GSNZ Wellington branch meeting
P-Cable 3D seismic imaging of the 1888 Ritter Island sector collapse in the Bismarck Sea
presented by Christian Berndt, GEOMAR, RSNZ Julius von Haast Fellowship
Volcanic sector collapses are the most tsunamigenic geological processes apart from subduction zone earthquakes. The collapse of Ritter Island in 1888 constitutes one of the few sector collapses that occurred in historical times and that was observed by eyewitnesses. This provides a unique opportunity to calibrate tsunami models. In 2016, we conducted a six week-long expedition with R/V Sonne to image the sector collapse deposits to obtain information on the slide geometry and constrain tsunami models. The sector collapse evacuated most of the slide scarp and incised deeply into the seafloor between the islands of Umbar and Sakar before spilling out into the Bismarck Sea abyssal plain. High-resolution 3D seismic reflection data document that the sector collapse was the culmination of a few thousand years of slow slope deformation and that parts of the flank moved several hundred metres seaward before being buttressed by another volcanic edifice. The ensuing tsunami simulations showed that the tsunami was mainly controlled by the movement of the upper part of the volcanic edifice. Both the slower and deeper deformation of the flank and the explosive eruption did not contribute significantly to the observed tsunami. P-Cable technology was essential for imaging the interior of the volcano and the study would not have been possible with different seismic methods.
We will also book a table at the Backbencher for anyone who wants to meet up for a pre-talk social gathering from 5:45-6:45pm. People will have to buy their own drinks and food. Contact the Wellington branch to book
Contact: wellington@gsnz.org.nz
This talk will be live streamed but not recorded: https://vuw.zoom.us/j/96764870912