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Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica

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dc.contributor.authorCole, Hank M., author
dc.contributor.authorAster, Richard C., advisor
dc.contributor.authorMcGrath, Daniel, committee member
dc.contributor.authorCheney, Margaret, committee member
dc.contributor.authorBenz, Harley, committee member
dc.date.accessioned2020-09-07T10:08:40Z
dc.date.available2020-09-07T10:08:40Z
dc.date.issued2020
dc.description.abstractRepeating swarms of local icequakes were recorded by broadband seismograpghs deployed near the grounding line of the Ross Ice Shelf, Antarctica from late 2014 to early 2017. Swarms commonly persist for over six hours and contain thousands of events. Most swarms are induced or enhanced by tidal forcing. The number of events and event amplitudes in a swarm is most correlated with the modeled tide range. Some swarms only occur during cold periods of the austral winter. Icequakes are cataloged using a cross-correlation detector after building a template library from clustered STA/LTA picks and epicenters are estimated for high quality events. Events can be classified into four broad categories. The first event type is the most common (>95% of events) and occurs in diurnal swarms at all times of year. This type of event is interpreted to be sourced by propagation of near surface crevasses due to enhanced tensile stress from downward flexure of the ice shelf during falling tide. The second type of event has similar waveforms but occurs at the crest of large spring tides and appears to have an englacial or basal source. The third type of event is likely sourced from within the firn, possibly related to densification. It is also observed at stations in the ice shelf interior, but appears enhanced by tides at stations near the grounding line. The fourth type of event is only observed at a station on the Steershead Ice Rise. These are sweeping harmonic tremors lasting up to 8 s that start at low frequency and then tail upwards into an impulse like signal. This work characterizes these icequake types and their correlation to tidal and environmental forcing. It also details a single station event location scheme that is to used to further interpret events by finding their back azimuth with a polarization analysis and estimate their source-receiver distance with two methods. These observations provide insight into the deformation and brittle fracture at the grounded margins of the Ross Ice Shelf.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierCole_colostate_0053N_16180.pdf
dc.identifier.urihttps://hdl.handle.net/10217/212036
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2020-
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectgrounding line
dc.subjecticequakes
dc.subjecttides
dc.subjectice shelf
dc.subjectseismology
dc.subject.lcshAntarctica
dc.titleTidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineGeosciences
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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