Design of an Integrated Borehole Seismic and Geodetic Sensor

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

The understanding of tectonic and earthquake processes depends upon observations of earth motions that span periods from years to fractions of a second and amplitudes from nanometers to meters. Up until now such observations came from a variety of instruments such as seismometers, geodetic-quality GPS receivers, gravimeters, and strain meters. Even as GPS networks are reaching up to nearly seismic frequencies and observatory quality seismometers extend down into the geodetic range, the multiple instruments required are complex and expensive to deploy and operate. This award will fund the concept and design of a combined instrument that will provide much of the relevant information. This instrument concept will meet the stringent requirements of the Global Seismographic Network while providing geodetic measurements with significantly lower noise than GPS. Housed in a simple borehole sonde, the instrument will be inexpensive to construct, install, and operate. If our expectations are met it will become practical to significantly expand the network of geodetic/seismic observations. Locations in which both seismic and geodetic data are relevant to socially-important problems include volcanoes, areas of subsidence, oil fields, and CO2 sequestration The proposed instrument will provide low noise and extremely broadband data in such settings, enhancing the ability to understand such processes as induced seismicity, reservoir dynamics, and pre-eruption behavior.