Edison Gica

Numerical simulation of the 1992 Flores tsunami: Interpretation of tsunami phenomena in northeastern Flores Island and damage at Babi Island

Numerical analysis of the 1992 Flores Island, Indonesia earthquake tsunami is carried out with the composite fault model consisting of two different slip values. Computed results show good agreement with the measured runup heights in the northeastern part of Flores Island, except for those in the southern shore of Hading Bay and at Riangkroko. The landslides in the southern part of Hading Bay could generate local tsunamis of more than 10 m. The circular-arc slip model proposed in this study for wave generation due to landslides shows better results than the subsidence model, It is, however, difficult to reproduce the tsunami runup height of 26.2 m at Riangkroko, which was extraordinarily high compared to other places. The wave propagation process on a sea bottom with a steep slope, as well as landslides, may be the cause of the amplification of tsunami at Riangkroko. The simulation model demonstrates that the reflected wave along the northeastern shore of Flores Island, accompanying a high hydraulic pressure, could be the main cause of severe damage in the southern coast of Babi Island.

Field survey of the 1994 Mindoro Island,Philippines Tsunami

This is a report of the field survey of the November 15, 1994 Mindoro Island, Philippines, tsunami generated by an earthquake (M = 7.0) with a strike-slip motion. We will report runup heights from 54 locations on Luzon, Mindoro and other smaller islands in the Cape Verde passage between Mindoro and Luzon. Most of the damage was concentrated along the northern coast of Mindoro. Runup height distribution ranged 3–4 m at the most severely damaged areas and 2–4 in neighboring areas. The tsunami-affected area was limited to within 10 km of the epicenter. The largest recorded runup value of 7.3 m was measured on the southwestern coast of Baco Island while a runup of 6.1 m was detected on its northern coastline. The earthquake and tsunami killed 62 people, injured 248 and destroyed 800 houses. As observed in other recent tsunami disasters, most of the casualties were children. Nearly all eyewitnesses interviewed described the first wave as a leading-depression wave. Eyewitnesses reported that the main direction of tsunami propagation was SW in Subaang Bay, SE in Wawa and Calapan, NE on Baco Island and N on Verde Island, suggesting that the tsunami source area was in the southern Pass of Verde Island and that the wave propagated rapidly in all directions. The fault plane extended offshore to the N of Mindoro Island, with its rupture originating S of Verde Island and propagating almost directly south to the inland of Mindoro, thereby accounting for the relatively limited damage area observed on the N of Mindoro.

LONG-TERM EFFECTS OF SOCIAL RESPONSES IN THE 1994 MINDORO TSUNAMI DISASTER IN ORIENTAL MINDORO, PHILIPPINES

本研究は，被災後の居住規制により移住を余儀なくされた被災者の生活再建や地域社会の復興状況、および、それらを支援する中央・地方政府などの活動の長期的効果の把握を目的として実施した1994年フィリピン・ミンドロ地震津波災害による被害を受けた集落への現地調査の結果をまとめたものである．その結果，「Food-for-Work」と呼ばれる住宅再建手法などが効果的に作用し，政府による移住地開発は一定の成功を収めていることが分かった．ただし，さらに今後の動向には，土地所有者証明書の早期の発行や家庭をも巻き込んだ防災教育の継続が重要であることも分かった．