1 / 40

Ilya Zaliapin

Spatio-temporal evolution of seismic clusters in southern and central California. Ilya Zaliapin. Department of Mathematics and Statistics University of Nevada, Reno. Yehuda Ben-Zion Department of Earth Sciences University of Southern California. SAMSI workshop “ Dynamics of Seismicity ”

efuru
Download Presentation

Ilya Zaliapin

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spatio-temporal evolution of seismic clusters in southern and central California Ilya Zaliapin Department of Mathematics and Statistics University of Nevada, Reno Yehuda Ben-Zion Department of Earth Sciences University of Southern California SAMSI workshop “Dynamics of Seismicity” Thursday, October 10, 2013

  2. Outline Earthquake clusters: existence, detection, stability 1 1 Clusters in southern California 2 2 • Main types of clusters • Topological cluster characterization Cluster type vs. physical properties of the lithosphere 3 3 Evolution of clustering with relation to large events 4 4

  3. Data • Southern California catalog: Hauksson, Yang, Shearer(2012) available from SCEC data center; 111,981 earthquakes with m ≥ 2 • Heat flow data from www.smu.edu/geothermal

  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) Zaliapin and Ben-Zion, JGR, 118, 2865-2877 (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 Earthquake j Parent (nearest neighbor) i Zaliapin et al., PRL (2008) Zaliapin and Ben-Zion, JGR (2012)

  7. Background and clustered parts in models Homogeneous Poisson process ETAS model Zaliapin et al., PRL (2008) Zaliapin and Ben-Zion, JGR (2013)

  8. 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)

  9. Seismicity as a flow of clusters

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

  11. Identification of event types: problem driven Foreshocks Mainshock Single Aftershocks Time

  12. Quality and stability of cluster identification

  13. ETAS declustering: Example 29,671 events 9,536 mainshocks

  14. Main types of EQ clusters • Burst-like clusters • Represent brittle fracture. Large b-value (b=1), small number of events, small proportion of foreshocks, short duration, small area, isotropic spatial distribution. • Tend to occur in regions with low heat flow, non-enhanced fluid content, relatively large depth => increased effective viscosity. • Swarm-like clusters • Represent brittle-ductile fracture. Small b-value (b=0.6), large number of events, large proportion of foreshocks, long duration, large area, anisotropic channel-like spatial pattern. • Tend to occur in regions with high heat flow, increased fluid content, relatively shallow depth => decreased effective viscosity. • Singles • Highly numerous in all regions; some but not all are related to catalog resolution. • Clusters of the largest events • Most prominent clusters; object of the standard cluster studies. Not representative of the majority of clusters (mixture of types 1-2).

  15. Swarm vs. burst like clusters: Topologic representation M5.51 M5.75 Burst-like Swarm-like M5.51 M5.75 Time Time L= 417, tree depth = 9, ave. depth = 3.8 L= 572, tree depth = 44, ave. depth = 30.3

  16. Average leaf depth (number of generations from a leaf to the root): Bimodal structure ETAS model Large topological depth: Swarm-like clusters Small topological depth: Burst-like clusters HYS (2012), mM ≥ 2

  17. Cluster type vs. physical properties of the crust

  18. Heat flow in southern California http://www.smu.edu/geothermal

  19. Preferred spatial location of burst/swarm like clusters 195 clusters with m ≥ 4, N ≥ 10; spatial average within 50 km

  20. Moment of foreshocks relative to that of mainshock 195 clusters with m ≥ 4, N ≥ 10; spatial average within 50 km

  21. Family size 112 Δ- clusters with m ≥ 4, N ≥ 10; spatial average within 50 km

  22. Evolution of seismic clustering

  23. Statistical analysis of premonitory patterns: zero-level approach Space D-zone X-zone D-zone X-zone N-zone Time

  24. Topological depth (average leaf depth) All mainshocks D = 2 years, X = 1 year, R = 200 km, M=6.5 mainshocks with m>3 are examined

  25. Topological depth (average leaf depth) ANOVA p =7x10-7 : Significant difference Large families, N > 20 Δ = X = 3 years, R = 100km m > 3, N > 20

  26. Proportion of families All mainshocks Δ = X = 2 years, R = 100km m > 3

  27. Proportion of large families (N>=5) Families (N > 1) Δ = X = 2 years, R = 100km m > 3, N >1

  28. Large earthquakes in California, M6.5 4) Hector Mine, M7.1, 1999 3) Northridge, M6.7, 1994 2) Landers, M7.3, 1992 1) Superstition Hills, M6.6, 1987 5) El Mayor Cucapah, M7.2, 2010

  29. L L EMC

  30. “San Jacinto Fault” HM L N SH EMC

  31. “San Jacinto Fault” EMC SH Families with size L > 10 L N HM Families with 3 < m < 4

  32. 100 km from Superstition Hills, M6.6 of 1987 SH L N HM EMC Topological depth d > 6, mainshock m< 5

  33. Salton Trough

  34. Salton Trough SH L N HM EMC Average leaf depth > 1, Family size > 5

  35. Baja California

  36. Baja California SH L N HM EMC Average leaf depth > 1, Family size > 5

  37. El Mayor Cucapah, M7.2 R < 5 km R < 20 km R < 100 km R < 300 km Average leaf depth > 1, Family size > 5

  38. 20 km from Landers, M7.3 of 1992 SH L N HM EMC Landers, M7.3 of 1992 Remote foreshock to Hector Mine, M7.1 of 1999 Remote aftershock of Superstition Hill, M6.6 of 1987 Topological depth d > 5 In this region: 613 mainshocks; 139 families; 11 mainshocks/10 families with m>3.5

  39. Summary Seismic clusters in southern California 1 1 • Four types of clusters: • Burst-like clusters • Swarm-like clusters • Singles • Largest regional clusters • Topological cluster characterization Spatial variability: Relation to physical properties of the crust 2 2 • Swarm-like clusters <-> decreased effective viscosity • Burst-like clusters <-> increased effective viscosity 3 3 Temporal variability: Relation to large events

  40. Thank you!

More Related