Tiwi Micro-Earthquake (MEQ) Monitoring (1987-2005)

Abstract

Continuous monitoring of the Tiwi geothermal field since 1987 shows that majority of the MEQ activity is located either coincident with the production area or near the Southeast Hot Brine Injection System (SEHBIS). The spatial and temporal correlations of MEQs with production and injection are seen over most geothermal fields (e.g. Kakkonda, Japan: Coso and The Geysers, California).

The Tiwi field can be divided into four sectors or regions based on the major MEQ clusters. These sectors are referred to as the Matalibong-Bariis (Mat-Bar) Area, the Kapipihan (Kap) Area, the Naglagbong (Nag) Area, and the SEHBIS. Theses areas are characteriqed seismically by distinct trends in the depths and horizontal distribution of the MEQ clusters, rates of occurrence of the MEQs over time, and probable inducing mechanism (e.g. production, injection, or groundwater influx).