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You searched for +publisher:"Colorado State University" +contributor:("Benz, Harley"). Showing records 1 – 2 of 2 total matches.

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Colorado State University

1. Cole, Hank M. Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica.

Degree: MS(M.S.), Geosciences, 2020, Colorado State University

Repeating 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. Advisors/Committee Members: Aster, Richard C. (advisor), McGrath, Daniel (committee member), Cheney, Margaret (committee member), Benz, Harley (committee member).

Subjects/Keywords: grounding line; icequakes; tides; ice shelf; seismology; Antarctica

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Cole, H. M. (2020). Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/212036

Chicago Manual of Style (16th Edition):

Cole, Hank M. “Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica.” 2020. Masters Thesis, Colorado State University. Accessed April 12, 2021. http://hdl.handle.net/10217/212036.

MLA Handbook (7th Edition):

Cole, Hank M. “Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica.” 2020. Web. 12 Apr 2021.

Vancouver:

Cole HM. Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica. [Internet] [Masters thesis]. Colorado State University; 2020. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/10217/212036.

Council of Science Editors:

Cole HM. Tidally induced seismicity at the grounded margins of the Ross Ice Shelf, Antarctica. [Masters Thesis]. Colorado State University; 2020. Available from: http://hdl.handle.net/10217/212036

2. McMahon, Nicole D. Automated event detectors utilized for continental intraplate earthquakes: applications to tectonic, induced, and magmatic sequences.

Degree: PhD, Geosciences, 2018, Colorado State University

Event detection is a crucial part of the data-driven science of seismology. With decades of continuous seismic data recorded across thousands of networks and tens of thousands of stations, and an ever-accelerating rate of data acquisition, automated methods of event detection, as opposed to manual/visual inspection, allow scientists to rapidly sift through enormous data sets extracting event information from background noise for further analysis. Automation naturally increases the numbers of detected events and lowers the minimum magnitude of detectable events. Increasing numbers and decreasing magnitudes of detected events, particularly with respect to earthquakes, enables the construction of more complete event catalogs and more detailed analysis of spatiotemporal trends in earthquake sequences. These more complete catalogs allow for enhanced knowledge of Earth structure, earthquake processes, and have potential for informing hazard mitigation. This study utilizes automated event detection techniques, namely matched filter and subspace detection, and applies them to three different types of continental intraplate earthquake sequences: a tectonic aftershock sequences in Montana, an induced aftershock sequence in Oklahoma, and a magmatic swarm sequence in Antarctica. In Montana, the combination of matched filtering and multiple-event relocation techniques provided a more complete picture of the spatiotemporal evolution of the aftershock sequence of the large intraplate earthquake that occurred near Lincoln, Montana in 2017. The study reveals movement along an unmapped fault that is antithetical to the main fault system trend in the region and demonstrates the hazards associated with a highly faulted and seismically active region encompassing complex and hidden structures. In Oklahoma, subspace detection methodology is used in combination with multiple-event relocation techniques to reveal movement along three different faults associated with the 2011 Prague, Oklahoma induced earthquake sequence. The study identifies earthquakes located in both the sedimentary zone of wastewater injection as well as the underlying crystalline basement indicating that faults traverse the unconformity. Injecting fluid into the overlying sediment can easily penetrate to the basement where larger earthquakes nucleate. In Antarctica, subspace detection is again used in a very remote intraplate region with sparse station coverage to detail the sustained and ongoing magmatic deep, long-period earthquake swarm occurring beneath the West Antarctic Ice Sheet and Executive Committee Range in Marie Byrd Land, Antarctica. These earthquakes indicate the present-day location of magmatic activity, which appears appear to have increased in intensity over the last few years. This dissertation contributes to the growing bodies of literature around three distinctly interesting types of seismicity that are not associated to the first order with plate tectonic boundaries. Large tectonic intraplate earthquakes are relatively uncommon. Induced seismicity has… Advisors/Committee Members: Aster, Richard C. (advisor), Schutt, Derek L. (committee member), Cheney, Margaret (committee member), Benz, Harley M. (committee member).

Subjects/Keywords: earthquakes; intraplate earthquakes; volcanic seismicity; induced seismicity; earthquake detection; seismology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

McMahon, N. D. (2018). Automated event detectors utilized for continental intraplate earthquakes: applications to tectonic, induced, and magmatic sequences. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/193146

Chicago Manual of Style (16th Edition):

McMahon, Nicole D. “Automated event detectors utilized for continental intraplate earthquakes: applications to tectonic, induced, and magmatic sequences.” 2018. Doctoral Dissertation, Colorado State University. Accessed April 12, 2021. http://hdl.handle.net/10217/193146.

MLA Handbook (7th Edition):

McMahon, Nicole D. “Automated event detectors utilized for continental intraplate earthquakes: applications to tectonic, induced, and magmatic sequences.” 2018. Web. 12 Apr 2021.

Vancouver:

McMahon ND. Automated event detectors utilized for continental intraplate earthquakes: applications to tectonic, induced, and magmatic sequences. [Internet] [Doctoral dissertation]. Colorado State University; 2018. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/10217/193146.

Council of Science Editors:

McMahon ND. Automated event detectors utilized for continental intraplate earthquakes: applications to tectonic, induced, and magmatic sequences. [Doctoral Dissertation]. Colorado State University; 2018. Available from: http://hdl.handle.net/10217/193146

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