Deepest ever scientific ocean drilling could hold key to understanding earthquakes (10/2/2007)

CHIKYU sailing in Tokyo Bay

One of the most ambitious earth science expeditions yet mounted to gain a better understanding of the earthquake process, has begun off the coast of Japan.

Dr Lisa McNeill, of the University of Southampton's School of Ocean & Earth Science, based at the National Oceanography Centre, Southampton, and Joanne Tudge, of the Department of Geology, University of Leicester, are taking part in the multi-disciplinary study of a 'subduction' zone off the Japanese coast, aboard the deep-sea drilling vessel Chikyu (which means 'Planet Earth' in Japanese). This is the maiden scientific voyage of this vessel, which has unique capabilities enabling it to access new regions of the Earth's crust.

Large-scale subduction earthquakes are the world's most powerful seismic events and the cause of major catastrophes, such as the 2004 Boxing Day earthquake and tsunami in the Indian Ocean.

Japan, which has endured devastating earthquakes in cities such as Kobe in 1995, has made major investments in technology, including Chikyu, to learn more about seismic activity near its shores.

Lisa, a lecturer at Southampton, joins the Nankai Trough Seismogenic Zone Experiment (or NanTroSEIZE) expedition, part of the Integrated Ocean Drilling Program (IODP), as a scientific participant, but will also serve as a co-chief scientist on a later phase of the experiment in 2009.

PhD student Joanne Tudge is part of the Geophysics and Borehole Research Group in the Department of Geology at Leicester, which has a long-standing history of providing logging services and expertise for the IODP. Her research focuses on interpreting data from the borehole to better understand the sediments. On this NanTroSEIZE expedition she will be working to classify the rocks and understand the physical properties of the sediments in the subduction zone.

The project is ambitious in scale - the first phase alone is the longest period of scientific ocean drilling ever attempted in one area. In the second phase, colleagues will attempt to break the scientific ocean-drilling depth record by targeting a fault around 3500 m below the sea floor.

During the third phase, the drill ship aims to reach the main plate boundary at 6 km and place long-term monitoring tools. The experiment will take samples and install observatories to assess, for example, how strain is building up on the fault, the effects of fluid on rocks and the physical properties of sediments as they are deformed.

Dr McNeill said, "The scale of this experiment is unprecedented and I am very excited to be taking part. This is an extremely challenging expedition but the results should give us a much greater understanding of the processes responsible for generating earthquakes and tsunami."

The ship sailed from Japan on 21 September and the experiment can be followed on the JAMSTEC website.

Note: This story has been adapted from a news release issued by the Natural Environment Research Council

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