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The theory and prototype development of a stress-monitoring system

January 1, 1990

A new approach has been developed by which changes in rock stress can be measured directly. The measurement of stress change depends on the reaction of a slender, compliant cavity to the transient variations of rock stress about the cavity. A liquid-filled pressurized cell, emplaced in the cavity, provides the means by which changes in pressure can be monitored. The change in pressure in the cell is equivalent to the change in rock stress in the direction normal to the cell if the compliance contrast between cavity and rock is large and the aspect ratio of the cavity is small. Earthquake-related variations in the stress field in a highly fractured quartz-monzonite stock have been observed to occur in a characteristic way prior to a microseismic event. The precursory stress change (decompression followed by compression) lasted about 5 hours and led directly to a stress drop of 15 × 10−3 bar. Seismic noise monitored during the same period of time suggests that failure in the fractured rock mass resulted from rapid encroachment of meltwater and subsequent increase in fluid pressure.

Publication Year 1990
Title The theory and prototype development of a stress-monitoring system
DOI 10.1785/BSSA0800010197
Authors H.S. Swolfs, J.B. Walsh
Publication Type Article
Publication Subtype Journal Article
Series Title Bulletin of the Seismological Society of America
Index ID 70015912
Record Source USGS Publications Warehouse