Cataloging the Date of Last Event (DOLE) Across the Western U.S.
Description:
The elapsed time since the most recent earthquake (the open interval) on a given fault is a primary constraint required for time-dependent seismic hazard analyses. Additionally, the timing of the most recent earthquake and paleoseismic chronologies are key targets in earthquake geology research. The high density of paleoseismic studies in California and along the Wasatch front, along with historical earthquakes, have focused attention of prior time-dependent probabilistic seismic hazard analyses (PSHA) in these regions. These hazard models generally yield a relative decrease in the probability of moderate-to-large ruptures on faults with recent ruptures (e.g., 1999 Hector Mine rupture, CA), and a relative increase of rupture rates on faults that may be late in the seismic cycle (e.g., Brigham City section of Wasatch fault, UT). To enable the proposed expansion of time-dependent PSHA analysis across the western U.S., we augmented the western U.S. NSHM fault sections database with paleoseismic and historic date of last event (DOLE) data. We added ~70 sites to the ~60 existing sites previously compiled within California and along the Wasatch fault. Additionally, we added ~10 historical rupture extents to the compilation. This compilation includes paleoseismic investigations as points and expands those site observations onto existing NSHM fault sub-section geometries as lines. Translating site observations to rupture extents remains challenging, and we take a minimum-length approach as was done in previous time-dependent PSHA in California. On faults without a paleoseismic or historic event, we use a regionalized onset of historical settlement to demarcate the minimum time since a large earthquake has occurred. In addition to implementation in time-dependent PSHA, we hope this compilation will be useful to the earthquake geology community as we develop models of earthquake occurrence through space and time, better constrain geologic slip rates, and plan future paleoseismic trench investigations, among other applications.
Session: From Faults to Fjords: Earthquake Evidence in Terrestrial and Subaqueous Environments [Poster Session]
Type: Poster
Date: 5/1/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Alexandra
Student Presenter: No
Invited Presentation:
Authors
Alexandra Hatem Presenting Author Corresponding Author ahatem@usgs.gov U.S. Geological Survey |
Richard Briggs rbriggs@usgs.gov U.S. Geological Survey |
Madeleine Tan mtan@usgs.gov U.S. Geological Survey |
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Cataloging the Date of Last Event (DOLE) Across the Western U.S.
Session
From Faults to Fjords: Earthquake Evidence in Terrestrial and Subaqueous Environments