| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | April 19, 2017 |
| Latest Amendment Date: | April 19, 2017 |
| Award Number: | 1649821 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Robin Reichlin
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | May 1, 2017 |
| End Date: | April 30, 2020 (Estimated) |
| Total Intended Award Amount: | $137,201.00 |
| Total Awarded Amount to Date: | $137,201.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
341 PINE TREE RD ITHACA NY US 14850-2820 (607)255-5014 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
2122 Snee Hall Ithaca NY US 14850-2820 |
| 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): |
PREEVENTS - Prediction of and, Geophysics |
| Primary Program Source: |
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| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The recent surge in induced seismicity in the Midwestern United States, during which Oklahoma has catapulted past California in seismicity rate, has created controversy, captured the attention of the general public, and influenced policy. As a result, induced seismicity has become a focal point of earthquake science in the United States over the last few years; however, much remains to be learned about the mechanisms of induced seismicity. In this research the well-recorded 2011 Prague, OK earthquake sequence will be used to investigate deformation on a scale not commonly obtainable in seismicity studies (earthquake location with precision ~10 meters). Such well-located earthquakes allow for better understanding of how complex faults fail. Furthermore, laboratory experiments on the rocks from the Prague area will provide information on how strong and stable the faults are, and how pumping fluids into the faults might promote earthquakes.
The Prague sequence contains three earthquakes ¡Ý Mw5 and their robust aftershock sequences, as well as the foreshock sequences for two large events. The precision with which the Prague earthquakes can be located allows the failure processes to be considered on a scale comparable to fault structures measured in studies of exhumed faults. In addition, complementary laboratory experiments on lithologies from the Prague area will allow study of the effects of fluid pressure on fault strength and stability. The ultimate goal is to use the Prague dataset to probe the influence of fluid pressure and fault zone complexity on earthquake nucleation, propagation, and arrest. Specifically this work will address the following questions: 1) Do the faults near Prague show precursory activity that could be used to forecast rupture? 2) How does complex fault geometry control rupture? and 3) How do fault strength, strength heterogeneity, and fault stability play a role in induced earthquakes?
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.
Continuous seismic waveform data were acquired in the aftershock zone of the Prague, Oklahoma earthquake, the largest known earthquake to occur within the state of Oklahoma in recorded times. The data were recorded over a time period of three months. Seismometers were deployed surrounding the entire fault rupture zone. Both short-period and broadband instruments were deployed. These waveform data were analyzed both by hand and by automated data analysis, and were used to develop an earthquake catalog consisting of the time and location of each earthquake recorded. The catalog includes very small magnitude earthquakes of magnitude zero and below, as well as aftershocks of approximately magnitude 3. Earthquakes delineate both the main fault zone, and intersecting and offset faults, indicating that numerous faults in the local region around the fault were activated in the time period following the main earthquake rupture. The catalog and waveforms were then analyzed to identify earthquakes that occurred in the same location in the subsurface multiple times, rupturing the same fault patch over and over, which are called "repeating earthquakes". These repeating earthquakes provide information about the likely properties of the fault on which they occur. These earthquakes can be used to better understand possible differences in physical properties between portions of faults which host repeating earthquakes, commonly seen on creeping sections of faults, and fault segments on which they are not recorded.
Last Modified: 01/27/2021
Modified by: Kathleen M Keranen
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