The Study and Simulation of the Non-Seismic Tsunamis (II)

At the end of 2018, two consecutive tsunami events occurred in Indonesia. The first one was the 2018 Sulawesi earthquake and tsunami (SET) on September 28. The other was the 2018 Sunda Strait tsunami (SST) on December 22. Thesetwo tsunamis have one thing in common: they are not traditional earthquake tsunamis. The SET occurred with an earthquake of magnitude 7.5. However, only by an earthquake of this magnitude could not trigger a tsunami of 7 meters high or higher in this event. The SST was not event triggered by an earthquake. The tsunami suddenly arrived at about 9:27 PM in the local time. The causes of these two tsunami events still remain unknown. A submarine landslide or an additionalseabed vertical displacement may play a role. To gain a deeper understanding of these tsunami events, finding the location of the tsunami source is especially important. The new research this year will follow the results from last year and apply the developed methods of impact intensity analysis method (IIA) and tsunami arrival time analysis (TATA) to analyzing the tsunami source in the SET event. The IIA method can quickly filter out the areas with low impacts of the tsunami sources and effectively reduce the number of tsunami scenarios. However, for a tsunami with a strong direction, it is less easy to grasp. The newly developed Tsunami Time Analysis Method (TATA) can overcome this weakness. The non-seismic tsunami is mainly caused by landslides on the seabed or submarine volcanic landslides. In the history of Taiwan, the 1867 Keelung tsunami and the 1781 Kaohsiung-Pingtung tsunami were possibly non-seismic tsunami events. In addition to analyzing the SET, this project will also conduct an analysis of the above-mentioned historical tsunami events in Taiwan. The discontinuous bi-viscous model (DBM) will be used to perform the complete process of landslide-generated tsunamis. It is hoped that through the profound understanding of the tsunami sources, we will be able to tackle the potential nonseismic tsunami disaster in Taiwan.