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Discriminating Characteristics of Tectonic and Human-Induced Seismicity

This study examines the distinguishing features of tectonic and human-induced seismicity in various regions, including the Geysers, TauTona, San Jacinto, Coso non-geothermal, Coso geothermal, and Salton Sea. The analysis explores earthquake cluster patterns, intercurrence time, spatial distance, and the Gutenberg-Richter law. The findings successfully differentiate between tectonic and induced seismicity, providing insights into the effects of human activities on seismic events.

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Discriminating Characteristics of Tectonic and Human-Induced Seismicity

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  1. Discriminating characteristics of tectonic and human induced seismicity Ilya Zaliapin Department of Mathematics and Statistics University of Nevada, Reno Yehuda Ben-Zion Department of Earth Sciences University of Southern California USC ISC * Thursday, July 23, 2015

  2. Examined Regions: • Induced seismicity • Geysers • TauTona • Tectonic seismicity • San Jacinto • Coso non-geothermal • Mixed seismicity • Coso geothermal • Salton Sea

  3. Examined regions

  4. Earthquake cluster analysis Baiesi and Paczuski, PRE, 69, 066106 (2004) Zaliapin et al., PRL, 101, 018501(2008) Zaliapin and Ben-Zion, GJI, 185, 1288–1304 (2011) Zaliapin and Ben-Zion, JGR, 118, 2847-2864 (2013)

  5. (Fractal) dimension of epicenters Intercurrence time Spatial distance Gutenberg-Richter law Distance from an earthquake j to an earlier earthquake i : Definition: Property: [M. Baiesi and M. Paczuski, PRE, 69, 066106 (2004)] [Zaliapin et al., PRL, 101, 018501(2008)]

  6. Separation of clustered and background parts in southern California Background = weak links (as in stationary, inhomogeneous Poisson process) Clustered part = strong links (events are much closer to each other than in the background part) Zaliapin et al., PRL(2008) Zaliapin and Ben-Zion, JGR (2013)

  7. Seismicity as a flow of clusters

  8. Identification of clusters: data driven Cluster #3 Cluster #1 Cluster #2 weak link strong link Time

  9. Artifacts of catalog uncertainties Zaliapin and Ben-Zion, GJI, to appear (2015)

  10. Spatial variability of absolute horizontal error in southern California Los Angeles San Diego

  11. Artifact 1: Inflated distance-to-parent

  12. Tectonic vs Induced seismicity

  13. 2-D distribution of time and space components of the EQ distance Induced Mixed Tectonic

  14. 2-D distribution of time and space components of the EQ distance Induced Tectonic • Induced seismicity shows: • Higher intensity of repeaters • Higher background rate • Higher spatial offspring separation • Higher temporal offspring separation

  15. Temporal decay of close offspring is faster for induced seismicity

  16. Coso geothermal region: active exploration began in 1987 • Induced seismicity shows: • Less intense clustering • Higher background

  17. Coso geothermal region: active exploration began in 1987 • Tectonic: • Low background • High clustering • No repeaters • Mixed: • High background • Low clustering • Active repeaters

  18. Increase of background rate in induced seismicity (5-year moving average with value placed at the window’s end)

  19. Reduced clustering of induced seismicity

  20. Increased intensity of repeaters in induced seismicity rescaled time-to-parent for offspring within one rupture length from parent • Tectonic seismicity: • Almost no repeaters • Unimodal time distribution • Mixed seismicity: • High intensity of repeaters • Bimodal time distribution

  21. Summary Seismically active regions of three types are examined: 1 1 • Tectonic seismicity (San Jacinto and Coso non-geothermal) • Induced seismicity (Geysers and TauTona) • Mixed seismicity (Coso geothermal and Salton Sea) Induced seismicity shows: 2 2 • Higher rate of background events • Faster temporal offspring decay • Higher intensity of repeaters • Larger proportion of small clusters • Larger spatial offspring separation Reported differences successfully discriminate between tectonic and induced seismicity in Coso and Salton sea observed before and after active geothermal production 3 3 Ref: Zaliapin & Ben-Zion (2015), Discriminating characteristics of tectonic and human-induced seismicity. In review

  22. Thank you!

  23. Geysers geothermal field | 1984/01 – 2011/12 | M1.0-4.5 | 75,991 events relocated catalog of Waldhauser and Schaff [2008]

  24. TauTona golden mine, South Africa | 2004/09 – 2010/09 | M1.5-4.2 | 8,519 events catalog of Boettcher [2009]

  25. Coso geothermal | 1981/01 – 2013/12 | M1.0-4.41 | 4,412 events Relocated catalog of Hauksson et al. [2013]

  26. Salton Sea | 1981/01 – 2013/12 | M1.5-5.11 | 6,018 events Relocated catalog of Hauksson et al. [2013]

  27. Coos non-geothermal | 1981/01 – 2013/12 | M1.0-5.75 | 56,801 events Relocated catalog of Hauksson et al. [2013]

  28. San Jacinto | 1981/01 – 2013/12 | M1.0-5.43 | 39,768 events Relocated catalog of Hauksson et al. [2013]

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