abstract

A precise model for relocation of earthquakes of a region or the multiple ruptures of a large earthquake, using P-wave arrival-time difference data, is given by the equation of condition of the standard single-event location model (Geiger model). The use of P-wave arrival-time differences provides ray path redundancies from earthquakes in a limited source region to a given station set. Thus, this relocation model implicitly compensates certain time anomalies caused by lateral velocity heterogeneities, leading to good relative locations without the requirement of a set of master residuals. Because the solution vector of the arrival-time difference model may be significantly nonzero at convergence, the second-order terms of the Geiger model are derived and used to determine the size of the neighborhood in which this arrival-time difference formulation will give acceptable location resolution. Evaluation of these second-order terms shows that accurate, teleseismically-determined relative locations are possible with the arrival-time difference method for events within 212° distance of a reference earthquake's epicenter. The use of this relocation method with teleseismic data requires independent depth information. The cosine term relative location model, often used with arrival-time difference data to graphically locate multiple ruptures, is an approximation to the Geiger model as it is used here.

First Page Preview

First page PDF preview
You do not currently have access to this article.