Mr. Leonardo Seeber
Earth Institute Contact: Mr. Leonardo Seeber
The whole world, not just the science community, was caught unprepared by the events that unfolded in the northern Indian Ocean on December 26, 2004. The global societal and political fall-out from the giant earthquake (Mw 9.0) and tsunami might take decades to settle. On February 14 th 2005, Japan's Marine Science and Technology Center (JAMSTEC) will send the R/V NATSUSHIMA to the forearc off northern Sumatra where the tsunamigenic earthquake occurred. JAMSTEC has invited LDEO to send a scientist to participate in the two legs of the R/V NATSUSHIMA and to become involved in the subsequent analysis of the data to be acquired. This provides us a great opportunity to discover the structural changes in the forearc wrought by the great earthquake and aftershocks while the evidence is still fresh. It is an opportunity the US marine and solid earth science community should not pass up. Because time is short and our interest in participating in these cruise legs with the Japanese is very high, we are requesting a Small Grant for Exploratory Research (SGER) to cover the cost of sending scientists to participate in the two legs, and to fund a small portion of the subsequent post-cruise data analysis. The proposed work falls under the “quickresponse research on natural disasters and similar unanticipated events” purpose of SGER awards.
The two legs of the R/V NATSUSHIMA expeditions to the epicentral area will involve high resolution bathymetric mapping using the Seabat8160 sonar, the short-term and long-term deployment of several OBSs, and direct observation and sampling with the ROV HYPER DOLPHIN. The lead PI will participate in the expedition of the R/V Natsushima this month. Back at LDEO, the PIs will analyze the Japanese OBS data using the double difference hyper-accurate locating technique, coupled with determinations of focal mechanisms from first-motion of waveform data. They will also reprocess the multibeam bathymetric data for highlighting the surficial traces of the plate boundaries and the seafloor signature of the December 26 2004 event. This work will be carried out in close collaboration with Japanese colleagues.
Results from this survey will provide better delineation of the structural fabric across the plate boundary zone offshore Sumatra. While the subduction trench is well located, various evidence suggest that strike-slip faults are active within the forearc basins. By learning the effects of this devastating earthquake on the seafloor, we will better be able to recognize the signature of earlier such events. In this way, we might be able to map the spatial extent of prior events, and to evaluate their mean recurrence interval, such information being critical for a meaningful evaluation of seismic risk.
While we will be writing scientific papers eventually, our first mission is to share the results as quickly as possible with the public for future disaster preparedness and mitigation. There will be media on board and if we find fresh fault traces, that information will be broadcast immediately, along with any other interesting findings. This survey will embark scientists from various international institutions. It will thus provide us with the opportunity to strengthen relations with Japanese, German and Indonesian colleagues, all of whom have been investigating this area for the past decade.
Cross Cutting Themes:
Hazards and Risk