Surface Structure of the Punta Montalva Fault in Southwestern Puerto Rico Using High-Resolution Digital Elevation Models
Description:
The Punta Montalva Fault is an active fault that slipped during the 2019-2021 Puerto Rico seismic sequence. The fault cuts Miocene limestone and contains surface features that suggest left-lateral displacement. Previous work suggested that the fault connects with the North Boquerón Bay Fault for a length of 33 km and poses a large seismic hazard. However, not much is known about the structure, segmentation, and spatial extent of the fault as it is obscured under thick vegetation. This study used high-resolution topographic and bathymetric lidar data to map the surface structure, segmentation, and spatial extent of the fault. The results would allow us to further comprehend the seismic potential of the fault.
High-resolution mapping revealed that the Punta Montalva Fault comprises three main fault segments on land and three fault scarps on the seafloor to the SE. No surficial evidence suggests the Punta Montalva Fault extends further NW into La Parguera. The DEM revealed that the fault cuts a shallowly dipping sedimentary sequence of the Ponce Limestone that has karst topography in places. On land, the fault is conspicuous where it forms scarps, drags and cuts sedimentary layers, and forms a duplex structure with a predominantly left-lateral offset. A left-lateral offset of an intermittent stream has been refined to 133.6 m. The fault scarps along a marine shelf strike E-W and show a maximum normal offset of 4.8 m. Another fault scarp in the seafloor strikes NW-SE and displays a left-lateral offset of 98.3 m. The total length of the fault segments is ~ 2.67 km long. The surface segmentation suggests that the fault would have a lower seismic hazard than if it were continuous and connected to the North Boquerón Bay Fault. However, subsurface imaging is needed to check whether the surface segmentation and extent are characteristic of the subsurface structure of the fault. Strike-slip and normal offset suggest that the area is being deformed by transtentional deformation, which supports seismic analyses and tectonic models.
Session: Active Faults in the Caribbean and Central America [Poster]
Type: Poster
Date: 4/20/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Daniel A. Laó-Dávila
Student Presenter: No
Invited Presentation:
Authors
Lauren Weilert lauren.weilert@okstate.edu Oklahoma State University |
Daniel Laó-Dávila Presenting Author Corresponding Author daniel.lao_davila@okstate.edu Oklahoma State University |
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Surface Structure of the Punta Montalva Fault in Southwestern Puerto Rico Using High-Resolution Digital Elevation Models
Category
Active Faults in the Caribbean and Central America