Evidence for Past Subduction Earthquakes at a Plate Boundary with Widespread Upper Plate Faulting: Southern Hikurangi Margin, New Zealand

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dc.contributor.utaustinauthorWallace, Laura M.en_US
dc.creatorClark, Kate J.en_US
dc.creatorHayward, Bruce W.en_US
dc.creatorCochran, Ursula A.en_US
dc.creatorWallace, Laura M.en_US
dc.creatorPower, William L.en_US
dc.creatorSabaa, Ashwaq T.en_US
dc.date.accessioned2016-10-28T19:51:20Z
dc.date.available2016-10-28T19:51:20Z
dc.date.issued2015-09en_US
dc.description.abstractAt the southern Hikurangi margin, New Zealand, we use salt marsh stratigraphy, sedimentology, micropaleontology, and radiocarbon dating to document evidence of two earthquakes producing coseismic subsidence and (in one case) a tsunami over the past 1000 yrs. The earthquake at 520-470 yrs before present (B.P.) produced 0.25 +/- 0.1 m of subsidence at Big Lagoon. The earthquake at 880-800 yrs B.P. produced 0.45 +/- 0.1 m of subsidence at Big Lagoon and was accompanied by a tsunami that inundated >= 360 m inland with a probable height of >= 3.3 m. Distinguishing the effects of upper plate faulting from plate interface earthquakes is a significant challenge at this margin. We use correlation with regional upper plate paleoearthquake chronologies and elastic dislocation modeling to determine that the most likely cause of the subsidence and tsunami events is subduction interface rupture, although the older event may have been a synchronous subduction interface and upper plate fault rupture. The southern Hikurangi margin has had no significant (M > 6.5) documented subduction interface earthquakes in historic times, and previous assumptions that this margin segment is prone to rupture in large to great earthquakes were based on seismic and geodetic evidence of strong contemporary plate coupling. This is the first geologic evidence to confirm that the southern Hikurangi margin ruptures in large earthquakes. The relatively short-time interval between the two subduction earthquakes (similar to 350 yrs) is shorter than in current seismic-hazard models.en_US
dc.description.departmentInstitute for Geophysicsen_US
dc.description.sponsorshipGNSen_US
dc.description.sponsorshipEQC Biennial Projecten_US
dc.description.sponsorshipNew Zealand Natural Hazards Research Platform and Foundation for Research Science and Technologyen_US
dc.identifierdoi:10.15781/T20Z7104Q
dc.identifier.citationClark, Kate J., Bruce W. Hayward, Ursula A. Cochran, Laura M. Wallace, William L. Power, and Ashwaq T. Sabaa. "Evidence for past subduction earthquakes at a plate boundary with widespread upper plate faulting: Southern Hikurangi Margin, New Zealand." Bulletin of the Seismological Society of America (Sep., 2015).en_US
dc.identifier.doi10.1785/0120140291en_US
dc.identifier.issn0037-1106en_US
dc.identifier.urihttp://hdl.handle.net/2152/43238
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialBulletin of the Seismological Society of Americaen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectnorth-islanden_US
dc.subjecthawkes bayen_US
dc.subjectgreat earthquakesen_US
dc.subjectcoastal wetlandsen_US
dc.subjectohariuen_US
dc.subjectfaulten_US
dc.subjectholocene earthquakesen_US
dc.subjectchile earthquakeen_US
dc.subjectsurface rupturesen_US
dc.subjectriveren_US
dc.subjectestuaryen_US
dc.subjectbeach ridgesen_US
dc.subjectgeochemistry & geophysicsen_US
dc.titleEvidence for Past Subduction Earthquakes at a Plate Boundary with Widespread Upper Plate Faulting: Southern Hikurangi Margin, New Zealanden_US
dc.typeArticleen_US

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