earthquakes in an area to estimate probabilities of future temblors. The method is used in many countries and is considered by most to be state of the art, but in Mualchin’s view, this method systematically underestimates seismic hazards because it doesn’t take into consideration very rare and extreme events.

“Frequency is not important, what really matters is the largest earthquake we can expect, the strongest one that has happened in the past. Risk prevention should be based on that,” he said.

This is the philosophy behind deterministic seismic-hazard analysis, a method which Mualchin claims has wrongfully been abandoned by the scientific community, up to the point where younger seismologists haven’t heard about it. Having worked in seismology myself, I can confirm this – I’ve only rarely come across this method, and when I have, it was rather mentioned than explained.

“PSHA is a bad model California has exported elsewhere, and we see the results here in L’Aquila,” he told Nature after the hearing. Mualchin worries that the new building codes approved in Italy after the L’Aquila earthquake show no improvement. “They never consider the worst-case scenario for any particular area, and this can lead to new disasters in the future”.

The case continues, and Mualhin may be right. The US might have wrongfully exported this model instead of a better one, and the Italians may have made a big scientific mistake. But when working on the frontier of human knowledge, being charged for manslaughter for being wrong is just unacceptable; there is no clear method, no obvious direct way for estimating earthquake likeliness, and as much as the Italians want to point the finger at someone and find people to blame, in my humble opinion, they should just accept the fact that this is where we are, scientifically, at the moment.

Via Nature

Dinosaur extinction ocean of lava

New dinosaur extinction theory: an ocean of lava

Dinosaur extinction ocean of lava

It wasn’t just a devastating asteroid that killed off all the dinosaurs 65 million years ago. Scientists from Boston University now claim that a massive eruption of lava fronts around the world, coinciding with the asteroid impact, sealed their fate forever.

The controversial theory is betting on two unusually hot blobs of mantle 1,700 miles beneath the crust that formed just after Earth itself, 4.5 billion years ago. These mantle stores are responsible for huge amounts of lava gush from the bowels of the Earth, flooding more than 100,000 square kilometres, leaving behind distinct geological regions known as large igneous provinces (LIPs).

Matthew Jackson at Boston University and his team found 62-million-year-old basalts from the North Atlantic LIP contain isotopes of elements in ratios that reflect the chemistry of early Earth’s mantle. The scientists claim that this is hard evidence supporting the supposed fact that LIPs are fed by the 4.5-billion-year-old stores of mantle.

“There is an amazing correlation between mass extinctions and LIPs,” Andrew Kerr at the University of Cardiff says.

These ancient magma stores might actually be still active to this day. Using seismic waves to probe the mantle’s structure, scientists found two unusual areas some 2800 kilometres down, beneath Africa and the Pacific Ocean.

It’s an interesting idea – that a giant blob of hot magma might burp from near Earth’s core every now and then, causing havoc for life,” says Gerta Keller at Princeton University, but adds more work is needed to support the hypothesis.

The researchers themselves also admit that they can perfectly understand why this theory can be considered highly controversial, however they believe it’s still highly plausible.

 

Aerial image of Cleveland Volcano. (c) Alaska Volcano Observatory

Alaskan volcano shows signs of eruption

Aerial image of Cleveland Volcano. (c) Alaska Volcano Observatory

Aerial image of Cleveland Volcano. (c) Alaska Volcano Observatory

Increased heat emissions by a volcano located in the Aleutian were detected via satellite by the Alaska Volcano Observatory, which has issued an eruption advisory alert. Recent activity has increased the volcano to a Yellow Alert.

Mt. Cleveland, 5,676 ft. AGL, also referred to as Cleveland volcano is emitting seismic activity that seems to correlate with the heat emission reports. These measurements indicate the volcano could erupt at any moment, spewing ash clouds up to 20,000 feet (3.7 miles/6 km) above sea level with little further warning, the observatory said.
Located on a deserted island, 45 miles west of Nikolski and about 150 miles west of Unalaska/Dutch Harbor, in case of an eruption Cleveland is too far off any major settlements to cause any damage. A great incovenience might lay, however, with the International Trans-Pacific flights using the great circle route make flights daily over this portion of the Aleutian Islands. So far, airlines have not changed their flight patterns because of Cleveland’s heat emissions, said Steve McNutt, a University of Alaska Fairbanks scientist who works at the observatory.
The last time Clevaland erupted was in 2001, when it blasted ash more than 5 miles (8 km) into the sky and spilled lava from the summit crater. Cleveland has experienced several smaller eruptions or suspected eruptions since then.
Volcanoes are pretty unpredictable, and although scientists know from current measurements that its at risk of eruption, they can’t tell without a real-time seismic network at Cleveland, AVO when its going to eventually pop-out exactly. It could happen tomorrow, or just as well ten years from now.
“Short-lived explosions with ash clouds that could exceed 20,000 ft. above sea level can occur without warning and may go undetected on satellite imagery for hours. Low-level ash emissions at Cleveland occur frequently and do not necessarily mean a larger eruption is imminent.  AVO continues to monitor the volcano using satellite imagery,” website source explain.

Massive earthquake hits Japan… again

The seismological events near Japan are far from reaching an equilibrium; a 7.4 or 7.5 earthquake on the Richter scale struck apan’s Miyagi Prefecture and its vicinity in northeastern Japan at 23:32 p.m. (1432 GMT) local Time Thursday, the Japan Meteorological Agency (JMA) said.

The area is not so far away from the major 9.0, which hints at related seismic activity, but more thorough research is conducted in order to find out more about this; the tsunami alert that was originally issued was retreated, and nuclear power plants are under no additional threat.

At the crippled and troubled Fukushima power plant, radiation levels remain high, but there hasn’t been an additional elevation caused by this recent earthquake. It’s still uncertain if this kind of earthquakes will continue to appear in the near future, but it’s definitely something worth considering.

Despite the fact that it hasn’t caused significant damage, blackouts have been reported throughout the whole region, and people are agitated and wondering when the situation will calm down. It’s still unclear if this was an isolated event or part of the “legacy” left by the big temblor, but as the days pass questions are going to be answered. All in all, it’s great to see that there wasn’t any serious damage done, and people are handling this extremely well.