Persaud Lab
This page includes brief descriptions of some of our research studies. Links to our other research pages:
BASIN (Basin Amplification Seismic INvestigation)
BIMA (Bangladesh-India-Myanmar Array)
ISLA - Seismic Monitoring in Louisiana
Myanmar Universities Seismic Experiment
Salton Trough
FURTHER - The role of FlUids in the pReparaTory pHase of EaRthquakes in Southern Apennines (collaboration)
(INGV project, PI - F. Di Luccio) The overarching goal of this project is to investigate the role of fluids in the preparatory phase of earthquakes in the Southern Apennines, Italy. The group aims to study the pathway of fluids from the source to the upper crust where major earthquakes occur, using a cross-disciplinary approach that includes seismological, geochemical, geodetic and geospace data. The interplay of fluids, shallow and deep-seated active structures and seismicity will be explored at the local and regional scales, including imaging the seismic structure beneath the Southern Apennines, but also at the larger scale revealing signals, if any, that can be interpreted as precursors of large earthquakes. We are contributing to the structural imaging by using receiver functions computed from recordings at broadband stations in the region. 
The Aeolian Islands consist of a 150-km long active volcanic arc and are located between the Southern Tyrrhenian Sea backarc basin and the Calabrian Arc. As part of a collaborative project between Istituto Nazionale di Geofisica e Vulcanologia (INGV) Rome and LSU, we will study the seismic structure of the active hydrothermal system beneath Lipari Island using a nodal array and determine a detailed velocity model that will be useful for assessing the seismic hazard. A recent study has shown that a decrease in fluid discharge may reflect pressurization at depth that potentially precedes hydrothermal explosions. The object of this study is to further our understanding of these processes by providing detailed images of the subsurface structure of Lipari Island.
The target area in our study is outlined in red in the map on the left. Synthetic tests show that a (semi) circular wave-front geometry of the array will provide a good spatial resolution for the ~1 km-radius array at frequencies between 0.1 and 5 Hz.
More information on our Nodal array deployed in October 2018 can be found here and in the Eos article, Seismic Sensors Probe Lipari’s Underground Plumbing.
This project is a new effort to update the SCEC Crustal Stress Model for Southern California with direct stress measurements from borehole breakouts. We have a growing dataset of 82 wells with 4-, 6- and 8-arm caliper data from oil fields in Los Angeles near the Newport-Inglewood Fault, and 32 wells with oriented caliper and sonic logs in the offshore Santa Barbara Channel region. We have obtained the data from logging companies, well operators, and oil companies in the L.A. Basin. The results from this work are an important complement to constraints from seismicity, as borehole data provide a finer spatial resolution at shallower depths. Our preliminary results show similar stress directions to previous work in this region, but also significant variation particularly with depth, which can be more closely studied with the high spatial density of this new dataset.
We used Rayleigh wave group velocity dispersion measurements from local and regional earthquakes to interpret the lithospheric structure in the Gulf of California. We have identified remnants of the Farallon slab beneath the Baja peninsula, a possible asthenospheric window beneath northern Baja, and terrane boundaries in Sonora. New findings include large-scale regions of asthenospheric upwelling associated with the rift axis, as well as evidence of lower crustal flow from the margins of the Gulf towards the rift axis. For more details see Di Luccio et al. (2014) and Persaud et al. (2015).
Our aim is to understand why the Northern Gulf of California, a region of transition from continental rifting to seafloor spreading does not look like a typical midocean ridge-transform boundary. We use geodynamic models to help answer some of the overarching questions; namely, what mechanism produced the multiple faults, does the large pull-apart structure only affect soft sediments of the upper crust or does this also reflect the deeper structure, and how does the obliquity influence the style of deformation?
We investigate how factors such as crustal composition, thickness, obliquity and driving mechanism affect the style of deformation using 2.5-D dynamic models, which allow for the spontaneous formation of localized normal and strike-slip faults. These numerical experiments result in distributed deformation in all cases with linear basal drag. This demonstrates that the style of deformation depends not only on the rift obliquity but also on the strike-slip boundary conditions, an important point for edge-driven approaches to understanding the evolution of geologic structures. See Persaud et al. (2016) for numerical model results.
We study the seismic structure of the Calabrian subduction zone beneath the Tyrrhenian Sea in the western Mediterranean using events deeper than 200 km that were recorded by the Italian seismic network managed by Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Italy. Our data set also includes recordings at ocean bottom seismometers and hydrophones. We model the waveforms using the 2-D staggered grid Finite Difference method on graphics processing units developed by Li et al. (Geophys. J. Int., 2014). Accurate analysis of the source-to-receiver raypaths reveals significant differences for paths through the slab compared to other paths. P-wave complexity, converted phases and high-frequency content are some of the features we observed for selected events.