Earthquake Magnitude-Frequency Distributions in the Northern Caribbean Plate Boundary Using Combinatorial Optimization
Description:
On-fault earthquake magnitude-frequency distributions are calculated for northern Caribbean faults using estimates of fault slip and regional seismicity parameters. Integer programming, a combinatorial optimization method, is used to determine the optimal spatial arrangement of earthquakes sampled from a truncated Gutenberg-Richter distribution that minimizes the global misfit in slip rates on a complex fault system. Slip rates and their uncertainty on major faults are derived from a previously published GPS block model for the region, with fault traces determined from offshore geophysical mapping and previously published onshore studies. The optimal spatial arrangement of the sampled earthquakes on these faults is compared with the 500-year history of earthquake observations. Rupture segmentation of the subduction interface along the Hispaniola-Puerto Rico Trench (PRT) fault and the degree of seismic coupling on the PRT fault appear to exert the primary control over this spatial arrangement. Introducing a rupture barrier for the Hispaniola-PRT fault northwest of Mona Passage, based on geophysical and seismicity observations, and assigning a low slip rate of 2 mm/yr on the PRT fault are most consistent with historical earthquakes in the region. The addition of low slip-rate secondary faults as well as segmentation of the Hispaniola and Septentrional strike-slip fault improves the consistency with historical seismicity. The modeling indicates that varying the slip rate on the PRT fault and different segmentation scenarios result in significant changes to the optimal magnitude distribution on faults farther away, such as Enriquillo and Septentrional. Maximum magnitudes on plate boundary faults from the forecasted distributions are less than the physical maximum magnitude calculated from the entire area of the fault, calling into question the feasibility of an M9 on the PRT.
Session: Active Faults in the Caribbean and Central America
Type: Oral
Date: 4/20/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Uri S. ten Brink
Student Presenter: No
Invited Presentation: Yes
Authors
Eric Geist egeist@usgs.gov U.S. Geological Survey |
Uri ten Brink Presenting Author Corresponding Author utenbrink@usgs.gov U.S. Geological Survey |
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Earthquake Magnitude-Frequency Distributions in the Northern Caribbean Plate Boundary Using Combinatorial Optimization
Category
Active Faults in the Caribbean and Central America