Abstract

A small aperture seismic array has been deployed along a 30-km stretch of the San Jacinto fault in the vicinity of the town of Anza, California. The array was installed to study specifically the scaling laws of body-wave spectra, the character of high-frequency ground motion, the physical interpretation of seismic stress drops, and the interaction of earthquakes. This region was chosen for these studies due to its high rate of seismic activity in the 2 ≦ M ≦ 4.5 range, the likelihood of a M > 6 event in the next decade, and the existence of the Southern California Batholith on either side of the fault, reducing problems associated with attenuation and large scale anisotropy. These studies employ an instrument package with a frequency response of 100 Hz, a dynamic range of 138 dB, a sampling rate of 250 times per second per component, and a 16-bit A/D converter. The array consists of 10 three-component stations, telemetered via digital VHF radio to a nearby mountain peak and thence via a microwave link to La Jolla, California. A minicomputer system monitors the array's performance, detects events, and records data upon demand. Initial results demonstrate the feasibility of digital transmission with an inherent increase in data quality over analog systems.

First Page Preview

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