HR: 1340h
AN: OS23D-1349    [Abstracts]
TI: Logic-tree Approach for Probabilistic Tsunami Hazard Analysis and its Applications to the Japanese Coasts
AU: * ANNAKA, T
EM: annaka@tepsco.co.jp
AF: Tokyo Electric Power Services Co., Ltd., 3-3, Higashi-ueno 3-chome, Taito-ku, 110-0015 Japan
AU: SATAKE, K
EM: kenji.satake@aist.go.jp
AF: Geological Survey of Japan, AIST, Site 7,1-1-1, Higashi, Tsukuba, 305-8567 Japan
AU: SHUTO, N
EM: shuto@iwate-pu.ac.jp
AF: Iwate Prefectural University, 152-52, Takizawa-aza-sugo, Takizawa, 020-0193 Japan
AU: SAKAKIYAMA, T
EM: sakaki@criepi.denken.or.jp
AF: Central Research Institute of Electric Power Industry, 1646, Abiko, Abiko, 270-1166 Japan
AU: YANAGISAWA, K
EM: yanagisawa.ken@tepco.co.jp
AF: Tokyo Electric Power Co., 1-3, Uchisaiwai-cho 1-chome, Chiyoda-ku, 100-8560 Japan
AB: Probabilistic hazard analysis is commonly used for seismic hazard analysis, but rarely used for tsunami hazard. We propose a logic tree approach to estimate tsunami hazard curves (relationships between tsunami height and probability of exceedance) and present some examples for Japan. The results will be used for quantitative assessments of the tsunami risk for important facilities located on coastal area. The logic tree approach becomes commonly used in probabilistic seismic hazard analysis. Two kinds of uncertainty, aleatory and epistemic, are distinguished. Aleatory uncertainty is due to the random nature of earthquake occurrence and its effects. Epistemic uncertainty is due to incomplete knowledge and data about the earthquake process. A hazard curve is obtained by the integration over the aleatory uncertainties and a large number of hazard curves are obtained by the combinations of the model parameters that represent epistemic uncertainty using the logic tree approach. A probabilistic model for estimating tsunami hazard curves consists of a tsunami source model and a tsunami height estimation model. We developed the logic tree models for local tsunami sources offshore and near the coasts around Japan and for distant tsunami sources along the subduction zone off the west coasts of South America. The logic tree models were made for tsunami source zones, size and frequency of tsunami-generating earthquakes, fault models used in numerical simulation, and standard error of estimated tsunami height. Numerical simulation rather than empirical relation is used for estimating the median tsunami height. Weights of discrete branches that represent alternative hypotheses and interpretations were determined by the questionnaire survey for tsunami and earthquake experts, whereas those that represent the error of estimated value were determined based on the error evaluation. Examples of tsunami hazard curves were illustrated for the coastal sites, and uncertainty in the tsunami hazard was displayed by 5-, 16-, 50-, 84- and 95-percentile and mean hazard curves. This research has been carried out as the project of the Subcommittee on Tsunami Evaluation of JSCE (Japan Society of Civil Enginerrs).
DE: 7223 Seismic hazard assessment and prediction
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting