Analysis of Seismic Activity Through Point-Process Modeling

Thursday, June 13, 2002 - 9:30am - 10:30am
Keller 3-180
Yosihiko Ogata (The Institute of Statistical Mathematics)
The occurrence times of earthquakes can be considered to be a point process, and suitable modeling of the conditional intensity function of point process is useful for the investigation of various statistical features of seismic activity. This talk reviews likelihood-based estimation of models and residual analysis of the data. Special emphasis is placed on the aftershock analysis based on the modified Omori formula and on its extension to the Epidemic Type Aftershock-Sequence (ETAS) model. Applications include the analysis and explorations of seismic quiescence as a precursor to a large earthquake, and speculation of a possible physical mechanism based on the Coulomb's stress changes. Then, the ETAS model is extended to the hierarchical space-time ETAS (HIST-ETAS) model, which estimate regional characteristics of seismic activity and is used to explore anomalous features such as the spatial seismicity gap.