Studies of Seismic Sources in Antarctica Using an Extensive Deployment of Broadband Seismographs
This dissertation is the first comprehensive study reporting the seismicity of Antarctica utilizing year-round recordings from autonomous instruments installed on the continent itself. I first examine the general seismic nature of the continent using locally deployed seismographs in both East Antarc...
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| Format: | Text |
| Language: | English |
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Washington University Open Scholarship
2014
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| Online Access: | https://openscholarship.wustl.edu/etd/1319 https://openscholarship.wustl.edu/cgi/viewcontent.cgi?article=2319&context=etd |
| Summary: | This dissertation is the first comprehensive study reporting the seismicity of Antarctica utilizing year-round recordings from autonomous instruments installed on the continent itself. I first examine the general seismic nature of the continent using locally deployed seismographs in both East Antarctica and West Antarctica. I detect and locate seismic events using the traditional first arriving impulsive P and S waves as well as events classified as 'slow' earthquakes with no impulsive P-waves. I find evidence of tectonic events in East Antarctica (representing intraplate earthquakes within a stable craton), icequake events in the Transantarctic Mountains (associated with active alpine glaciers), and icequake events at calving glaciers along the coastline. In West Antarctica I find tectonic earthquakes, icequakes, and tectonic events related to volcanism. I do not find evidence of tectonic events in West Antarctica that would indicate rifting is currently active. I also find two main sources of 'slow' seismicity: calving along Vanderford glacier and tidally modulated stick-slip motion of the Whillans Ice Stream. I further examine two types of events found through my review of the seismicity of Antarctica. I show that a cluster of events located in West Antarctica near the Marie Byrd Land linear volcanic chain the Executive Committee Range (ECR) are deep long period seismic events associated with the ongoing volcanism of the ECR. I provide several lines of evidence including the age progression of the exposed volcanic line as well as radar images featuring a recent ash layer supporting the continued magmatic activity in the ECR. My final investigation is into a new type of icequake in East Antarctica associated with wind-glazed small-scale crevasse features. The wave trains are dominated by surface wave energy and an apparent lack of body wave energy. I demonstrate that these events are sourced in the upper firn layers and can be used to determine firn thickness in East Antarctica by inverting group velocity ... |
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