Tectonics of the Intermountain Seismic Belt, Western United States: Microearthquake Seismicity and Composite Fault Plane Solutions

Research Article| January 01, 1972 Tectonics of the Intermountain Seismic Belt, Western United States: Microearthquake Seismicity and Composite Fault Plane Solutions MARC L SBAR; MARC L SBAR Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar MUAWIA BARAZANGI; MUAWIA BARAZANGI Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar JAMES DORMAN; JAMES DORMAN Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar CHRISTOPHER H SCHOLZ; CHRISTOPHER H SCHOLZ Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar ROBERT B SMITH ROBERT B SMITH Department of Geological and Geophysical Sciences, University of Utah, Salt Lake City, Utah 84112 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1972) 83 (1): 13–28. https://doi.org/10.1130/0016-7606(1972)83[13:TOTISB]2.0.CO;2 Article history received: 01 Mar 1971 rev-recd: 09 Jul 1971 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation MARC L SBAR, MUAWIA BARAZANGI, JAMES DORMAN, CHRISTOPHER H SCHOLZ, ROBERT B SMITH; Tectonics of the Intermountain Seismic Belt, Western United States: Microearthquake Seismicity and Composite Fault Plane Solutions. GSA Bulletin 1972;; 83 (1): 13–28. doi: https://doi.org/10.1130/0016-7606(1972)83[13:TOTISB]2.0.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 SocietyGSA Bulletin Search Advanced Search Abstract During the summer of 1969, six portable seismographs were operated at 82 sites along the Intermountain Seismic Belt from southwestern Utah to northwestern Montana. This survey followed a well-known seismic belt along the eastern physiographic boundary of the Basin and Range province, and within the middle and northern Rocky Mountains. In general, the 120 microearthquakes located in this study follow the same spatial trend as the macroseismic earthquakes reported by the NOS (formerly USCGS). Most of the micro-earthquakes clustered in time and space along well-known fault zones on which late Tertiary or younger movements have occurred. All of the accurately located hypocenters occurred between the surface and a 20 km depth. Composite fault plane solutions along the Hurricane and Sevier fault zones (southwestern Utah), Tushar and Sevier fault zones (Marysvale area, Utah), and Wasatch and East Cache fault zones in central and northern Utah indicate vertical-motion on steeply dipping fault planes. These motions may be indicative of differential movements between the Basin and Range province and the Colorado Plateau-Rocky Mountains. Composite fault plane solutions (CFPS) in the Caribou Mountains, southeastern Idaho, and Flathead Lake area, northwestern Montana, show normal faulting on less steeply dipping planes and have west-northwest trending extensional axes. Swarm activity was also observed in the above two regions. Between the above two areas of uplift and extension lies a region of complicated geology and seismicity. 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.