Seismic reflection evidence for seismogenic low-angle faulting in southeastern Arizona

Abstract

Research Article| July 01, 1992 Seismic reflection evidence for seismogenic low-angle faulting in southeastern Arizona Roy A. Johnson; Roy A. Johnson 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Kenneth L. Loy Kenneth L. Loy 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Author and Article Information Roy A. Johnson 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Kenneth L. Loy 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (7): 597–600. https://doi.org/10.1130/0091-7613(1992)020<0597:SREFSL>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 MailTo Tools Icon Tools Get Permissions Search Site Citation Roy A. Johnson, Kenneth L. Loy; Seismic reflection evidence for seismogenic low-angle faulting in southeastern Arizona. Geology 1992;; 20 (7): 597–600. doi: https://doi.org/10.1130/0091-7613(1992)020<0597:SREFSL>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 Focal mechanisms for large (M >6) earthquakes in extensional terranes suggest that seismogenic normal faults have dips that range from ∼30° to ∼70°. Geologic relations suggest that low-angle faults have accommodated large-scale upper-crustal extension. These disparate observations are often reconciled by arguments that low-angle faults move aseismically or rotate to low angles from initially high angles. Seismic reflection data from the Tucson basin in southeast Arizona image a low-angle normal fault (the Santa Rita fault) that crops out along the trend of late Quaternary fault scarps caused by large- magnitude (M ∼6.7-7.6) earthquakes.Velocity-independent dip analysis from shot records of the Santa Rita fault indicates that it has a true dip of ∼20° to a depth of at least 6 km. This observation suggests that low-angle extensional faults indeed may be seismogenic and that actual mechanisms for accommodation of upper-crustal extension depend on local conditions of stress and preexisting geologic structure. 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.