報告書番号

U98017

タイトル（和文）

1998年パプア・ニューギニア地震津波現地調査報告

タイトル（英文）

Characteristics and Damage Investigation of the 1998 Papua New Guinea Earthquake Tsunami

概要 （図表や脚注は「報告書全文」に掲載しております）

1998年7月17日現地時間18時49分頃、パプア・ニューギニア北西部近海で地震が発生、津波が沿岸に来襲し、死者・行方不明者をあわせると2,000名を越える大災害となった。筆者は文部省の災害調査団に加わり、現地調査を行なった。その結果、以下のことがわかった。(1)犠牲者の大多数は津波によるものと考えられる。集落によっては人口の75%を失ったところもある。(2) 海岸は陸に向かって低地の続く直線の砂浜海岸であるが、津波による最大水位は、最高で約15m、海岸に沿って約40kmにわたり5mを越えている。(3)地震の規模(Mw 7.1)と比較して、津波による最大水位が異常に大きい。なお、地震の特徴から1992年ニカラグア地震津波等のようなスローアースクェークの可能性は低く、断層運動とは別の現象が地震を契機として生じ、津波が増幅された可能性が強い。現状では、大規模な地滑りが発生したという考えが有力である。

概要 （英文）

On 17 July, 1998, an earthquake with moment magnitude Mw 7.1(estimated by Harvard Univ.) occurred at 18:49(local time) on the north west part of Papua New Guinea. Several minutes after the main shock, huge tsunami attacked the north coast of Sissano and Malol, where the coast is composed of straight beach with white sand, and about 7,000 people had lived in high floor wooden houses. Due to the tsunami, more than 2,000 people were killed. To investigate damage by the tsunami, a survey team of seven members was organized in Japan. The author took part in the survey team, which was headed by Prof. Kawata of Kyoto University. We stayed in the Papua New Guinea from 30th July through 10th August 1998 to investigate the maximum water level, to interview the people about the phenomena caused by the earthquake and the tsunami, and to set three seismographs.These results imply that: (1) By main shock, an earthquake intensity of ６ on the Richter scale was felt in Sissano and Malol. In the coast area near Sissano and Malol, liquefaction took place. (2) More than 2,000 people were killed mainly due to the tsunami. (3) The maximum water level of the tsunami was about 15m. (4) It seems that the tsunami caused not only by crustal movemen, but also by other factors. This is suggested by the fact that the measured maximum water level was beyond 10 times larger than the estimated one, which was calculated by numerical simulation based on known fault parameters.It is highly probable that a submarine landslide was one of main factors which amplified the tsunami.

報告者

キーワード