More than 40 percent of minors in Lorca suffer post-traumatic stress a year after earthquake

A mask, painted by a U.S. Marine who attended art therapy to relieve posttraumatic stress disorder symptoms

Spanish researchers have analysed the impact of the Lorca catastrophe by the percentage of minors suffering post-traumatic stress. Results reveal that 55% of young people displayed this disorder a month on from the earthquake and 40% were still suffering a year later.

On 11 May 2011, Lorca suffered an earthquake measuring 5.1, preceded by another of 4.5, which killed nine people and caused significant material damage.

Two experts from the University of Murcia compared the prevalence of post-traumatic stress disorder (PTSD) on the population of minors in the region in its acute phase (one month after the quake) and as a chronic condition (one year later).

"The analysis indicates that 55% of the minors suffered from post-traumatic stress one month after the earthquake, while after one year this had decreased to 40%," as Concepción López Soler, researcher from the University of Murcia and co-author of the study with Juan José López García, explained.
The results, published in the journal Gaceta Sanitaria, reveal that 75% of the minors presented re-experiencing symptoms (recurrent thoughts, nightmares and physiological manifestations) after one month and 60% after one year.

In addition, a month later, 42% suffered from avoidance of anything related to the tragedy (memory disturbances, emotional blockage) and 24% after one year. 51% also displayed hyperarousal (sleeping difficulties, irritability and concentration problems) after a month and 38% a year later.

The authors argue that post-traumatic reactions generally tend to disappear over time. "After the earthquake new mental health resources were implemented to assist people with severe post-traumatic stress," stresses López Soler.

Primary school pupils in their 3rd and 6th year in educational centres from the municipal area were asked for their voluntary participation in this study. One month after the earthquake the level of PTSD was assessed in 495 minors and in 374 after one year.

"It is important to highlight that the younger age groups and girls are more sensitive to developing these symptoms, which coincides with the results of other studies," the Murcian researcher points out. "Young girls in particular are a special risk group."

Among the younger students, 54% of girls showed symptoms of post-traumatic stress compared to 39% of boys.

The evaluation was carried out using the Diagnostic and Statistical Manual of Mental Disorders criteria (DSM-IV-TR), using the Child PTSD Symptom Scale (CPSS) questionnaire which was developed to evaluate the post-traumatic stress in minors after an earthquake in Northridge (Los Angeles, USA) in 1994.

Stress after trauma
"Natural disasters create a sense of loss of personal safety and endangered survival among the population," adds López Soler. Earthquakes are one of the disasters which cause the greatest psychological disturbances in the population and PTSD is the reaction most associated with adverse conditions.

"With previous earthquakes, the affected population has been quite variable," she states. Three years after the Turkey earthquake in 1999, the prevalence of PTSD was 59%; 18 months after the earthquake in Kashmir (between India and Pakistan), it was 64.8% and ten months after the disaster in L'Aquila (Italy) in 2009, it was greater than 60%.

In comparison with other studies, the prevalence of PTSD is somewhat lower, which according to the authors can be understood to be due both to the lesser intensity of the earthquake and its consequences, and swift normalisation of the environment.

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Source: Plataforma SINC

Summary: Spanish researchers have analyzed the impact of the Lorca catastrophe by the percentage of minors suffering post-traumatic stress. Results reveal that 55% of young people displayed this disorder a month on from the earthquake and 40% were still suffering a year later. On 11 May 2011, Lorca suffered an earthquake measuring 5.1, preceded by another of 4.5, which killed nine people and caused significant material damage.

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The Vancouver: Nearby Georgia basin may amplify ground shaking from next quake

Multiple scenarios for earthquakes within the Georgia Basin underneath Vancouver indicate that earthquakes would be amplified. Credit: Sheri Molnar and Kim Olsen

Tall buildings, bridges and other long-period structures in Greater Vancouver may experience greater shaking from large (M 6.8 +) earthquakes than previously thought due to the amplification of surface waves passing through the Georgia basin, according to two studies published by the Bulletin of the Seismological Society of America (BSSA). The basin will have the greatest impact on ground motion passing over it from earthquakes generated south and southwest of Vancouver.

"For very stiff soils, current building codes don't include amplification of ground motion," said lead author Sheri Molnar, a researcher at the University of British Columbia. "While the building codes say there should not be any increase or decrease in ground motion, our results show that there could be an average amplification of up to a factor of three or four in Greater Vancouver."

The research provides the first detailed studies of 3D earthquake ground motion for a sedimentary basin in Canada. Since no large crustal earthquakes have occurred in the area since the installation of a local seismic network, these studies offer refined predictions of ground motion from large crustal earthquakes likely to occur.

Southwestern British Columbia is situated above the seismically active Cascadia subduction zone. A complex tectonic region, earthquakes occur in three zones: the thrust fault interface between the Juan de Fuca plate, which is sliding beneath the North America plate; within the over-riding North America plate; and within the subducting Juan de Fuca plate.

Molnar and her colleagues investigate the effect the three dimensional (3D) deep basin beneath Greater Vancouver has on the earthquake-generated waves that pass through it. The Georgia basin is one in a series of basins spanning form California to southern Alaska along the Pacific margin of the North America and is relatively wide and shallow. The basin is filled with sedimentary layers of silts, sands and glacial deposits.

While previous research suggested how approximately 100 meters of material near the surface would affect ground shaking, no studies had looked at the effect of the 3D basin structure on long period seismic waves.

To fill in that gap in knowledge, Molnar and colleagues performed numerical modeling of wave propagation, using various scenarios for both shallow quakes (5 km in depth) within the North America plate and deep quakes (40 -- 55 km in depth) within the Juan de Fuca subducting plate, the latter being the most common type of earthquake. The authors did not focus on earthquakes generated by a megathrust rupture of the Cascadia subduction zone, a scenario studied previously by co-author Kim Olsen of San Diego State University.

For these two studies, the authors modeled 10 scenario earthquakes for the subducting plate and 8 shallow crustal earthquakes within the North America plate, assuming rupture sites based on known seismicity. The computational analyses suggest the basin distorts the seismic radiation pattern -- how the energy moves through the basin -- and produces a larger area of higher ground motions. Steep basin edges excite the seismic waves, amplifying the ground motion.

The largest surface waves generated across Greater Vancouver are associated with earthquakes located approximately 80 km or more, south-southwest of the city, suggest the authors.

"The results were an eye opener," said Molnar. "Because of the 3D basin structure, there's greater hazard since it will amplify ground shaking. Now we have a grasp of how much the basin increases ground shaking for the most likely future large earthquakes."

In Greater Vancouver, there are more than 700 12-story and taller commercial and residential buildings, and large structures -- high-rise buildings, bridges and pipelines -- that are more affected by long period seismic waves, or long wavelength shaking. "That's where these results have impact," said Molnar.

Source: Seismological Society of America

Summary: Tall buildings, bridges and other long-period structures in Greater Vancouver may experience greater shaking from large earthquakes than previously thought due to the amplification of surface waves passing through the Georgia basin, according to two new studies. The basin will have the greatest impact on ground motion passing over it from earthquakes generated south and southwest of Vancouver.

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The Building 'belt' offers cheap, quick repair of earthquake damage

A damaged building joint repaired with post tensioned metal straps and tested on a shaking table to the equivalent level of a magnitude 7 earthquake. Credit: University of Sheffield

Four years after the January 2010 earthquake, 145,000 people still remain homeless in Haiti. A cheap and simple technology to repair earthquake damaged buildings -- developed at the University of Sheffield -- could help to reduce these delays by quickly making buildings safe and habitable.

Recent tests showed that a damaged building repaired using the technique could withstand a major earthquake -- similar in scale and proximity to the buildings that collapsed during the Haiti earthquake.
The technology involves wrapping metal straps around each floor of the building, which are then tensioned either by hand or using compressed air tools. It is designed for use on reinforced concrete frame buildings -- a common construction technique around the world, including countries like Haiti. Unlike other repair methods, it does not require expensive materials or a high level of technical knowledge, making it ideal for use in the developing world.

Lead researcher, Professor Kypros Pilakoutas, explains: "The strapping works very much like a weight-lifter's belt, by keeping everything tightly compressed to reduce tension on the concrete columns of the structure.

Concrete works well under compression, but not when pulled under tension and this is why it has to be reinforced for use in construction. When the reinforcement is faulty or damaged, it can be very expensive to repair.

"Our method not only makes the building stable again very quickly, but it increases the building's ability to deform without breaking, making it more able to withstand further earthquake movement."
The team tested the technique on a full scale, two-storey building, built according to an old European standard which has inadequate reinforcing to withstand earthquakes. This construction is typical of many buildings in the developing world, as well as many Mediterranean buildings built before the 1980s.

The building was constructed on a specially designed 'shaking table' which can simulate ground movement caused by earthquakes. During the first test, the building was very near collapse following a small earthquake similar in scale to a magnitude 4 on the Richter scale having about 10000 times less energy than the Haiti earthquake.

The building was then repaired using the post-tensioned metal straps and retested. The researchers were unable to make the building fail during a major earthquake similar in scale to the magnitude 7 Haiti earthquake at the epicentre and stopped the test at that point.

Professor Pilakoutas hopes the new technology will not only speed up the response to major earthquakes, but could also prevent the damage happening in the first place. The cost of the materials for a typical small building column is about £20 and it would take a crew of two people around 2 hours to complete the strengthening. For a typical small dwelling having 6 columns, the seismic rehabilitation would cost around £200 and could be completed in a few days, rather than cost several thousand pounds and take months with other traditional rehabilitation techniques such as jacketing with steel plates or concrete.

"Ideally, governments shouldn't wait until a disaster happens, but should be identifying buildings at risk and taking steps to make them strong enough to withstand any future earthquakes," he says. "Because this method causes minimal disruption and is cheap to apply, it's ideal for bringing existing buildings up to standard -- both in the developing world and in earthquake risk areas in Europe as well."


Source: University of Sheffield

Summary: Four years after the January 2010 earthquake, 145,000 people still remain homeless in Haiti. A cheap and simple technology to repair earthquake damaged buildings could help to reduce these delays by quickly making buildings safe and habitable.

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Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion.

This artist’s impression depicts the magma chamber of a supervolcano with partially molten magma at the top. The pressure from the buoyancy is sufficient to initiate cracks in the Earth’s crust in which the magma can penetrate. Credit: ESRF/Nigel Hawtin

Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger. The results are published in Nature Geosciences.

The team was led by Wim Malfait and Carmen Sanchez-Valle of ETH Zurich (Switzerland) and comprised scientists from the Paul Scherrer Institute in Villigen (Switzerland), Okayama University (Japan), the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon (France) and the European Synchrotron (ESRF) in Grenoble (France).

A well-known supervolcano eruption occurred 600,000 years ago in Wyoming in the United States, creating a huge crater called a caldera, in the centre of what today is Yellowstone National Park. When the volcano exploded, it ejected more than 1000 km3 of ash and lava into the atmosphere, 100 times more than Mt Pinatubo in the Philippines did in 1992. Big volcanic eruptions have a major impact on the global climate. The Mt Pinatubo eruption decreased the global temperature by 0.4 degrees Celsius for a few months. The predictions for a super volcano are a fall in temperatures by 10 degrees Celsius for 10 years.

According to a 2005 report by the Geological Society of London, "Even science fiction cannot produce a credible mechanism for averting a super-eruption. We can, however, work to better understand the mechanisms involved in super-eruptions, with the goal of being able to predict them ahead of time and provide a warning for society. Preparedness is the key to mitigation of the disastrous effects of a super-eruption."

The mechanisms that trigger supervolcano eruptions have remained elusive to date. The main reason is that the processes inside a supervolcano are different from those in conventional volcanoes like Mt. Pinatubo which are better understood. A supervolcano possesses a much larger magma chamber and it is always located in an area where the heat flow from the interior of Earth to the surface is very high. As a consequence, the magma chamber is very large and hot but also plastic: its shape changes as a function of the pressure when it gradually fills with hot magma. This plasticity allows the pressure to dissipate more efficiently than in a normal volcano whose magma chamber is more rigid. Supervolcanoes therefore do not erupt very often.

So what changes in the lead up to an eruption? Wim Malfait explains: "The driving force is an additional pressure which is caused by the different densities of solid rock and liquid magma. It is comparable to a football filled with air under water, which is forced upwards by the denser water around it." Whether this additional pressure alone could eventually become sufficiently high to crack Earth's crust, leading to a violent eruption, or whether an external energy source like an Earthquake is required has only now been answered.

Whilst it is virtually impossible to drill a hole into the magma chamber of a supervolcano given the depth at which these chambers are buried, one can simulate these extreme conditions in the laboratory. "The synchrotron X-rays at the ESRF can then be used to probe the state -- liquid or solid -- and the change in density when magma crystallises into rock" says Mohamed Mezouar, scientist at the ESRF and member of the team. Jean-Philippe Perrillat from the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon adds: "Temperatures of up to 1700 degrees and pressures of up to 36,000 atmospheres can be reached inside the so-called Paris-Edinburgh press, where speck-sized rock samples are placed between the tips of two tungsten carbide anvils and then heated with a resistive furnace. This special set-up was used to accurately determine the density of the liquid magma over a wide range of pressures and temperatures."

Magma often includes water, which as vapour adds additional pressure. The scientists also determined magma densities as a function of water content.

The results of their measurements showed that the pressure resulting from the differences in density between solid and liquid magma rock is sufficient in itself to crack more than ten kilometres of Earth's crust above the magma chamber. Carmen Sanchez-Valle concludes: "Our research has shown that the pressure is actually large enough for Earth's crust to break. The magma penetrating into the cracks will eventually reach Earth's surface, even in the absence of water or carbon dioxide bubbles in the magma. As it rises to the surface, the magma will expand violently, which is the well known origin of a volcanic explosion."


Source: CNRS

Summary: Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger.

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