Optimal Fault Orientations within Oklahoma

Research Article| September 01, 2013 Optimal Fault Orientations within Oklahoma Austin A. Holland Austin A. Holland Oklahoma Geological Survey, 100 E. Boyd Street, Room N131, Norman, Oklahoma 73019‐0628 U.S.A.austin.holland@ou.edu Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2013) 84 (5): 876–890. https://doi.org/10.1785/0220120153 Article history first online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Austin A. Holland; Optimal Fault Orientations within Oklahoma. Seismological Research Letters 2013;; 84 (5): 876–890. doi: https://doi.org/10.1785/0220120153 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 SocietySeismological Research Letters Search Advanced Search ABSTRACT One hundred and fifty‐two focal mechanisms determined for earthquakes occurring in Oklahoma for about 30 months were used to determine the optimally oriented fault orientations within the region. A large number of these focal mechanisms were concentrated in central Oklahoma and can be associated with the ongoing Jones earthquake swarm and the 5 November 2011 Prague earthquake sequence. In addition, there were focal mechanisms determined throughout Oklahoma while the Earthscope Transportable Array was located in the region. Focal mechanisms used in this paper include Regional Moment Tensor solutions when available and first‐motion focal mechanisms. The probability density functions (PDF) with a 10° bin were calculated for both possible nodal planes associated with the observed focal mechanisms. Focal mechanisms within the Jones swarm are clearly different than those from the rest of Oklahoma, and appear to be primarily controlled by the orientation of existing natural fracture orientations. The results clearly demonstrate that strike‐slip motion on steeply dipping faults dominates the focal mechanism distribution. Fault strike was restricted to the range of 0° to 180°. The optimal fault strike orientation ranges between 40°–60° and 130°–150° and represent fault orientations most likely to have an earthquake. From the PDF it is possible to define orientations of moderate likelihood of having earthquakes with strikes in the range of 20°–40° and 110°–130° with all other orientations of fault strike having a low likelihood. These results may help oil and gas operators in Oklahoma modify operations to reduce the likelihood of triggered seismicity. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.