Earth and Planetary Sciences
Date of Award
Doctor of Philosophy (PhD)
Chair and Committee
Recent advances in seismic instrumentation have allowed researchers to undertake focused investigations of regions previously inaccessible. From the bottom of the sea to the coldest, driest places on earth, we are now able to deploy seismometers to remote locations and be certain of collecting large amounts of useable data. By focusing regionally scaled seismic arrays in locations of tectonic and geodynamic interest we are able to better image the structure of these regions and place them in a global framework. This is particularly important in regions such as Antarctica and the ocean bottom where more traditional tools such as geologic mapping and sampling are difficult, if not currently impossible. This volume utilizes information garnered from several temporary deployments to such locations. In chapter 2 we use data collected from ocean bottom seismometers in the Mariana Islands to investigate the implications of along-arc extension. Small earthquakes that go undetected by the large global seismic network are detected by a temporary ocean bottom seismic array. The locations and timing of this seismicity place constraints on along-arc extension, an important arc process. In chapter 3 we use data collected by a short-term seismic array designed to detect and locate aftershocks associated with the May 3, 2006 MW8.0 Tonga earthquake. The fault mechanism of this earthquake is unusual and has important implications for tsunami hazard associated with the Tonga subduction zone. Through high precision location of aftershocks, we are able to determine the updip and downdip limits of seismicity associated with the mainshock. We are also able to relocate the mainshock location to a high degree of precision. In chapters 4 and 5 we utilize data from seismic arrays in Antarctica to image the crust and upper mantle structure of specific regions of interest using teleseismic surface waves. We focus our efforts on the Gamburtsev Subglacial Mountains in Chapter 4. This mountain range is located in the center of the East Antarctic Ice Sheet and their origin is enigmatic. Through high-resolution surface wave tomography possible only with a seismic array located above them, we are able to determine the lithospheric age and crustal thickness of the mountains. This study has important implications for determining the most recent age of uplift and their tectonothermal history. Finally, in chapter 5 we utilize data from three separate temporary deployments to image the crust and upper mantle of the Antarctic continent from the Gamburtsev Subglacial Mountains, across the Transantarctic Mountains that define the boundary between East and West Antarctica to Marie Byrd Land. This study encompasses nearly nine million square kilometers of the Antarctic continent.
Heeszel, David, "Surface Wave Derived Shear Velocity Structure of the Gamburtsev Subglacial Mountains, Transantarctic Mountains, and West Antarctica and Shallow Seismicity of the Mariana and Tonga Subduction Zones" (2011). All Theses and Dissertations (ETDs). 586.