A giant mass failure in the northern flank of the Kueishantao Island off northeastern Taiwan: debris avalanches and related structures in the offshore downslope
Abstract
Based on the ignimbrite layers, previous studies have shown that Kueishantao volcanic island has probably erupted four times in 7000 years. Strong smell of sulfur can easily detect at east of the island with some plumes from the seabed. In May 2016, an earthquake with magnitude 5 occurred to northeast of the island which has triggered small collapse events in the eastern subaerial part. Recent geophysical surveys have also revealed the distribution of submarine debris avalanches in the north, south and east part off Kueishantao volcanic island. With high-resolution swath bathymetric data, we can observe some debris avalanches distributed with hummocky relief around the island. In this study, we present the marine geophysical data in order to have better understanding of the landslide mechanism from the offshore data of the Kueishantao island, especially with the multi-beam bathymetric data, acoustic backscatter analysis, subbottom profile, sidescan sonar and 3.5kHz echo-sounder. At the north of the island, large-scale debris avalanches extend around 4 km northward with the several blocks height up to more than twenty meters; and, the offshore area of deposit is about 5 km2 of hummocky topography distribution. The scale of debris avalanches may be related to the horseshoe scar of subaerial flank and also submarine flank collapsed events. Nevertheless, to identify the landslide history, we need to analyze the related core data in the future. By analyzing the high-resolution geophysical data, we will discuss the possible mechanism or factors that trigger subaerial flank collapse events and also the transportation of the debris avalanches to the submarine basin. The large-scale collapse events may produce tsunamis and directly affect the coast of northeastern Taiwan.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMOS21A1954H
- Keywords:
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- 4306 Multihazards;
- NATURAL HAZARDSDE: 4313 Extreme events;
- NATURAL HAZARDSDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8110 Continental tectonics: general;
- TECTONOPHYSICS