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New perspective on the transition from flat to steeper subduction in Oaxaca, Mexico, based on seismicity, nonvolcanic tremor, and slow slip

Fasola, Shannon Lee
http://orcid.org/0000-0003-3941-4828
http://rave.ohiolink.edu/etdc/view?acc_num=miami1461778598

Abstract Details

2016, Master of Science, Miami University, Geology and Environmental Earth Science.
We examine the along-strike transition from flat to steeper subduction in Oaxaca, Mexico to provide a better understanding of what controls the slab morphology. Prior studies have suggested the slab tends to tear along the transitions in dip as the slab rolls back. We determine the slab geometry based on local seismicity, nonvolcanic tremor (NVT), and slow slip utilizing a deployment of broadband seismometers and continuous GPS receivers distributed in and around Oaxaca. We construct depth contours of the subducting slab surface down to 100 km, which illustrate that the transition from flat to steeper subduction occurs rapidly via a sharper flexure than previously recognized. The prior catalog of NVT in Oaxaca is extended using the same method and additional stations that extend further west. The band of NVT follows the new slab contours, widening towards the west with the downdip extent gradually moving inland. The amount of NVT also correlates with the strength of an ultra slow velocity layer. There are no gaps in seismicity, NVT, or slow slip across the rapid transition in slab dip, further supporting the notion that the slab is not currently torn in the updip region. We propose that the sharp flexure is possible in this region due to bending moment saturation that leads to greater curvature in both the down-dip and along-strike directions. A similar set of observations in southern Peru suggests this is a viable alternative to tearing that accommodates the large strains from variable rates of slab rollback.
Michael Brudzinski (Advisor)
Brian Currie (Committee Member)
Elisabeth Widom (Committee Member)
Geophysics; Plate Tectonics
seismicity; nonvolcanic tremor; slow slip; subduction geometry; slab rollback; bending strength

Recommended Citations

Citations

  • Fasola, S. L. (2016). New perspective on the transition from flat to steeper subduction in Oaxaca, Mexico, based on seismicity, nonvolcanic tremor, and slow slip [Master's thesis, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1461778598

    APA Style (7th edition)

  • Fasola, Shannon. New perspective on the transition from flat to steeper subduction in Oaxaca, Mexico, based on seismicity, nonvolcanic tremor, and slow slip. 2016. Miami University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1461778598.

    MLA Style (8th edition)

  • Fasola, Shannon. "New perspective on the transition from flat to steeper subduction in Oaxaca, Mexico, based on seismicity, nonvolcanic tremor, and slow slip." Master's thesis, Miami University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1461778598

    Chicago Manual of Style (17th edition)

miami1461778598
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© 2016, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.