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Stress drop variations of induced earthquakes at the Basel geothermal site
Author(s) -
GoertzAllmann Bettina P.,
Goertz Alex,
Wiemer Stefan
Publication year - 2011
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 - 10.1029/2011gl047498
Subject(s) - pore water pressure , geothermal gradient , geology , perturbation (astronomy) , drop (telecommunication) , pressure drop , mechanics , geotechnical engineering , geophysics , physics , telecommunications , computer science , quantum mechanics
We determine stress drops from P‐wave spectra of about 1000 earthquakes induced by hydraulic stimulation in crystalline rock for a deep heat mining project in Basel, Switzerland. We observe an increase in stress drop by about a factor of five with radial distance from 10 m to 300 m, which suggests that stress drop correlates with pore pressure perturbations due to the injection. We test this hypothesis by calculating the injection‐related pore pressure perturbation based on a simple linear pore pressure diffusion model and find a good correlation of the expected pore pressure perturbation with the estimated stress drops.