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Sallarès V, Prada M, Riquelme S, Meléndez A, Calahorrano A, Grevemeyer I, Ranero CR. Large slip, long duration, and moderate shaking of the Nicaragua 1992 tsunami earthquake caused by low near-trench rock rigidity. SCIENCE ADVANCES 2021; 7:7/32/eabg8659. [PMID: 34362735 PMCID: PMC8346212 DOI: 10.1126/sciadv.abg8659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Large earthquake ruptures propagating up to areas close to subduction trenches are infrequent, but when they occur, they heavily displace the ocean seafloor originating destructive tsunamis. The current paradigm is that the large seafloor deformation is caused by local factors reducing friction and increasing megathrust fault slip, or prompting the activation of ancillary faults or energy sources. As alternative to site-specific models, it has been proposed that large shallow slip could result from depth-dependent rock rigidity variations. To confront both hypotheses, here, we map elastic rock properties across the rupture zone of the M S7.0-M W7.7 1992 Nicaragua tsunami earthquake to estimate a property-compatible finite fault solution. The obtained self-consistent model accounts for trenchward increasing slip, constrains stress drop, and explains key tsunami earthquake characteristics such as long duration, high-frequency depletion, and magnitude discrepancy. The confirmation that these characteristics are all intrinsic attributes of shallow rupture opens new possibilities to improve tsunami hazard assessment.
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Affiliation(s)
| | - Manel Prada
- Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | | | - Adrià Meléndez
- Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | | | | | - César R Ranero
- Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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Upper-plate rigidity determines depth-varying rupture behaviour of megathrust earthquakes. Nature 2019; 576:96-101. [PMID: 31776513 DOI: 10.1038/s41586-019-1784-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 09/20/2019] [Indexed: 11/09/2022]
Abstract
Seismological data provide evidence of a depth-dependent rupture behaviour of earthquakes occurring at the megathrust fault of subduction zones, also known as megathrust earthquakes1. Relative to deeper events of similar magnitude, shallow earthquake ruptures have larger slip and longer duration, radiate energy that is depleted in high frequencies and have a larger discrepancy between their surface-wave and moment magnitudes1-3. These source properties make them prone to generating devastating tsunamis without clear warning signs. The depth-dependent rupture behaviour is usually attributed to variations in fault mechanics4-7. Conceptual models, however, have so far failed to identify the fundamental physical causes of the contrasting observations and do not provide a quantitative framework with which to predict and link them. Here we demonstrate that the observed differences do not require changes in fault mechanics. We use compressional-wave velocity models from worldwide subduction zones to show that their common underlying cause is a systematic depth variation of the rigidity at the lower part of the upper plate - the rock body overriding the megathrust fault, which deforms by dynamic stress transfer during co-seismic slip. Combining realistic elastic properties with accurate estimates of earthquake focal depth enables us to predict the amount of co-seismic slip (the fault motion at the instant of the earthquake), provides unambiguous estimations of magnitude and offers the potential for early tsunami warnings.
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Klaeschen D, Belykh I, Gnibidenko H, Patrikeyev S, von Huene R. Structure of the Kuril Trench from seismic reflection records. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb01186] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Beckers J, Lay T. Very broadband seismic analysis of the 1992 Flores, Indonesia, earthquake (Mw= 7.9). ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb01689] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Satake K, Bourgeois J, Abe K, Abe K, Tsuji Y, Imamura F, Lio Y, Katao H, Noguera E, Estrada F. Tsunami field survey of the 1992 Nicaragua earthquake. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/93eo00271] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Synolakis CE, Bardet JP, Borrero JC, Davies HL, Okal EA, Silver EA, Sweet S, Tappin DR. The slump origin of the 1998 Papua New Guinea Tsunami. Proc Math Phys Eng Sci 2002. [DOI: 10.1098/rspa.2001.0915] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Costas E. Synolakis
- Department of Civil Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Jean-Pierre Bardet
- Department of Civil Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - José C. Borrero
- Department of Civil Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Hugh L. Davies
- Geology Department, University of Papua New Guinea, University PO, NCD [Port Moresby], Papua New Guinea
| | - Emile A. Okal
- Department of Geological Sciences, Northwestern University, Evanston, IL 60208, USA
| | - Eli A. Silver
- Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA
| | - Suzanne Sweet
- Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA
| | - David R. Tappin
- British Geological Survey, Keyworth, Nottingham NG12 5GG, UK
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Tsuru T, Park JO, Takahashi N, Kodaira S, Kido Y, Kaneda Y, Kono Y. Tectonic features of the Japan Trench convergent margin off Sanriku, northeastern Japan, revealed by multichannel seismic reflection data. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900132] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bilek SL, Lay T. Depth dependent rupture properties in circum-Pacific subduction zones. GEOCOMPLEXITY AND THE PHYSICS OF EARTHQUAKES 2000. [DOI: 10.1029/gm120p0165] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Bilek SL, Lay T. Rigidity variations with depth along interplate megathrust faults in subduction zones. Nature 1999. [DOI: 10.1038/22739] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bilek SL, Lay T. Variation of interplate fault zone properties with depth in the japan subduction zone. Science 1998; 281:1175-8. [PMID: 9712578 DOI: 10.1126/science.281.5380.1175] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The depth dependence of physical properties along the Japan subduction zone interface was explored using teleseismic recordings of earthquake signals. Broadband body waves were inverted to determine the duration of rupture and source depth for 40 interplate thrust earthquakes located offshore of Honshu between 1989 and 1995. After scaling for differences in seismic moment, there is a systematic decrease in rupture duration with increasing depth along the subducting plate interface. This indicates increases in rupture velocity or stress drop with depth, likely related to variation in rigidity of sediments on the megathrust.
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Affiliation(s)
- SL Bilek
- Institute of Tectonics and Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA
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Johnson JM, Satake K. Estimation of seismic moment and slip distribution of the April 1, 1946, Aleutian tsunami earthquake. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97jb00274] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kanamori H, Kikuchi M. The 1992 Nicaragua earthquake: a slow tsunami earthquake associated with subducted sediments. Nature 1993. [DOI: 10.1038/361714a0] [Citation(s) in RCA: 284] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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