HR: 0800h
AN: U51A-0017    [Abstracts]
TI: Likely Human Losses in Future Earthquakes in Central Myanmar, Beyond the Northern end of the M9.3 Sumatra Rupture of 2004
AU: Wyss, B M
EM: bmw@benwyss.com
AF: WAPMERR, 1806 N. Izabel Str., Flagstaff, AZ 86004, United States
AU: * Wyss, M
EM: wapmerr@maxwyss.com
AF: WAPMERR, 2 rue de Jargonnant, Geneva, GE 1207, Switzerland
AB: We estimate that the city of Rangoon and adjacent provinces (Rangoon, Rakhine, Ayeryarwady, Bago) represent an earthquake risk similar in severity to that of Istanbul and the Marmara Sea region. After the M9.3 Sumatra earthquake of December 2004 that ruptured to a point north of the Andaman Islands, the likelihood of additional ruptures in the direction of Myanmar and within Myanmar is increased. This assumption is especially plausible since M8.2 and M7.9 earthquakes in September 2007 extended the 2005 ruptures to the south. Given the dense population of the aforementioned provinces, and the fact that historically earthquakes of M7.5 class have occurred there (in 1858, 1895 and three in 1930), it would not be surprising, if similar sized earthquakes would occur in the coming decades. Considering that we predicted the extent of human losses in the M7.6 Kashmir earthquake of October 2005 approximately correctly six month before it occurred, it seems reasonable to attempt to estimate losses in future large to great earthquakes in central Myanmar and along its coast of the Bay of Bengal. We have calculated the expected number of fatalities for two classes of events: (1) M8 ruptures offshore (between the Andaman Islands and the Myanmar coast, and along Myanmar's coast of the Bay of Bengal. (2) M7.5 repeats of the historic earthquakes that occurred in the aforementioned years. These calculations are only order of magnitude estimates because all necessary input parameters are poorly known. The population numbers, the condition of the building stock, the regional attenuation law, the local site amplification and of course the parameters of future earthquakes can only be estimated within wide ranges. For this reason, we give minimum and maximum estimates, both within approximate error limits. We conclude that the M8 earthquakes located offshore are expected to be less harmful than the M7.5 events on land: For M8 events offshore, the minimum number of fatalities is estimated as 700 ± 200 and the maximum is estimated as 13,000 ± 6,000. For repeats of the historic M7.5 or similar earthquakes, the minimum is 4,000 ± 2,000 and the maximum is 63,000 ± 27,000. An exception is a repeat of the M7.5 earthquake of 1895 beneath the capital Rangoon that is estimated to have a population of about 4.7 million. In the case of a repeat of the 1895 event, a minimum of 100,000 and a maximum of 1 106 fatalities would have to be expected. The number of injured can in all cases be assumed to equal about double the number of fatalities. Although it is not very likely that the 1895 event would be repeated in the same location, it is clear that any medium to large earthquake in the vicinity of Rangoon (at a distance similar to the M7.2 earthquake of May 1930) could cause a major disaster with more than 10,000 fatalities. In spite of the uncertainties in these estimates, it is clear that the capital of Myanmar, and the provinces surrounding it, will likely experience major earthquake disasters in the future and the probability that these could occur during the next decades is increased. We conclude that major efforts of mitigation, using earthquake engineering techniques, and preparation for seismological early-warning capabilities should be undertaken in and near Rangoon, as well as in other cities with more than 100,000 inhabitants (e.g., Phatein, Bago and Henzada).
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Union [U]
MN: 2007 Fall Meeting