統計数理研究所

場所 (Location): 統計数理研究所 D312A号室 /
Room D312A @ Institute of Statistical Mathematics

講演者 (Speaker): Martha Kane Savage
(Professor of Geophysics, SGEES Victoria University of Wellington)

講演題目 (Title): Towards Predicting Earthquakes and Volcanic Eruptions using Statistical Techniques

概要 (Abstract): Predicting natural hazards is fraught and statistical techniques are necessary to put such studies on a firm standing. Here we discuss two methods that we have applied to volcanic areas. Analysis of the rates of earthquake activity (CURATE) is used to determine the characteristics of earthquake swarms to try to determine how they develop over time. The technique compares favourably to other declustering techniques and allows us to consider whether some swarms are triggered by underlying processes that create diffuse seismicity that is not well modelled by Omori's law. We also analyse waveforms of earthquakes to determine seismic anisotropy, which depends upon stress orientation and magnitude, which in turn can be influenced by earthquake and volcanic activity. Seismic waves travel faster when their particle motion is along the cracks, which orient with the principal stress direction. At volcanoes around the world, we discovered significant changes in seismic anisotropy strength and orientation that correlate with magma movement. Detecting and evaluating such changes is complicated by scattered measurements, which sometimes have 90 degree ambiguities and we have been considering ways to make the techniques more robust. These observations will provide the data that may eventually lead to prediction tools.