Possible stick-slip behavior before the Rausu landslide inferred from repeating seismic events

Abstract

A precursory sequence of repeating earthquakes was recorded before the Rausu landslide in Hokkaido, Japan, on 24 April 2015. There were two seismic sequences with each consisting of very similar waveforms and leading up to significant landslide movements. The nearly identical waveform shapes indicate similar source locations and mechanisms, so repeated events originated on a particular small area. This sequence is interpreted as stick-slip movement on a small patch leading up to the larger landslide failure. Our observations show that heterogeneous structure, such as asperities on the slip surface, can play an important role in the initiation of landslides, adding a new aspect to the conventional understanding of mechanisms controlling large mass movements.