Analysis of Foreshock Sequences in California and Implications for Earthquake Triggering
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We analyze foreshock activity in California and compare observations with simulated catalogs based on a branching aftershock-triggering model. We first examine foreshock occurrence patterns for isolated \(M \ge 5\) earthquakes in southern California from 1981 to 2011 and in northern California from 1984 to 2009. Among the 64 \(M \ge 5\) mainshocks, excluding 3 swarms and 3 doubles, 53 % of the rest are preceded by at least one foreshock within 30 days and 5 km. Foreshock occurrence appears correlated with mainshock faulting type and depth. Foreshock area is correlated with the magnitude of the largest foreshock and the number of foreshocks, however, it is not correlated with mainshock magnitude. We then examine the occurrence pattern of all seismicity clusters without a minimum magnitude requirement, and the possibility that they are “foreshocks” of larger mainshocks. Only about 30 % of the small clusters lead to a larger cluster. About 66 % of the larger clusters have foreshock activities, and the spatial distribution pattern is similar to \(M \ge 5\) mainshocks, with lower occurrence rates in the Transverse Range and central California and higher occurrence rates in the Eastern California Shear Zone and the Bay Area. These results suggest that foreshock occurrence is largely controlled by the regional tectonic stress field and fault zone properties. In special cases, foreshock occurrence may be useful for short-term forecasting; however, foreshock properties are not reliably predictive of the magnitude of the eventual “mainshock”. Comparison with simulated catalogs suggest that the “swarmy” features and foreshock occurrence rate in the observed catalogs are not well reproduced from common statistical models of earthquake triggering.
KeywordsEarthquake Swarm Interplate Earthquake Precursory Activity Synthetic Catalog Foreshock Activity
We thank the Northern California Seismic Network, the U.S. Geological Survey, Menlo Park, and the Berkeley Seismological Laboratory, University of California, Berkeley for providing a moment tensor catalog. We thank the Global CMT Project for providing moment tensor solutions. We thank Richard Sibson for discussion on precursory behavior based on stress analysis. The maps are generated using the GMT software package.
- Abercrombie, R. E., and J. Mori (1996), Occurrence patterns of foreshocks to large earthquakes in the western united states, Nature, 381(6580), 303–307.Google Scholar
- Bath, M. (1965), Lateral inhomogeneities of upper mantle, Tectonophysics, 2(6), 483.Google Scholar
- Beroza, G. C., and W. L. Ellsworth (1996), Properties of the seismic nucleation phase, Tectonophysics, 261(1–3), 209–227, doi: 10.1016/0040-1951(96)00067-4.
- Bouchon, M., V. Durand, D. Marsan, H. Karabulut, and J. Schmittbuhl (2013), The long precursory phase of most large interplate earthquakes, Nature Geosci, 6, 299–302, doi: 10.1038/ngeo1770.
- Chen, X., and P. Shearer (2013), California foreshock sequences suggest aseismic triggering process, Geophys. Res. Lett., 40, 2602–2607, doi: 10.1002/grl.50444.
- Chen, X., P. M. Shearer, and R. Abercrombie (2012), Spatial migration of earthquakes within seismic clusters in southern California: Evidence for fluid diffusion, J. Geophys. Res., 117(B04301), doi: 10.1029/2011JB008973.
- Dodge, D. A., G. C. Beroza, and W. L. Ellsworth (1996), Detailed observations of California foreshock sequences: Implications for the earthquake initiation process, Journal of Geophysical Research-Solid Earth, 101(B10), 22,371–22,392.Google Scholar
- Ellsworth, W. L., and G. C. Beroza (1995), Seismic evidence for an earthquake nucleation phase, Science, 268(5212), 851–855, doi: 10.1126/science.268.5212.851.
- Felzer, K. R., R. E. Abercrombie, and G. Ekstrom (2004), A common origin for aftershocks, foreshocks, and multiplets, Bulletin of the Seismological Society of America, 94(1), 88–98, doi: 10.1785/0120030069.
- Hainzl, S., and T. Fischer (2002), Indications for a successively triggered rupture growth underlying the 2000 earthquake swarm in vogtland/nw bohemia, Journal of Geophysical Research-Solid Earth, 107(B12), 2338, doi: 10.1029/2002jb001865.
- Hainzl, S. (2003), Self-organization of earthquake swarms, Journal of Geodynamics, 35(1–2), 157–172.Google Scholar
- Hardebeck, J. L., and P. M. Shearer (2003), Using s/p amplitude ratios to constrain the focal mechanisms of small earthquakes, Bulletin of the Seismological Society of America, 93(6), 2434–2444.Google Scholar
- Hauksson, E., W. Yang, and P. M. Shearer (2012), Waveform relocated earthquake catalog for southern California (1981 to june 2011), Bulletin of the Seismological Society of America, 102(5), 2239–2244, doi: 10.1785/0120120010.
- Helmstetter, A., D. Sornette, and J. R. Grasso (2003), Mainshocks are aftershocks of conditional foreshocks: How do foreshock statistical properties emerge from aftershock laws, Journal of Geophysical Research-Solid Earth, 108(B1), 24, doi: 10.1029/2002jb001991.
- Helmstetter, A., Y. Y. Kagan, and D. D. Jackson (2005), Importance of small earthquakes for stress transfers and earthquake triggering, Journal of Geophysical Research-Solid Earth, 110(B5), 13, doi: 10.1029/2004jb003286.
- Jones, L. M. (1984), Foreshocks (1966-1980) in the San-Andreas system, California, Bulletin of the Seismological Society of America, 74(4), 1361–1380.Google Scholar
- Kato, A., and S. Nakagawa (2014), Multiple slow-slip events during a foreshock sequence of the 2014 Iquique, Chile mw8.1 earthquake, Geophysical Research Letters, 41, doi: 10.1002/2014GL061138.
- Kato, A., K. Obara, T. Igarashi, H. Tsuruoka, S. Nakagawa, and N. Hirata (2012), Propagation of slow slip leading up to the 2011 m-w 9.0 tohoku-oki earthquake, Science, 335(6069), 705–708, doi: 10.1126/science.1215141.
- Mogi, K. (1963), Some discussions on aftershocks, foreshocks and earthquake swarms - the fracture of a semi-infinite body casued by an inner stress origin and its relation to the earthquake phenomena, Bulletin of the Earthquake Research Institute, 41, 615–658.Google Scholar
- McGuire, J. J., M. S. Boettcher and T. H. Jordan (2005), Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults, Nature, 434.Google Scholar
- Mignan, Arnaud (2014), The debate on the prognostic value of earthquake foreshocks: A meta-analysis, Scientific reports, 4(4099), doi: 10.1038/srep04099.
- Ogata, Y. (1999), Seismicity analysis through point-process modeling: A review, Pure and Applied Geophysics, 155(2–4), 471–507.Google Scholar
- Reasenberg, P. (1985), Second-order moment of central California seismicity, J. Geophys. Res., 90, pp. 5479–5495.Google Scholar
- Reasenberg, P. (1999), Foreshock occurrence before large earthquakes, J. Geophys. Res., 104(B3), 4755–4768.Google Scholar
- Shearer, P. M. (2009), Introduction to Seismology, second edition, Cambridge University Press.Google Scholar
- Shearer, P. M., and G. Q. Lin (2009), Evidence for mogi doughnut behavior in seismicity preceding small earthquakes in southern California, Journal of Geophysical Research-Solid Earth, 114(B01318), doi: 10.1029/2008jb005982.
- Shearer, P. M., G. A. Prieto, and E. Hauksson (2006), Comprehensive analysis of earthquake source spectra in southern California, Journal of Geophysical Research-Solid Earth, 111(B06303), doi: 10.1029/2005jb003979.
- Shearer, P. M. (2012a), Self-similar earthquake triggering, Båth’s law, and foreshock/aftershock magnitudes: Simulations, theory, and results for southern California, J. Geophys. Res., 117(B06310), doi: 10.1029/2011jb008957.
- Shearer, P. M. (2012b), Space-time clustering of seismicity in California and the distance dependence of earthquake triggering, J. Geophys. Res., 117(B10306), doi: 10.1029/2012JB009471.
- Sibson, R. H. (1993), Load-strengthening versus load-weakening faulting, J. Struct. Geol., 15(2), 123–128.Google Scholar
- Toda, S., R. S. Stein, G. C. Beroza, and D. Marsan (2012), Aftershocks halted by static stress shadows, Nature Geosci, 5(410–413), doi: 10.1038/ngeo1465.
- Vidale, J. E., and P. M. Shearer (2006), A survey of 71 earthquake bursts across southern California: Exploring the role of pore fluid pressure fluctuations and aseismic slip as drivers, Journal of Geophysical Research-Solid Earth, 111(B05312), doi: 10.1029/2005jb004034.
- Waldhauser, F., and D. P. Schaff (2008), Large-scale relocation of two decades of northern California seismicity using cross-correlation and double-difference methods, J. Geophys. Res., 113(B08311), doi: 10.1029/2007JB005479.
- Yamashita, T. (1999), Pore creation due to fault slip in a fluid-permeated fault zone and its effect on seismicity: Generation mechanism of earthquake swarm, Pure and Applied Geophysics, 155(2–4), 625–647.Google Scholar
- Yang, W., E. Hauksson, and P. M. Shearer (2012), Computing a large refined catalog of focal mechanisms for southern California (1981–2010): Temporal stability of the style of faulting, Bulletin of the Seismological Society of America, 102(3), pp. 1179–1194, doi: 10.1785/0120110311.