Three-dimensional tomography of the 1992 southern California earthquake sequence: Constraints on dynamic earthquake rupture?

Abstract

Research Article| May 01, 1993 Three-dimensional tomography of the 1992 southern California earthquake sequence: Constraints on dynamic earthquake rupture? Jonathan M. Lees; Jonathan M. Lees 1Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511 Search for other works by this author on: GSW Google Scholar Craig Nicholson Craig Nicholson 2Institute for Crustal Studies, University of California, Santa Barbara, California 93106 Search for other works by this author on: GSW Google Scholar Author and Article Information Jonathan M. Lees 1Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511 Craig Nicholson 2Institute for Crustal Studies, University of California, Santa Barbara, California 93106 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1993) 21 (5): 387–390. https://doi.org/10.1130/0091-7613(1993)021<0387:TDTOTS>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jonathan M. Lees, Craig Nicholson; Three-dimensional tomography of the 1992 southern California earthquake sequence: Constraints on dynamic earthquake rupture?. Geology 1993;; 21 (5): 387–390. doi: https://doi.org/10.1130/0091-7613(1993)021<0387:TDTOTS>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Tomographic inversion of P-wave arrival times from aftershocks of 1992 southern California earthquakes is used to produce three dimensional images of subsurface velocity. The preliminary 1992 data set, augmented by the 1986 M 5.9 North Palm Springs sequence, consists of 6458 high-quality events recorded by the permanent regional network—providing 76306 raypaths for inversion. The target area consisted of a 104 x 104 x 32 km3 volume divided into 52 x 52 x 10 rectilinear blocks. Significant velocity perturbations appear to correlate with rupture properties of recent major earthquakes. Preliminary results indicate that a low-velocity anomaly separates the dynamic rupture of the M 6.5 Big Bear event from the M 7.4 Landers main shock; a similar low-velocity region separates the M 6.1 Joshua Tree sequence from the Landers rupture.High-velocity anomalies occur at or near nucleation sites of all four recent main shocks (North Palm Springs-Joshua Tree-LandersBig Bear). A high-velocity anomaly is present along the San Andreas fault between 5 and 12 km depth through San Gorgonio Pass; this high-velocity area may define an asperity where stress is concentrated and where future large earthquakes may begin. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.