Research press release


Nature Geoscience

Geoscience: Origin of destructive earthquakes and tsunamis in the Banda Sea, Indonesia

インドネシアの、破壊的な地震と津波が歴史的に発生した原因は、最近発見された、海底の伸長断層系にあることする報告がNature Geoscience に掲載される。伸長断層系では、断層帯に沿って沈む堆積物が津波を引き起こす。今回の知見は、この極めてテクトニクス的に活動的な地域における地震と津波災害に新たな理論をもたらす。


今回、Phil Cumminsたちは、既存の地質学的情報と地殻変動のGPS観測およびこの地域における歴史地震と津波の解析を、特に1852年の事象に焦点を合わせて組み合わせた。彼らは、バンダ諸島に破滅的被害を与えた1852年バンダ地震と他の4つの歴史的な地震は、沈み込みに関連した深部の震源ではなく、浅い傾きを持つ伸長断層系が引き金となったことを見いだした。さらに、著者たちは、津波は地震自体が直接的に引き金となったのではなく、地震により不安定になった断層帯に沿った海洋堆積物の崩落が引き金となったことを突き止めた。


Devastating historical earthquakes and tsunamis in Indonesia can be traced to a recently discovered submarine extensional fault system, where sediment slumping along the fault zone triggers the tsunamis, according to a study published in Nature Geoscience. These findings provide a new theory for earthquake and tsunami hazard in this highly tectonically active region.

A number of destructive events in the Banda Sea have been documented from the seventeenth century onwards, including detailed reports of the large 1852 Banda earthquake and tsunami in Indonesia. This event, along with the others, had been assumed to have been caused by compressional faults in the subduction zone - where one tectonic plate plunges below another - that underlies the Banda Sea. However, there is geological evidence of submarine extensional faulting that suggests this region has recently been experiencing stretching rather than compression.

Phil Cummins and colleagues combined existing geological information with GPS observations of crustal motion and an analysis of historical earthquakes and tsunamis in the region, with a particular focus on the 1852 event. They found that the 1852 Banda earthquake and four other historical earthquakes that devastated the Banda Islands were triggered by the shallowly dipping extensional fault system, rather than a deeper source related to subduction. Furthermore, the authors found that slumping of marine sediment destabilized by the earthquakes along the fault zone triggered the tsunamis, rather than the tsunamis being directly triggered by the earthquakes themselves.

The authors conclude that their findings demonstrate that earthquake-induced sediment slumping can trigger large tsunamis, and that - in the Banda Sea - seismic activity in a region of extensional tectonics is a source of large earthquake and tsunami hazard for Indonesia.

doi: 10.1038/s41561-020-0545-x

「Nature 関連誌注目のハイライト」は、ネイチャー広報部門が報道関係者向けに作成したリリースを翻訳したものです。より正確かつ詳細な情報が必要な場合には、必ず原著論文をご覧ください。

メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週最新のNature 関連誌のハイライトを皆様にお届けいたします。