The South China Sea region, which covers the South China Sea and its adjoining basins including Sulu Sea and Celebes Sea, is identified as one of the most vulnerable regions to major tsunamigenic earthquakes due to the high seismicity of the Manila Trench, Cotabato and Negros Trench and Sulawesi Trench. According to historical records, a number of devastating tsunamis have occurred in the region. For example, the tsunami which hit Keelung in 1867 is believed to have resulted in the loss of several hundred lives. More recently, the tsunami generated by the M8.1 earthquake which hit Moro Gulf of the Celebes Sea in 1976 resulted in over 8,000 dead or missing, 10,000 injured and 90,000 homeless. The recent Mw 7.0 earthquake in 2006 off Taiwan once again raised attention and awareness of tsunami hazard of the region. To tackle tsunami risk in the region, the international community has launched a coordinated plan of action. The Twenty-third Session of the Intergovernmental Coordination Group for the Pacific Tsunami Warning and Mitigation System (ICG/PTWS-23, 16-18 February 2009, Samoa) formed a Working Group on Tsunami Warning and Mitigation System in the region to, among other functions, promote and facilitate tsunami hazard and risk studies in the region. There are already a significant number of studies on the tectonic, seismicity, historical earthquakes, tsunami records as well as tsunami risk assessments of the South China Sea region with results published in peer-reviewed journals. The results of those studies will form a good basis for further tsunami hazard and risk assessment in the region. The historical tsunami events discussed above had mainly local impacts and there is very little historical information on events affecting a large region of the South China Sea. Some of the big questions are: • Is the Manila Trench the only structure capable of producing a South China Sea wide tsunami? • What is a comprehensive list of possible tsunami sources in the South China Sea region (local, regional, distant)? • Are any sources outside the region a potential hazard for the South China Sea region? • How large an earthquake can be produced by the Manila Trench and other potential sources as listed by the group? • What is the return period for Manila Trench and other main source events? In view of the large volume of knowledge in the studies discussed above, and the diversity of some of the study results, the IOC proposes holding a three-days scientific meeting of relevant experts to review historical records, discuss the most likely sources and probability of occurrence of earthquakes and tsunamis for coordinated scenario analysis of future events and hazard mitigation schemes for the South China Sea region. The expected outcome of the workshop will be a better understanding of the tsunami hazard and risk in the South China Sea region which can feed into the planning for the establishment of the sub-regional Tsunami advisory centre, as well as allow Member States to better understand their level of tsunami exposure. The proposed major topics for discussion at the workshop are: 1. Paleoseismology and historic events in the South China Sea region and Philippines Trench 2. Seismic studies and potential tsunamigenic sources in the South China Sea region 3. Technical/Scientific development of tsunami modelling for the South China Sea region, including key parameters