A three-dimensional crustal seismic velocity model for southern California from a composite event method

Guoqing Lin, Peter M. Shearer, Egill Hauksson, Clifford H. Thurber

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

We present a new crustal seismic velocity model for southern California derived from P and S arrival times from local earthquakes and explosions. To reduce the volume of data and ensure a more uniform source distribution, we compute "composite event" picks for 2597 distributed master events that include pick information for other events within spheres of 2 km radius. The approach reduces random picking error and maximizes the number of S wave picks. To constrain absolute event locations and shallow velocity structure, we also use times from controlled sources, including both refraction shots and quarries. We implement the SIMULPS tomography algorithm to obtain three-dimensional (3-D) Vp and Vp/Vs structure and hypocenter locations of the composite events. Our new velocity model in general agrees with previous studies, resolving low-velocity features at shallow depths in the basins and some high-velocity features in the midcrust. Using our velocity model and 3-D ray tracing, we relocate about 450,000 earthquakes from 1981 to 2005. We observe a weak correlation between seismic velocities and earthquake occurrence, with shallow earthquakes mostly occurring in high P velocity regions and midcrustal earthquakes occurring in low P velocity regions. In addition, most seismicity occurs in regions with relatively low Vp/Vs ratios, although aftershock sequences following large earthquakes are often an exception to this pattern.

Original languageEnglish (US)
Article numberB11306
JournalJournal of Geophysical Research C: Oceans
Volume112
Issue number11
DOIs
StatePublished - Nov 4 2007
Externally publishedYes

Fingerprint

Southern California
seismic velocity
earthquake
composite materials
earthquakes
Earthquakes
Composite materials
ray tracing
arrival time
velocity structure
mines (excavations)
aftershock
refraction
quarry
tomography
method
seismicity
random errors
S-wave
explosion

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

A three-dimensional crustal seismic velocity model for southern California from a composite event method. / Lin, Guoqing; Shearer, Peter M.; Hauksson, Egill; Thurber, Clifford H.

In: Journal of Geophysical Research C: Oceans, Vol. 112, No. 11, B11306, 04.11.2007.

Research output: Contribution to journalArticle

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