more earthquaking news...or clarifications =)
Apparently, the news item below is making the rounds via e-mail. The item was obviously culled from a recently concluded study called Earthquake Impact Reduction Study for Metropolitan Manila (MMEIRS) sponsored by JICA, with PHIVOLCS & MMDA comprising the project steering committee. Following are clarifications, which I hope would put the news item in proper perspective. The Magnitude 7.2 earthquake is not a prediction over a specified time; rather it is the estimated largest credible earthquake that can be generated by movement of the Valley Fault System (VFS, a.k.a. Marikina Fault) -- which runs right through Metro Manila -- based on available geological & seismological data. That is, IF the VFS moves, a M7.2 earthquake CAN be generated. This could produce ground shaking up to Intensity VIII or IX (measured using the 10-step PHIVOLCS Earthquake Intensity Scale) in Metro Manila. MMEIRS did consider other possible sources of earthquake (Philippine Fault, Lubang Fault, Manila Trench, etc.), and found the VFS the biggest threat to Metro Manila. The above estimate of earthquake hazard is very reasonable. However, the study does not quantify the likelihood of such an event. MMEIRS used a deterministic method in assessing the hazard -- i.e., we determined the VFS as a worst-case source of earthquake, and estimated the probable maximum earthquake this fault can generate. This method is different from a probabilistic approach, where one estimates the likelihood of an event over a specified time, say, 50 years. So, geologically speaking (over an UNSPECIFIED time), the VFS moving -- thus generating an earthquake up to M7.2 -- is inevitable. We knew this even before MMEIRS. We do not know, however, WHEN this will happen. Earthquake prediction is still an elusive quest anywhere in the world. For an appreciation of the risk, suffice to say that historically, the Metro Manila area has indeed been repeatedly affected by disastrous earthquakes. What we therefore recommend is to systematically prepare for such an eventuality. MMEIRS focuses on the effects of a big earthquake in Metro Manila and how best to prepare for such an event. The estimates of damage & casualties are based on empirical observations worldwide, considering population, number of buildings, construction practices, etc. They are very rough estimates, but they do indicate what we've expected all along: damage & casualty CAN be very high, especially considering that the metropolis is host to 14 million people. So the study makes recommendations at various levels of government (national, regional, local), as well as at community level where NGOs & POs can play a big role. Community-based disaster management exercises were conducted in pilot areas during the course of the study. The recommendations I believe are the more important output of MMEIRS. Some background information on MMEIRS are in www.mmeirs.org. For more information, please visit our office or our website www.phivolcs.dost.gov.ph. MMEIRS is a landmark study. But it's just a start. Copies of the study's final report have been given to members of the MMEIRS Technical Working Group (TWG), which include LGUs, the National Disaster Coordinating Council, selected national government agencies, utility companies and the like. It is important to note that the TWG members have in fact contributed to the contents of the study. We recognize that much of the burden of preparing for and mitigating natural hazards lies with LGUs, although an earthquake striking Metro Manila is inevitably a national calamity. Sad to admit, but awareness of earthquake risks is new to many Filipinos. And preparedness is alien to our culture. Bahala na, ika nga ng marami. This is often reflected in our urban development plans (or lack thereof). On the bright side, some LGUs have enthusiastically welcomed the study. Hopefully the MMEIRS report could guide them in the right direction. Hope this helps to clarify the news item. Although we promote disaster risk awareness and preparedness, we do not wish to cause unnecessary panic or despair among the people, so please help us in prudently distributing this email. Disaster risk mitigation efforts should be deliberate, systematic, coordinated & continuous. Sincerely, Norman M. Tungol Chief, Geology & Geophysics Research & Development Division Philippine Institute of Volcanology & Seismology PHIVOLCS Bldg., C.P. Garcia Ave. U.P. campus, Diliman 1101 Quezon City Tel. +63(2)426-1468 to 1479 Fax. +63(2)920-7058 ------------------------ Yahoo! Groups Sponsor --------------------~--> Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar. Now with Pop-Up Blocker. 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