Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock
Abstract The M6.4 mainshock of the southwestern Puerto Rico seismic sequence on 7 January 2020, was one of the most impactful modern earthquakes in the northeastern Caribbean. Due to its offshore location and complex aftershock distribution, its source kinematics remain poorly constrained. This acti...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2025-04-01
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| Series: | Geophysical Research Letters |
| Online Access: | https://doi.org/10.1029/2024GL109740 |
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| author | M. M. Solares‐Colón D. E. Goldberg D. Melgar E. A. Vanacore V. J. Sahakian W. L. Yeck F. Hernández A. M. López‐Venegas |
| author_facet | M. M. Solares‐Colón D. E. Goldberg D. Melgar E. A. Vanacore V. J. Sahakian W. L. Yeck F. Hernández A. M. López‐Venegas |
| author_sort | M. M. Solares‐Colón |
| collection | DOAJ |
| description | Abstract The M6.4 mainshock of the southwestern Puerto Rico seismic sequence on 7 January 2020, was one of the most impactful modern earthquakes in the northeastern Caribbean. Due to its offshore location and complex aftershock distribution, its source kinematics remain poorly constrained. This active sequence illuminated a complex set of previously unrecognized structures that indicate multiple causative faults may have slipped during its rupture. Here, we utilize seismic and geodetic observations to enhance model resolution, estimate the finite slip of the mainshock, and test a multi‐segment, geologically realistic fault geometry. Our refined model finds a lower rupture velocity and longer rise times than typical for an event of this magnitude. This indicates a slow‐evolving rupture process that resembles characteristics of a tsunami earthquake. Although this normal/strike‐slip faulting event was not tsunamigenic, these qualities, if pervasive for this region, have important implications for future seismic monitoring and hazards in southwestern Puerto Rico. |
| format | Article |
| id | doaj-art-fe0063cc38a44e48baaa6b52fb6d75d9 |
| institution | Kabale University |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-fe0063cc38a44e48baaa6b52fb6d75d92025-08-20T03:44:25ZengWileyGeophysical Research Letters0094-82761944-80072025-04-01528n/an/a10.1029/2024GL109740Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico MainshockM. M. Solares‐Colón0D. E. Goldberg1D. Melgar2E. A. Vanacore3V. J. Sahakian4W. L. Yeck5F. Hernández6A. M. López‐Venegas7U.S. Geological Survey Geologic Hazards Science Center Golden CO USAU.S. Geological Survey Geologic Hazards Science Center Golden CO USADepartment of Earth Sciences University of Oregon Eugene OR USADepartment of Geology Puerto Rico Seismic Network University of Puerto Rico at Mayagüez Mayagüez PR USADepartment of Earth Sciences University of Oregon Eugene OR USAU.S. Geological Survey Geologic Hazards Science Center Golden CO USADepartment of Civil Engineer Strong Motion Program University of Puerto Rico at Mayagüez Mayagüez PR USADepartment of Geology Puerto Rico Seismic Network University of Puerto Rico at Mayagüez Mayagüez PR USAAbstract The M6.4 mainshock of the southwestern Puerto Rico seismic sequence on 7 January 2020, was one of the most impactful modern earthquakes in the northeastern Caribbean. Due to its offshore location and complex aftershock distribution, its source kinematics remain poorly constrained. This active sequence illuminated a complex set of previously unrecognized structures that indicate multiple causative faults may have slipped during its rupture. Here, we utilize seismic and geodetic observations to enhance model resolution, estimate the finite slip of the mainshock, and test a multi‐segment, geologically realistic fault geometry. Our refined model finds a lower rupture velocity and longer rise times than typical for an event of this magnitude. This indicates a slow‐evolving rupture process that resembles characteristics of a tsunami earthquake. Although this normal/strike‐slip faulting event was not tsunamigenic, these qualities, if pervasive for this region, have important implications for future seismic monitoring and hazards in southwestern Puerto Rico.https://doi.org/10.1029/2024GL109740 |
| spellingShingle | M. M. Solares‐Colón D. E. Goldberg D. Melgar E. A. Vanacore V. J. Sahakian W. L. Yeck F. Hernández A. M. López‐Venegas Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock Geophysical Research Letters |
| title | Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock |
| title_full | Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock |
| title_fullStr | Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock |
| title_full_unstemmed | Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock |
| title_short | Slow Rupture, Long Rise Times, and Multi‐Fault Geometry: The 2020 M6.4 Southwestern Puerto Rico Mainshock |
| title_sort | slow rupture long rise times and multi fault geometry the 2020 m6 4 southwestern puerto rico mainshock |
| url | https://doi.org/10.1029/2024GL109740 |
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