Seismological constraints on the mechanics of intermediate-depth earthquakes in the Bucaramanga Nest
Abstract/Contents
- Abstract
- For all the progress that seismology has made in the last century, intermediate-depth earthquakes are a relatively poorly understood phenomenon. They occur at depths 50-300 km, where high temperatures and pressures prohibit traditional brittle shear failure. Intermediate-depth earthquakes frequently occur in concentrated regions of seismicity called "earthquake nests". One such nest, the Bucaramanga Nest, beneath northern Colombia, is the focus of this work. It is the smallest and densest cluster of intermediate-depth seismicity in the world. This clustered region of seismicity produces thousands of events each year. While the nest does not pose the hazard other intermediate-depth earthquake nests might (e.g. the Vrancea Nest, Romania), the nest is capable of producing moderate shaking such as in the M 6.2 event that occurred in the nest in early 2015. This high level of seismicity provides an opportunity to study characteristics of the nest and its earthquakes as a natural laboratory. This dissertation utilizes the tools of observational seismology to expand on processes of intermediate-depth seismicity with particular emphasis on constraining the underlying failure mechanism. To maximize the observations of nest seismicity, I develop a new and novel earthquake detection method that bridges the gap between general and specific earthquake detection algorithms. Through observations of these events, I find repeating and reverse-polarity repeating signals and explain how the timing and relative locations of these earthquakes are indicative of subduction processes at intermediate-depths. I am also able to perform a comprehensive search for small magnitude earthquakes and find the Bucaramanga Nest deviates from traditional Gutenberg-Richter magnitude-frequency distributions at the small end magnitude of the magnitude spectrum. I find multiple lines of evidence that support a thermal shear instability failure mechanism for these intermediate-depth nest earthquakes.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Barrett, Sarah Anne |
|---|---|
| Associated with | Stanford University, Department of Geophysics. |
| Primary advisor | Beroza, Gregory C. (Gregory Christian) |
| Thesis advisor | Beroza, Gregory C. (Gregory Christian) |
| Thesis advisor | Lawrence, Jesse |
| Thesis advisor | Warren, Jessica |
| Advisor | Lawrence, Jesse |
| Advisor | Warren, Jessica |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Sarah Anne Barrett. |
|---|---|
| Note | Submitted to the Department of Geophysics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Sarah Anne Barrett
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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