Research

Paleoseismology of the Western Nepal Fault System (WNFS)

My research on the Western Nepal Fault System (WNFS) focuses on reconstructing the timing and style of past earthquakes to better understand how upper-plate faults accommodate Himalayan convergence. As a dextral-normal fault system in the hinterland of an oblique convergent margin, the WNFS presents an intriguing tectonic puzzle—it cuts obliquely across the structural grain of the orogen and may link into the underlying Main Himalayan Thrust (MHT). This geometry raises a key question: Can the WNFS rupture co-seismically with the megathrust?

Over the course of three field seasons, our team excavated seven hand-dug trenches across multiple fault strands of the WNFS (red dots on map). Detailed logging, stratigraphic analysis, and radiocarbon dating of these sites provide new insight into the timing, recurrence, and extent of Holocene surface-rupturing earthquakes along the system. Together, these data form one of the first integrated paleoseismic records for the high Himalaya and help clarify the potential for complex, multi-fault rupture scenarios in western Nepal.

Results indicate that the WNFS has ruptured multiple times during the Holocene, recording at least three surface-rupturing earthquakes since ~12 ka. These events demonstrate that the fault system is both active and capable of producing large-magnitude earthquakes within the upper plate. Correlating earthquake age constraints across trench sites, together with evidence from other paleoseismic studies and historical records, indicates that the WNFS likely ruptured system-wide and concurrently with the Main Himalayan Thrust during the 1505 CE Great Himalayan Earthquake.

Collectively, these findings provide the first systematic evidence for repeated surface ruptures across the high Himalaya and reveal that complex, multi-fault ruptures are possible in western Nepal. This work refines our understanding of how oblique convergence is accommodated in the Himalayan orogen and has important implications for regional seismic hazard assessment.

Check out our publication here: https://doi.org/10.1130/GES02880.1

Age-depth plots for each trench, schematically stacked to speculate correlations between paleoseismic sites. Red and yellow PDFs bound earthquake events and small gray PDFs are our radiocarbon age control. The yellow PDFs specifically span a window of time that overlaps with the 1505 Great Himalayan Earthquake.

Some photos from field work in Nepal

Investigating controls of fault damage zone width in the Eastern California shear zone (ECSZ)

My research in the ECSZ investigates the controls on fault damage zones and off-fault deformation (OFD), with a focus on how preexisting crustal weaknesses influence their width and intensity. I specifically examine the role of the Jurassic-aged Independence Dike Swarm, a regionally extensive network of dikes that is likely influencing fault damage zones.

Using fracture intensity transects across fault zones and remote dike mapping in Google Earth and ArcGIS, I assess how dike orientations align with active faults and correlate with patterns of damage and deformation. Although still in the early stages, preliminary results show a clear relationship between dike-rich regions and wider, more fracture-intensive damage zones, suggesting that the Independence Dike Swarm exerts a strong control on fault zone architecture. These results highlight the role of structural inheritance in shaping fault evolution within the ECSZ.

Check out my lab mate's paper on restraining bends in ECSZ: https://doi.org/10.1029/2023TC008148

Older Research Projects

Paleoseismology of the Thousand Springs Fault, Summer Lake, OR, Northwestern Basin and Range

My masters project was a trenching investigation of a previously undocumented fault in Summer Lake with Dr. Anne Egger at Central Washington University. The lake sediments host >200,000 years of tephra deposition, providing excellent age control within our trenches. This study revealed data suggestive of synchronous fault behavior across the basin, resulting in the claim to study low-strain-rate faults as system of faults and not single sources.
Check out our publication here: https://doi.org/10.1785/0120230283

Paleoseismology of Sinistral-Slip Fault System, Focusing on the Mae Chan Fault, on the Shan Plateau, SE Asia.

I was lucky enough to participate in undergrad research with Dr. Ray Weldon at University of Oregon. We went to Thailand in February 2017 and trenched multiple faults as a part of a Earth Observatory of Singapore funded cross border collaboration for paleoseismology. My work focused on a trench dug across the Mae Chan fault in northern Thailand, which revealed at least one large earthquake on the fault.