Earthquake Interaction, Fault Structure, and Source Properties of a Small Sequence in 2017 near Truckee, California

Research Article| August 14, 2018 Earthquake Interaction, Fault Structure, and Source Properties of a Small Sequence in 2017 near Truckee, California Rachel L. Hatch; Rachel L. Hatch aNevada Seismological Laboratory, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89503, rhatch@nevada.unr.eduken@unr.edu Search for other works by this author on: GSW Google Scholar Rachel E. Abercrombie; Rachel E. Abercrombie bDepartment of Earth and Environment, Boston University, 685 Commonwealth Avenue, Boston, Massachusetts 02215, rea@bu.edudAlso at Nevada Seismological Laboratory, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89503. Search for other works by this author on: GSW Google Scholar Christine J. Ruhl; Christine J. Ruhl cUC Berkeley Seismological Laboratory, University of California, Berkeley, McCone Hall, 215 Haviland Path #4760, Berkeley, California 94720, cruhl@berkeley.edu Search for other works by this author on: GSW Google Scholar Kenneth D. Smith Kenneth D. Smith aNevada Seismological Laboratory, University of Nevada, Reno, 1664 North Virginia Street, Reno, Nevada 89503, rhatch@nevada.unr.eduken@unr.edu Search for other works by this author on: GSW Google Scholar Bulletin of the Seismological Society of America (2018) 108 (5A): 2580–2593. https://doi.org/10.1785/0120180089 Article history first online: 14 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Rachel L. Hatch, Rachel E. Abercrombie, Christine J. Ruhl, Kenneth D. Smith; Earthquake Interaction, Fault Structure, and Source Properties of a Small Sequence in 2017 near Truckee, California. Bulletin of the Seismological Society of America 2018;; 108 (5A): 2580–2593. doi: https://doi.org/10.1785/0120180089 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 SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract We use relocation and source parameter analysis, including stress drop and directivity, to investigate fault structure and earthquake interaction of small‐magnitude earthquakes within a sequence in the Walker Lane tectonic region. Two high‐angle, left‐lateral strike‐slip earthquakes (⁠Mw 3.65 foreshock and Mw 3.85 mainshock), occurred 7 min apart, ∼20 km north of Truckee, California, on 27 June 2017. Both events were felt over a wide area in northeastern California and northwestern Nevada and happened nearby Holocene fault zones including the Polaris, Mohawk Valley, and Dog Valley Quaternary fault zones that pose a significant hazard to the populated regions in the area. We use waveform cross correlation to relocate the earthquakes and empirical Green's‐function methods to estimate the source parameters of all ML>2 events. Also, we estimate the rupture directivity for the two largest events. We relocate 50 out of 52 earthquakes within the sequence, with an average relative error of <30 m⁠. The events define a single structure between 5 and 6 km depth, trending ∼N45°E and dipping ∼70°–80° to the northwest. The distribution of relocations matches the northeast‐striking plane from both the moment tensor solutions and computed first‐motion focal mechanisms, indicating sinistral strike‐slip motion on a previously unmapped fault. We observe average stress drops of ∼5 MPa using P and S waves and spatial variation related to the rupture areas of the foreshock and mainshock. We are able to detect components of directivity toward the northeast for the foreshock (⁠Mw 3.65) and directivity toward the southwest for the mainshock (⁠Mw 3.85), both aligning with the fault plane. This analysis illustrates details in source properties and rupture propagation that can be derived with high‐precision event locations within dense regional networks and provides more data and a better understanding as it relates to potential seismic hazard. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.