| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | March 25, 2015 |
| Latest Amendment Date: | September 28, 2023 |
| Award Number: | 1459095 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Gail Christeson
gchriste@nsf.gov (703)292-2952 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | April 1, 2015 |
| End Date: | March 31, 2024 (Estimated) |
| Total Intended Award Amount: | $640,766.00 |
| Total Awarded Amount to Date: | $640,768.00 |
| Funds Obligated to Date: |
FY 2018 = $298,710.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
266 WOODS HOLE RD WOODS HOLE MA US 02543-1535 (508)289-3542 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
183 Oyster Pond Rd Woods Hole MA US 02543-1041 |
| 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): | Marine Geology and Geophysics |
| Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT 01001516DB NSF RESEARCH & RELATED ACTIVIT |
| 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
The last ten years has seen many magnitude 8-9 subduction zone megathrust earthquakes, several of which generated remarkably destructive tsunami. A majority of fault slip during such events occurs offshore underneath the continental shelf of the overriding plate. Limitations in the state of knowledge before these great earthquakes, and documentation of their rupture process, is a direct result of the lack of offshore seismic and geodetic instrumentation above the fault rupture zones. This study adds to an international effort that will initiate installation of seafloor instrumentation on the Iquique segment of the Nazca-South American plate boundary, on which a strong to devastating (Mw >8.5) earthquake is expected to occur. Installing instrumentation now will allow monitoring of deformation in the terminal stage of a seismic cycle leading up to a great earthquake. The region is unique in that predicted likelihood of its readiness for a major quake appears to be well-founded.
A recent M8.1 earthquake just to the north of the study area demonstrates that geodetic coupling models were correct that this segment of the Nazca-South America plate boundary has been locked and built up considerable strain that will continue to be released seismically. A number of mechanical and hydrological properties control whether a given large subduction earthquake will involve high-hazard, shallow slip near the trench or not. One factor that can be quantified in a short-term study is the ongoing deformation of the forearc near the trench, which can be related through numerical models to the locking (versus slowly, aseismically slipping) status of the underlying fault. The onshore/offshore seismic and geodetic observatory to be installed in the Iquique segment through a Chilean-German-US collaboration has potential to be the first interseismic-coseismic-post-seismic dataset for a M>8 earthquake with instrumentation spanning all the way from the trench through the locked zone. The US component of the study will deploy 9 seafloor acoustic ranging instruments along a 15 km transect across the forearc slope for 3 years. Stations will be sited on the basis of new AUV seafloor mapping and will be nested within a ~100 km shelf-trench transect deployed for the main study. The colocation of each group's different acoustic instruments provides an important opportunity to cross calibrate different technology, which can help transition seafloor geodesy out of the past proofing stage into a robust science. Training of a graduate student in acquisition and processing of the geodetic data will increase the workforce in this developing research area.
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 goal of this project was to deploy a novel suite of instrumentaiton for measuring the strain of the seafloor in a region offshore of Northern Chile that is expected to experience a great subduction zone earthquake and tsunami in the coming years. The deployment was arranged after the 2014 Iquique M8 earthquake. It was a joint collaboraiton between WHOI, GEOMAR, and the Universidad de Chile. The WHOI instrumentation was succesfully deployed in 2016 using the ship R/V Atlantis and the Remotely Operated Vehicle Jason. Unfortunately due to covid related complications and cruise restrictions we were never able to recover the WHOI instrumentation. In parallel, GEOMAR deployed and recovered a similar related suite of seafloor geodetic information. That instrumentation succesfully recorded seafloor strain in the updip part of the subduction zone.
The project provided at sea training for a number of students and engineers. In particular a group of Chilean scientists and students joined the cruise to learn the geodetic instrumentaiton. They also collected current data to be used in physical oceanography research.
After the final attempt at a recovery cruise was cancelled, the remaining funds were used to refurbish a seafloor borehole geodetic observatory that had previously been installed offshore of Vancouver Island in a similar subduction zone environment. That equipment was part of the Ocean Networks Canada and required repair. It has been fully refurbished using this award and is awaiting an opportunity for redeployment. A number of key components including seismometers, tiltmeters, data loggers, thermistors, wetmate connectors, and communications electronics were purchased, integrated and tested in an onshore borehole to prep them for eventual deployment offshore of Vancouver Island.
Last Modified: 05/08/2025
Modified by: Jeffrey J McGuire
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