Earthquake Clustering and Statistics

Earthquakes cluster strongly in space and time. Much of this can be explained by earthquake-to-earthquake triggering, which leads to aftershock sequences following large events. However, other earthquake clusters, such as swarms and many foreshock sequences, suggesting an underlying physical driving mechanism. Understanding these processes requires studying large earthquake catalogs to unravel the underlying statistical properties that control temporal and spatial variations in earthquake occurrence probability and provide clues regarding earthquake initiation.

Relevant papers with contributions from my group include:

  1. Ross, Z. E., D. T. Trugman, E. Hauksson, and P. M. Shearer, Searching for hidden earthquakes in Southern California, Science, 364, 767-771, doi: 10.1126/science.aaw6888, 2019.
  2. Fan, W., and P. M. Shearer, Local near instantaneously dynamically triggered aftershocks of large earthquakes, Science, 353, 1133-1136, doi: 10.1126/science.aag0013, 2016. REPRINT
  3. Zhang, Q., and P. M. Shearer, A new method to identify earthquake swarms applied to seismicity near the San Jacinto Fault, California, Geophys. J. Int., 205, 995-1005, doi: 10.1093/gji/ggw073, 2016. (PDF)
  4. Trugman, D.T., P. M. Shearer, A. A. Borsa, and Y. Fialko, A comparison of long-term changes in seismicity at the Geysers, Salton Sea, and Coso geothermal fields, J. Geophys. Res., 121, 225-247, doi: 10.1002/2015JB012510, 2016. (PDF)
  5. Zhan, Z., and P. M. Shearer, Possible seasonality in large deep-focus earthquakes, Geophys. Res. Lett., 42, 7366-7373, doi: 10.1002/2015GL065088, 2015. (PDF)
  6. Wang, W., and P. M. Shearer, No clear evidence for localized tidal periodicities in earthquakes in the central Japan region, J. Geophys. Res., 120, 6317-6328, doi: 10.1002/2015JB011937, 2015. (PDF)
  7. Chen, X., and P. M. Shearer, Analysis of foreshock sequences in California and implications for earthquake triggering, Pure Appl. Geophys., doi: 10.1007/s00024-015-1103-0, 2015. (PDF)
  8. Chen, X., and P. M. Shearer, California foreshock sequences suggest aseismic triggering process, Geophys. Res. Lett., 40, doi:10.1002/grl.50444, 2013. (PDF)
  9. Shearer, P. M., Reply to comment by S. Hainzl on "Self-similar earthquake triggering, Bath's Law, and foreshock/aftershock magnitudes: Simulations, theory and results for southern California," J. Geophys. Res., 118, doi: 10.1002/jgrb.50133, 2013. (PDF)
  10. Shearer, P. M., and P. B. Stark, Global risk of big earthquakes has not recently increased, Proc. Nat. Acad. Sci., 109, 717-721, www.pnas.org/cgi/doi/10.1073/pnas.1118525109, 2012. (PDF)
  11. Chen, X., P. M. Shearer, and R. E. Abercrombie, Spatial migration of earthquakes within seismic clusters in Southern California: Evidence for fluid diffusion, J. Geophys. Res., 117, B04301, doi:10.1029/2011JB008973, 2012. (PDF)
  12. Shearer, P. M., Self-similar earthquake triggering, Bath's law, and foreshock/aftershock magnitudes: Simulations, theory, and results for southern California, J. Geophys. Res., 117, B06310, doi: 10.1029/2011JB008957, 2012. (PDF)
  13. Shearer, P. M., Space-time clustering of seismicity in California and the distance dependence of earthquake triggering, J. Geophys. Res., 117, B10306, doi: 10.1029/2012JB009471, 2012. (PDF)
  14. Chen, X., and P. M. Shearer, Comprehensive analysis of earthquake source spectra and swarms in the Salton Trough, California, J. Geophys. Res., 116, doi:10.1029/2011JB008263, 2011. (please note correction at J. Geophys. Res., 118, doi: 10.1002/jgrb.50098, 2013) (PDF)
  15. Shearer, P. M., and G. Lin, Evidence for Mogi doughnut behavior in seismicity preceding small earthquakes in southern California, J. Geophys. Res., 114, doi: 10.1029/2009JB005982, 2009. (PDF)
  16. Vidale, J.E., K.L. Boyle, and P.M. Shearer, Crustal earthquake bursts in California and Japan: Their patterns and relation to volcanoes, Geophys. Res. Lett., 33, L20313, doi:10.1029/2006GL027723, 2006. (PDF)
  17. Vidale, J. E., and P. M. Shearer, A survey of 71 earthquake bursts across southern California: Exploring the role of pore fluid pressure fluctuations and aseismic slip as drivers, J. Geophys. Res., 111, B05312, doi:10.1029/2005JB004034, 2006. (PDF)
  18. Shearer, P.M., Evidence for a fault at 18 km depth beneath Oak Ridge, southern California, from a cluster of small earthquakes, Bull. Seismol. So. Am., 88, 1327-1336, 1998.