An attempt to reconstruct 2700 years of seismicity using deep-sea turbidites offshore eastern Taiwan

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Title:	An attempt to reconstruct 2700 years of seismicity using deep-sea turbidites offshore eastern Taiwan
Authors:	林殿順;Lehu, Rémi;Lallemand, Serge;Ratzov, Gueorgui;Babonneau, Nathalie;Hsu, Shu-Kun;Lin, Andrew T.;Dezileau, Laurent
Contributors:	地球科學學院地球科學學系
Keywords:	Caesium 137;Calibration;Cesium isotopes;Cesium radioisotopes;Clay;Core sampling;Cores;Coring;Cruises;Deep sea;Deep water;Earth Sciences;Earthquakes;Fluvial sediments;Gravity;Instability;Lead isotopes;Offshore;Paleolimnology;Radiocarbon dating;Radiometric dating;Rivers;Sciences of the Universe;Sedimentary facies;Sedimentation;Sedimentation & deposition;Seismic activity;Seismic stability;Seismicity;Seismology;Slope stability;Tectonics;Turbidites;Turbidity;Turbidity currents
Date:	2016-12-05
Issue Date:	2026-04-23 11:28:11 (UTC+8)
Publisher:	Elsevier;Amsterdam: Elsevier BV
Abstract:	摘要： The Taiwan area, where the Philippine Sea Plate collides with Eurasia, is one of the most seismically active areas in the world and has been consequently struck repeatedly by destructive earthquakes. To better constrain the occurrence of large earthquakes, we have conducted two cruises in 2012 and 2013 from which five piston, gravity and box-cores were retrieved from selected sites in targeted areas that contain continuous and accurate turbidite deposition offshore eastern Taiwan. Forty-seven turbidite layers deposited between 675 BC and 2012 AD have been described in the cores with facies varying from silty clay to coarse sand. We modeled each turbidite layer using the sedimentation rate deduced from radiocarbon age measurements performed on planktonic foraminifers. Precise dating based on 210Pb-137Cs chronology provided ages for the XXth century turbidites. Coring sites' locations, biotic association within turbidites beds and seismic calibration over the instrumental period, suggest that earthquakes are the most likely triggering mechanisms of turbidity currents over the last 2700 years. Calibration of correlations between turbidites and instrumental earthquakes allowed us to determine the minimum magnitude of recorded events (Mw = 6.8) and the maximum distance between the epicenter and the slope failure. Turbidites' synchroneity between cores has been tested but results showed that this criterion cannot be used in our study area because of the high level of seismicity, i.e., a M > 6.8 earthquake recurrence interval much smaller than the uncertainty on radiocarbon ages. The excellent accuracy of dating allows correlating all the turbidites deposited since 1920 with instrumental earthquakes. For each core, we established a return time ranging between 112 and 147 years for the period pre-1900 and ~ 27 and 34 years for the period post-1900. The discrepancy between pre-1900 and post-1900 recurrence either suggests, that slope stability varies, with higher slope instability after 1900 possibly due to increased sediment delivery by rivers. 出版者： Amsterdam: Elsevier BV 出版日期： 2016-12-05 出處： Tectonophysics, 2016-12, Vol.692, p.309-324 資源來源： Elsevier ScienceDirect Journals Complete 版權： Copyright Elsevier BV Dec 5, 2016 版權： licence_http://creativecommons.org/publicdomain/zero 識別號： ISSN: 0040-1951 識別號： EISSN: 1879-3266 識別號： DOI: 10.1016/j.tecto.2016.04.030
Appears in Collections:	[Department of Earth Sciences ] journal & Dissertation

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