Funding to study earthquake region (5/18/2008)

A major research consortium has just started to investigate the causes of devastating earthquakes in south-east Asia.

The research team, led by the National Oceanography Centre, Southampton (NOCS), are surveying the region struck by the 2004 and 2005 Sumatran earthquakes and tsunami to determine how the structure of major faults affects the size of large earthquakes.

The team has been awarded more than £2m by the Natural Environment Research Council (NERC) to carry out the research, which will combine data recorded during the earthquakes with new observations of the seafloor and sub-seafloor plate boundary zone.

The project will provide critical information about what happened during the Sumatran earthquakes, and whether similar events might have happened in the past. This will have important implications for understanding the risk from future earthquakes both in Sumatra and elsewhere.

All plate boundaries are divided into segments - sections of fault that are distinct and behave differently from one another. Barriers between these segments often limit how far a particular earthquake ruptures. But it is not known what determines whether an earthquake ruptures only a single segment, staying relatively small, or jumps across the barriers between segments to become a major event.

"The Sumatran earthquakes provide a unique framework to tackle this problem", explains Dr Tim Henstock, a NOCS geophysicist at the University of Southampton and Principal Investigator for the project. "The southern boundary of the major 2004 earthquake - the southernmost point at which the fault slipped - stopped the rupture, and therefore limited the earthquake magnitude, but we don't yet know why this boundary is there, nor how it controls the earthquake rupture process."

The project aims to understand this behaviour, and was designed to combine observations of the earthquakes with measurements of the faults beneath the seafloor, linking the dynamics of the rupture to the static structure of the plate boundary. The study will collect many different geophysical and geological datasets around the earthquake rupture barriers exploring different properties at many different scales. The data will improve understanding of the shape of the two tectonic plates and the properties of the sediments and fluids within them, all of which influence how an earthquake propagates along a fault.

A complementary experiment on land installed instruments on Sumatra and the islands overlying the plate boundary zone in April 2008. They will record waves from earthquakes all over the world to image deep into the subduction system and will show which faults are currently most active.

The 130-day shipboard programme started this week, using the German R/V Sonne. Dr Mike Webb from NERC said, "This is the largest exchange of marine facilities that we have ever undertaken. As well as providing an excellent platform for this important study, we hope the project will demonstrate the expanding cooperation between European research fleets. Because the Sonne is already working in the area, this exchange is logical and more efficient."

Note: This story has been adapted from a news release issued by NERC

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