Double-difference relocation of earthquakes at Uturuncu Volcano, Bolivia, and Interior Alaska
dc.contributor.author | Hutchinson, Laura | |
dc.date.accessioned | 2015-10-28T01:16:23Z | |
dc.date.available | 2015-10-28T01:16:23Z | |
dc.date.issued | 2015-08 | |
dc.identifier.uri | http://hdl.handle.net/11122/6093 | |
dc.description | Thesis (M.S.) University of Alaska Fairbanks, 2015 | en_US |
dc.description.abstract | In order to reliably interpret seismic patterns, we must have reliable earthquake locations. To improve our catalog locations, I incorporate cross-correlations into double-difference earthquake relocations to generate high precision relative locations. I perform relocations for two regions, one volcanic and one tectonic. At Uturuncu volcano, I incorporate a wealth of previous studies to present a picture of the processes at play. Seismic, gravity, InSAR, and electromagnetic studies all show that there is a magma body underlying the entire region, and chemical studies suggest that this magma body (the Altiplano-Puna Magma Body, or APMB) is the source of the large ignimbrite eruptions that have occurred in the past. The recent uplift has been modeled as a new batch of magma rising off the APMB, beginning the ascent as a diapir. My relocation results indicate that the seismicity aligns with the top of one of the imaged low velocities zones, which I interpret as a diaper beneath Uturuncu. The earthquakes mark the depth at which the crust is cool enough for brittle deformation. I also perform cross-correlations to determine families of similar events. These families are located around the summit of Uturuncu and display a radial pattern. This suggests that they are due to local volcanic stresses, such as inflation of the volcano, rather than regional stresses. In Interior Alaska, I study a region that is very seismically active, yet has no mapped Holocene faults. There are a series of seismic zones in the area, each comprised of NNE-striking seismic lineations. I perform earthquake relocations on 40 years worth of seismicity in order to refine and interpret fault planes. I additionally examine three earthquake sequences in the Minto Flats Seismic Zone (MFSZ). These earthquakes are large enough (≥M5) to produce an aftershock sequence to map out the rupture plane. I find that two of the three earthquakes occurred on WNW-striking planes, roughly perpendicular to the dominant direction of the seismic zone. The third earthquake ruptured along a NNE-striking plane but generated a WNWESE halo of aftershocks, suggesting that the basement is highly fractured in the region. The NW pattern that I find for the three sequences falls in line with my findings for the rest of the Interior: there are a series of NE-striking faults that are cut by NW-striking faults. Throughout the Interior, these faults cross at approximately 60°, suggesting that they are conjugate faults. I believe that the three earthquake sequences in the MFSZ are also conjugate faults and are a part of the broader conjugate system throughout the Interior. | en_US |
dc.language.iso | en_US | en_US |
dc.title | Double-difference relocation of earthquakes at Uturuncu Volcano, Bolivia, and Interior Alaska | en_US |
dc.type | Thesis | en_US |
dc.type.degree | ms | en_US |
dc.identifier.department | Department of Geosciences | en_US |
dc.contributor.chair | West, Michael | |
dc.contributor.committee | Christensen, Douglas | |
dc.contributor.committee | Freymueller, Jeffrey | |
refterms.dateFOA | 2020-03-05T10:42:07Z |
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