SCEC Award Number 25192 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Detailed VP and VS Model, and Seismicity Catalog of the Mina Deflection Region of the Central Walker Lane from a Rapid Nodal Deployment
Investigator(s)
Name Organization
Patricia Persaud University of Arizona
SCEC Milestones A1-3, A2-3, A3-2, D1-1 SCEC Groups PBS, Seismology, CEM
Report Due Date 03/15/2026 Date Report Submitted 03/28/2026
Project Abstract
 The 2020 Mw 6.5 Monte Cristo Range earthquake occurred in the California-Nevada border region. The earthquake occurred on a previously unmapped fault, in the Central Walker Lane. The Walker Lane and Eastern California Shear Zone can be considered a natural laboratory outside the most populated regions of California for SCEC to consider issues of seismicity and fault mechanics (e.g., Wesnousky, 2024). The USGS rapidly deployed 60 three-component nodal seismic instruments to monitor the aftershock sequence of the event and data were recorded for one month. Using EQTransformer and our hybrid U-Net model for automatic event detection and phase picking, we will first produce and refine a catalog of the aftershocks. Detections occurring on at least 10 stations will be classified as events. Our preliminary results show that over 19,400 events were detected in the 1-month period. Compared to the Ruhl et al. catalog of 16,714 events from eight stations that recorded for 3.5 months, our initial catalog contains 16% more events with increased ray path density across the aftershock area. In the proposed study, we will refine our preliminary work to produce a high-fidelity earthquake catalog and 3D P-wave and S-wave travel-time tomographic models from the phase picks that will be interpreted along with receiver functions. This will better capture velocity contrasts, allowing us to image the shallow crust and examine the structural complexity of the aftershock region. The velocity models in the CA-NV border region will also be made available for inclusion in statewide Earth models.
Intellectual Merit Our study contributes to the SCEC mission of analyzing data from field observations and developing subsurface multi-scale models for improving understanding of seismic hazards. We’ve developed the first multi-scale 3D models with quantified uncertainties, that image the geometry and depth of six sedimentary basins in the Central Walker Lane. Our models resolve rheological transitions within the crust that directly impact earthquake nucleation. They provide insights into deformation along recent transtensional fault zones thereby contributing to our understanding of immature fault systems. Our multi-scale velocity models, density model and earthquake catalog will accompany the peer review publication.
Broader Impacts This project involved a PhD student and a postdoctoral researcher. A new method was developed in this study that produces a full suite of multiscale Earth models (VP, VS, VP/VS, density) with uncertainties for the Central Walker Lane. The models draw on diverse datasets (seismic and gravity) and a newly created deep-learning earthquake catalog produced from nodal array recordings. This approach can be readily applied to other SCEC focus areas to help improve ground motion predictions. The results from this research have been used in presentations and lectures given by the PI and other project participants.
Project Participants Joses Omojola, Patricia Persaud, Benjamin Sadler
Exemplary Figure Figure 2. 3D perspective view from the southeast of the VP = 6.4 km/s iso-velocity surface obtained from our large-scale VP model in the CA-NV border region. The iso-velocity surface highlights major mountain ranges across the study area. The pink dashed rectangle marks the location of our high-resolution model covering the Central Walker Lane (CWL) region including the aftershock region of the 2020 Mw 6.5 Monte Cristo Range earthquake.
Linked Publications

Add missing publication or edit citation shown. Enter the SCEC project ID to link publication.