Dr. Patricia Persaud

The Node Lab

Seismological Research in the Node Lab at LSU
Charging and Harvesting rack with nodes. Jan 21, 2017

Welcome to our research "lab" that houses 50 modern, self-contained seismometers ("nodes") from FairfieldNodal.

A seismometer is a very sensitive instrument that is placed in the ground and detects very small movements resulting from the passage of seismic waves. With these recordings we are able to image beneath the Earth's surface, study earthquake sources, and monitor subtle changes in the subsurface such as aquifer recharge that are usually difficult to detect.

July 2018 - Scouting sites for the nodes on Lipari (Aeolian Islands)
Map showing the planned locations of the 50 nodes that will be deployed on Lipari Island in October 2018.
Field location of one of the nodes (Node 36) on the southwest side of the island.
Perspective view of the southwest side of Lipari island.
Another node location (Node 38) on the southwest side of the island.

In mid-July 2018, our INGV* team comprised of Francesca Di Luccio, Luigi Cucci and Alessandra Esposito scouted the locations of our instruments on Lipari Island. We will deploy the nodes in early October 2018 and record ambient noise and local seismicity over a time period of 35 days. The array will have a roughly semicircular geometry in and around the hydrothermal area, with the final configuration determined strictly by the topography. Seismic data will be merged with the surface lithology, faults and fractures, and volcanic structures mapped during the seismic acquisition, and interpreted along with measurements of the CO2 gas flux from the study area. The combined analysis of simultaneous measurements of CO2 gas release and seismic properties will provide information on the dynamics of fluid ascent and pathways. Results from this study will improve our understanding of the fluid dynamics at shallow depth and the unrest episodes in active volcanic and hydrothermal areas.

More information on the project can be found here.

*National Institute of Geophysics and Volcanology, Rome, Italy

July 2018 - Northern Los Angeles - PHASE II BASIN Seismic Experiments
Persaud and a Caltech undergradute student deploying and marking the location of a node in the front yard of a Los Angeles resident.
Node locations are documented with a "Node-pointing" photo.
2018 Deployment Team.

We were back in the Los Angeles area this summer to add three new seismic profiles across the San Bernardino basin.

Our 2018 deployment team (photo in the lower left) included volunteers from the Jet Propulsion Lab, Cal Poly Pomona, the USGS, USC, LSU and Caltech.

Read Phys.org news article about our study at this link and our new SRL article.

Jun 2017 - Northern Los Angeles BASIN Seismic Experiments
Local Event 2017/02/27 M=2.7

(Click on image for a larger view) Z-component recording of a local earthquake, M 2.7 in the San Gabriel basin along Line 2 in the map below.

The vertical component of a local earthquake (M 2.7) recorded along Line 2 of our seismic experiment. The map below shows the locations of the three profiles in our final deployment. We deployed Lines 1 and 2 across the San Gabriel basin, and Line 3 across the Chino basin. The northwestern end of Line 2 is located near the Rose Bowl in Pasadena, CA.

Jun 2017 - Northern Los Angeles BASIN Seismic Experiments
Teleseismic Event Bolivia 2017/02/21 M=6.5 Depth=596 km

Map showing the final BASIN deployment, a total of 199 nodes from LSU (Line 2), University of Utah (Line 3) and PASSCAL (Line 1).

In one month, we were able to record at least two clear teleseismic earthquakes that are useful for producing high-resolution receiver functions. The vertical and east components of one of these teleseismic events (M 6.5) are shown in the two figures below. More data from our experiment can be viewed at Rob Clayton's page.

(Click on image for a larger view) The E-component of the M 6.5 earthquake shown on the left.
(Click on image for a larger view) Teleseismic earthquake (M 6.5) recorded by the nodes along Line 2 in the map above.
LSU student, Phoenix Harris pointing to a Line 1 node that was deployed in the frontyard of a Los Angeles resident.

Apr 2017 - Successful first deployment
Poster presented at LSU's Discover Day, April 4, 2017.

The nodes are back from their San Gabriel basin deployment. Our group deployed a total of 199 of these small, compact, cable-free seismic instruments in the San Gabriel basin, Southern California with a spacing of ~300 m. 50 nodes were from LSU, 60 from the PASSCAL Instrument Center, and 89 from the University of Utah. The nodes were deployed in an urban environment - in people's backyards, in parks, at the sides of roads and in a golf course. In five teams of 12 people total, LSU's 50 nodes were deployed in about 3 hours.

LSU Geology undergrad, Gus Bates (left) and Rob Clayton from Caltech (right) deploying a PASSCAL node on a golf course. Golf cart in the background was suitable node transportation.

While Arlen worked on dowloading the data and recharging the nodes, Jessica presented our work at LSU Discover Day. See the larger poster here.
We have started to select recordings of teleseismic earthquakes for our receiver function computations. Our objective is to identify the basement contact and basin shape.

Feb 2017 - San Gabriel Basin, Southern California

We are excited about our first deployment of the nodes, which will be in the San Gabriel basin in the Los Angeles metropolitan area as part of a collaborative project. This is preliminary work, and will be followed by subsequent deployments. The group's overall objective is to investigate the amplification of ground motion from a potential earthquake rupture on the southern San Andreas Fault. Our instruments will be deployed for 35 days, and will continuously record earthquakes and ambient noise (video link).

Feb 19, 2017 - G&G students in the field deploying seismometers near the San Andreas Fault, Southern California - Twitter Link.

Map of the Los Angeles area showing the active faults (red lines). LSU's nodes will be deployed along the green line on the west. The northern end of the line is near the Rose Bowl. Jan 21, 2017.
The nodes snug in ther carry packs. Jan 21, 2017.