An Inversion Method for Estimating the Source Parameters of Seismic and Aseismic Events from Static Strain Data

Abstract

Summary An inversion method is developed for estimating the source parameters of seismic and aseismic events from static strain data. The inversion method consists of a non-linear least squares algorithm of Marquardt combined with an incremental procedure. The inversion method is quite stable if the strain fields are modelled by a point source in a homogeneous halfspace. The seismic moment, direction of strike, slip direction, and dip of the San Fernando earthquake of 1971 February 9, and the Gifu, Japan earthquake of 1969 September 9, have been estimated from the static strain data. The estimated parameters from the static data are in good agreement with the seismically estimated source parameters. The success with which the static strain steps may be inverted to obtain the source parameters of two seismic events suggests that static strain steps are indeed a real manifestation of the static fields associated with displacement on a fault.