Open AccessApparent break in earthquake scaling due to path and site effects on deep borehole recordings
Author(s) -
Ide Satoshi,
Beroza Gregory C.,
Prejean Stephanie G.,
Ellsworth William L.
Publication year - 2003
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jb001617
Subject(s) - borehole , seismic moment , scaling , geology , seismology , moment (physics) , rigidity (electromagnetism) , drop (telecommunication) , geophysics , geodesy , physics , geometry , geotechnical engineering , mathematics , telecommunications , fault (geology) , classical mechanics , quantum mechanics , computer science
We reexamine the scaling of stress drop and apparent stress, rigidity times the ratio between seismically radiated energy to seismic moment, with earthquake size for a set of microearthquakes recorded in a deep borehole in Long Valley, California. In the first set of calculations, we assume a constant Q and solve for the corner frequency and seismic moment. In the second set of calculations, we model the spectral ratio of nearby events to determine the same quantities. We find that the spectral ratio technique, which can account for path and site effects or nonconstant Q , yields higher stress drops, particularly for the smaller events in the data set. The measurements determined from spectral ratios indicate no departure from constant stress drop scaling down to the smallest events in our data set ( M w 0.8). Our results indicate that propagation effects can contaminate measurements of source parameters even in the relatively clean recording environment of a deep borehole, just as they do at the Earth's surface. The scaling of source properties of microearthquakes made from deep borehole recordings may need to be reevaluated.