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Response of the San Jacinto fault zone to static stress changes from the 1992 Landers earthquake

Response of the San Jacinto fault zone to static stress changes from the 1992 Landers earthquake. M. Nic Bhloscaidh and J. McCloskey School of Environmental Sciences, University of Ulster C. J. Bean School of Geological Sciences, University College Dublin. Coulomb stresses and aftershocks.

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Response of the San Jacinto fault zone to static stress changes from the 1992 Landers earthquake

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  1. Response of the San Jacinto fault zone to static stress changes from the 1992 Landers earthquake M. Nic Bhloscaidh and J. McCloskey School of Environmental Sciences, University of Ulster C. J. Bean School of Geological Sciences, University College Dublin

  2. Coulomb stresses and aftershocks Landers sequence Southern California, 1992

  3. The 1992 Landers earthquake sequence M7.1 Hector Mine 16th October 1999 M6.5 Big Bear 28th June 1992 M7.3 Landers 28th June 1992 San Andreas Fault Zone California Geological Survey M6.1 Joshua Tree 23rd April 1992 San Jacinto Fault Zone 20km

  4. Landers pre-seismicity r – pre-seismicity rate R – aftershock rate

  5. Changes in rate after Landers Mallman and Zoback (2005)

  6. The San Jacinto Fault Zone SAN JACINTO SAN BERNARDINO ANZA Sanders and Kanamori (1984)

  7. Coulomb Stress Triggering

  8. Correlation between rate changes and static stress changes San Bernardino San Jacinto Anza

  9. The Coulomb Rate-State model Dieterich, 1994

  10. Estimating the parameters of the CRS model

  11. Conclusions We find a statistically significant positive correlation between the change in rate and the magnitude of the Coulomb stress change, with a correlation coefficient of 0.76 (5.6σ). This result is an important step in the validation of Coulomb stress based methods for quantitative seismicity forecasting. The correspondence between Coulomb stress changes and observed rate changes is sensitive to strong heterogeneity in aftershock locations and orientations associated with the presence of large-scale structure in aftershock study areas. Where the regional structure is mapped, incorporating it explicitly into Coulomb stress models may improve the performance of quantitative Coulomb stress based forecasts.

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