
NSF Org: |
EAR Division Of Earth Sciences |
Recipient: |
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Initial Amendment Date: | August 11, 2016 |
Latest Amendment Date: | August 11, 2016 |
Award Number: | 1624612 |
Award Instrument: | Standard Grant |
Program Manager: |
Steven Whitmeyer
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
Start Date: | September 1, 2016 |
End Date: | August 31, 2020 (Estimated) |
Total Intended Award Amount: | $270,740.00 |
Total Awarded Amount to Date: | $270,740.00 |
Funds Obligated to Date: |
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History of Investigator: |
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Recipient Sponsored Research Office: |
118 COLLEGE DRIVE HATTIESBURG MS US 39406-0001 (601)266-4119 |
Sponsor Congressional District: |
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Primary Place of Performance: |
2609 West 4th St. Hattiesburg, MS MS US 39401-5876 |
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): |
Tectonics, EPSCoR Co-Funding |
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
There is an extensive instrumental, historical, and geological record of tsunamigenic-earthquakes originating from the northern and middle parts of the Japan Trench that documents the last several thousand years of earthquakes and tsunamis, including the magnitude 9 Tohoku earthquake in 2011. This earthquake ruptured five segments along the northern and middle parts of the Trench, but failed to rupture through the southern part, which is near metropolitan Tokyo. The seismic risk for this portion of the trench is uncertain because of the possibility that stress transferred southwards during the 2011 earthquake and that this part of the subduction zone is locked. Furthermore, the instrumental and historical record is sparse with only one tsunamigenic-earthquake on record (CE 1677 Empo earthquake) and lack of long-term geological data. A research team from University of Southern Mississippi and Rutgers University in collaboration with Japanese researchers will employ an innovative combination of field, laboratory (sedimentary, microfossil, and radiometric analyses), statistical, and modeling techniques to a series of possible tsunami deposits in order to determine the tsunami and earthquake history of the southern Japan Trench, data which is very important for anticipating future disasters. Besides providing an improved understanding of seismic risk in the Tokyo region, additional benefits to society include improved STEM education though outreach to middle school students and development of a globally competitive STEM workforce through training of graduate and undergraduate students and post-doctoral fellow mentoring.
The detection and characterization of tsunami deposits preserved in coastal sediments provides a long-term record of past earthquakes. This project focuses on three candidate-tsunami sands that are preserved in coastal rice fields in the Kujukuri beaches, a strand plain located on the Boso Peninsula approximately 50 km east of Tokyo. The identification of tsunami deposits using proxy analyses (grain size and microfossil), with Bayesian age-depth models and tsunami simulation models, will resolve whether the southern part of the trench can produce future earthquakes that are similar in size as the 2011 Tohoku event. Well-constrained ages for each candidate tsunami will permit an accurate estimation of the shoreline position, and thus, inundation distance at the time of deposition. By integrating these changing shoreline positions into previously developed tsunami simulation models (e.g., 2011 Tohoku and CE 1677 Empo models), the research team will test whether previous middle/northern or southern trench ruptures could have deposited the tsunami sands on the Boso Peninsula.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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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.
There is an extensive instrumental, historical and geological record of tsunamigenic-earthquakes originating from the northern and middle parts of the Japan Trench. The record documents the last several thousand years of earthquakes and tsunamis of known recurrence intervals and magnitudes, including the 2011 Tohoku earthquake (M 9.0). The 2011 earthquake ruptured five segments along the northern and middle parts of the Japan Trench, but failed to rupture through the southern part. Uncertainty surrounds the seismic risk for coastlines facing the southern part of the Japan Trench near metropolitan Tokyo because of the potential transfer of stress southwards during the 2011 earthquake, coupled with the locked nature of this part of the subduction zone. Furthermore, the southern part of the Japan Trench is part of a seismically complex region where three plate boundaries intersect (i.e., a triple junction): Japan Trench, Sagami Trough, and Izu-Bonin Trench.
Earthquake hazard assessments for the Tokyo Region, therefore, are complicated by the stacking of two subduction zones in a trench-trench triple junction where the oceanic Philippine Sea plate (PHS) not only underthrusts a continental plate (CON), but is also being subducted by the Pacific plate (PAC). Great earthquakes are recognized hazards from the CON/PHS (Sagami Trough) and CON/PAC (Japan Trench) plate boundaries, but not from the PHS/PAC (Izu-Bonin Trench) boundary. To improve our understanding of earthquake and tsunami hazards for the Tokyo Region, an innovative combination of field, laboratory (sedimentary, microfossil, and radiometric analyses), statistical, and modeling techniques were applied to a series of candidate tsunami deposits that our team discovered in 2013 as part of an NSF EAGER grant (EAR-1303881). These methods were applied to resolve a key unanswered question related to the long-term patterns of seismicity in the area of the triple junction: Is the Tokyo Region at risk of an earthquake and tsunami similar in magnitude and intensity as the 2011 Tohoku event?
The research team, consisting of members from the United States, Japan, and Canada, completed multiple field expeditions to the Kujukuri Beaches of the Boso Peninsula (~50 km east of Tokyo). Over 300 auger cores were collected, spanning a distance of over 50 km alongshore. These cores revealed stratigraphic, sedimentologic, and microfossil evidence for two tsunamis originating from one of three possible subduction zones within the triple junction. This study implicates the Izu-Bonin Trench (PHS/PAC plate boundary), a previously unconsidered earthquake source, in generating a large tsunami that is evidenced by sandy deposits along ~50 km of coastline at the Kujukuri Beaches. Dating to about 1,000 years ago, this inferred tsunami predates local written history by a few hundred years. The inland extent of its sand sheet is best explained in modeled scenarios by displacement on the Izu-Bonin Trench (minimum magnitude required = Mw 8.5). Until now, no geological evidence for an earthquake involving the PHS/PAC boundary has been discovered. This plate-boundary fault, previously undemonstrated, adds another source for earthquakes in Tokyo and tsunamis in the Pacific Ocean, highlighting the complex seismic hazard of the Tokyo Region. These results have direct impact on the disciplines of policy, hazard mitigation, and public hazard education. The findings concerning the previously unconsidered earthquake and tsunami source (Izu-Bonin Trench) have been requested by the Japanese government for inclusion in their national seismic hazard maps.
The outreach strategy developed as part of this study involved the participation of undergraduates, graduate students, government scientists, professors, and outreach coordinators in the United States, Japan, and Canada. The diverse activities to increase public awareness and education about earthquake hazards and paleoseismology included: (1) An educational program for middle school children in the United States and Japan regarding earthquake and tsunami hazards. The traveling lesson module was presented to middle school teachers via workshops in New Jersey. Pilarczyk assisted Professor Fujino (Tsukuba University) with a similar Japanese-based lesson module; (2) Concepts and results gained from this research were integrated into undergraduate and graduate courses at Rutgers University, University of Southern Mississippi, and Simon Fraser University. Sediment peels collected from Kujukuri cores formed the basis of laboratory exercises in several undergraduate courses at Simon Fraser University; and (3) Findings from this study were disseminated via a Pint of Science public lecture and a Curiosity Collider documentary called Ground Swell that was featured in Her Story: Canadian Women Scientists. The documentary short film is rooted in tsunami science but has a major focus on the importance of female mentorship in STEM subjects.
Last Modified: 01/25/2021
Modified by: Jessica Pilarczyk
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