HR: 1340h
AN: S23A-0300    [Abstracts]
TI: Analyzing earthquake clustering features by stochastic reconstruction -- foreshocks
AU: * Zhuang, J
EM: zhuangjc@ism.ac.jp
AF: Institute of Statistical Mathematics, 4-6-7 Minami Azabu, Minato-Ku, Tokyo, 106-8569 Japan
AU: Ogata, Y
EM: ogata@ism.ac.jp
AF: Institute of Statistical Mathematics, 4-6-7 Minami Azabu, Minato-Ku, Tokyo, 106-8569 Japan
AB: The ETAS model has been proved to be able to be used the first approximation for describe the earthquake clustering features (Zhuang et al 2004, JGR, 109, No. B5, B05301, doi:10.1029/2003JB002879). This model classifies the seismicity into two components, the background and the cluster, where each earthquake event, no matter if it is from the background component (usually assumed to be a space-time Poisson process, stationary or non-stationary, homogeneous or non-homogeneous) or generated by another event, produces (triggers) its own offspring (aftershocks) according to some branching rules. Its conditional intensity function at the space-time-magnitude location $(t, x, y, M)$, has the form of $$\lambda(t,x,y,M|\hit)=J(M)\left[\mu(x,y)+\sum_{i:t_ii, 0, &~~~\mbox{otherwise}, \end{array} \right ., $$ and its probability of being produced from background to be the relative contribution of the background rate, $$\varphi_j= \frac {\mu(x_j,y_j)J(M_j)}{\lambda(t_j,x_j,y_j,M_j| {\cal H}_{t_j})}.$$ These probabilities can be used to realize the family trees of earthquakes stochastically. Thus, a foreshock is naturally defined as a background event that has at least one offspring of larger magnitude, direct or indirect, and a mainshock is defined as the biggest event in the family tree. With this new definition we studied the characteristics of foreshock features and their relationship to mainshocks.
DE: 7221 Paleoseismology
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 7209 Earthquake dynamics and mechanics
DE: 3220 Nonlinear dynamics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting