| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | November 19, 2015 |
| Latest Amendment Date: | November 27, 2018 |
| Award Number: | 1602764 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Steven Whitmeyer
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | December 1, 2015 |
| End Date: | May 31, 2019 (Estimated) |
| Total Intended Award Amount: | $32,924.00 |
| Total Awarded Amount to Date: | $32,924.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
115 JOHN WILDER TOWER MEMPHIS TN US 38152-0001 (901)678-3251 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
103 Earthquake Center 3 Memphis TN US 38152-3370 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | DEEP EARTH PROCESSES SECTION |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Scientists from the University of Memphis in collaboration with scientists from the Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales will install 4 new continuous GPS stations and perform post-earthquake survey GPS measurements on 35 benchmarks in San Juan, Argentina. The measurements will be used to determine the mid-field co- seismic and post-seismic deformations of the September 16, 2015 Mw 8.3, megathrust earthquake offshore Illapel, Chile. These measurements, which capture the deformation field 100-400 km to the east of the earthquake, will complement similar activities in the immediate epicentral area in Chile from the Chilean Seismic Network. The mid-field to far-field signals are small, but significant as they are both poorly modeled and poorly understood in comparison to the much larger near-field signals. The mid- to far-field signals sample the response of the South America plate lithospheric stress guide, and the viscoelastic mantle wedge under the Andes in the west, and South America cratonic upper mantle to the east.
The South America-Nazca plate boundary is unique as it is the only major convergent boundary where an almost complete aerial sampling of megathrust earthquake cycle deformation, from near- to far-field, can be observed in the upper plate side of a subduction system. Megathrust earthquakes along the South America-Nazca plate boundary produce large, rapid co-seismic deformations stretching across the whole continent. They also produce plate-wide post-seismic deformations that are initially faster than the inter-seismic deformations and can even surpass the co-seismic offset. These rapidly changing deformations may play an important role in tectonics by temporally concentrating aseismic deformation or triggering earthquakes. These signals decay with time, thus a rapid GPS deployment is necessary to capture the deformation signal before the signals decrease below the detection level. The proposed activity advances desired societal outcomes by providing data that would aid in determining regions of aftershocks that could be used in hazard mitigation efforts and would contribute to the understanding of earthquake hazard in the region. The project also contributes to enhanced infrastructure for research through the expansion of a GPS network and to adjustment of national geodetic reference frames.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This project was an NSF RAPID award to record ephemeral ground movements in Argentina during and following the 2015, magnitude 8.3, Illapel earthquake on the South America-Nazca plate boundary in neighboring Chile. In the case of earthquakes, RAPID awards are used to collect important “co-seismic” and “post-seismic” data associated with the earthquake. The co-seismic signals are those associated with the earthquake and occur over periods of 10’s of seconds. The post-seismic signals start immediately after the earthquake and decay over minutes to years. The post-seismic signals include the aftershocks and ground movements that follow large earthquakes. Aftershocks are a well-known phenomenon and generally limited to the immediate region of the earthquake. The co-seismic and post-seismic ground movements are a less well-known phenomena that are important for determining physical properties of the earth’s crust and mantle, understanding the earthquake cycle, and can be large enough to affect standard survey engineering measurements. These earthquake generated movements include a quick jump in position associated with the earthquake - the “co-seismic” jump, which occurs over time periods of 10’s of seconds, and a continuing smaller and slower post-seismic movement that decays over a period of years for great earthquakes. While the ground movements are largest in the immediate region of the earthquake, both the co- and post-seismic movements span a much wider region in space than the immediate epicentral area. The ground movements outside the immediate earthquake region of the 2015 Illapel earthquake, which is limited to the Chilean coast, are the focus of the data collection effort supported by this RAPID award and the region of interest extends from the Argentine-Chilean border into the middle of Argentina and the signals will extend over a time period of a decade or more. The RAPID award measured the movements of earth’s crust through the installation of 6 continuous GPS or GNSS stations in the latitude range of the Illapel earthquake in the western part of the San Juan Province of Argentina. The RAPID award filled a hole in GPS coverage between the GPS networks in Chile to the west and the Argentine National Geodetic Network (RAMSAC) to the east. This gap was in the region with the largest and fastest signal from the Illapel earthquake in Argentina. The RAPID award is principally to capture the ephemeral data associated with the earthquake and does not contain support for data analysis. The GPS data collected during the 4 years of the project is openly available at the UNAVCO data archive.
To date, working with the Argentine National Geodetic Survey, the data is being used to update the Argentine National Geodetic Reference frame for the effects of both the co-seismic and post-seismic motions of the Illapel earthquake using a technique described in an abstract presented at the Fall 2019 meeting of the American Geophysical Union in San Francisco. The technique was implemented in Argentina by a graduate student at the National University of San Juan, Argentina, who will be starting her Ph.D. at OSU in the fall of 2020. We will be adding this data to that from the Chilean and Argentine networks to the east and west to improve geodynamic and earthquake cycle models for this region.
The O&M campaigns to download data and service the stations were performed by Argentine Engineer and technician collaborators from the Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA ), CONICET, Mendoza, Argentina, and the Instituto Nacional de Prevención Sísmica, San Jaun, Argentina, that we trained. While the NSF RAPID award has ended, in collaboration with our Argentine collaborators, several of the stations will be upgraded to have real-time communications and participate in the Argentine National Geodetic Network (RAMSAC) and all the stations will continue operating and providing open data.
Last Modified: 03/19/2020
Modified by: Robert Smalley
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