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Source duration of stress and water‐pressure induced seismicity derived from experimental analysis of P wave pulse width in granite
Author(s) -
Masuda Koji
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50691
Subject(s) - geology , stress (linguistics) , induced seismicity , seismology , pulse (music) , overburden pressure , fault (geology) , fracture (geology) , pore water pressure , waveform , cylinder stress , mineralogy , geotechnical engineering , materials science , composite material , optics , physics , ultimate tensile strength , philosophy , linguistics , quantum mechanics , voltage , detector
Pulse widths of P waves in granite, measured in the laboratory, were analyzed to investigate source durations of rupture processes for water‐pressure induced and stress‐induced microseismicity. Water was injected into a dry granite sample under constant axial stress of about 70% of fracture strength and a confining pressure of 40 MPa. After the effects of event size and hypocentral distance were removed from observed pulse widths, the ratio of the scaled source durations of water‐pressure induced and stress‐induced microseismicity was 0.52. The difference in the scaled source durations between water‐pressure induced and stress‐induced microseismicity suggests that water‐pressure induced microseismicity involves a greater rupture velocity or a more equidimensional fault geometry than stress‐induced microseismicity. These results suggest that pulse width analysis of P waveforms can be used to distinguish water‐pressure induced events from those induced by regional stress and to characterize the faulting process.