2012


Breanna Skeets

Jenny Nakai


Years participated in RESESS:
2012


An Overview

Major: Geophysics
Academic Affiliation: Colorado School of Mines
Research Mentor: Anne Sheehan, CU
Writing Mentor: Lon Abbott, CU
Graduate Student Mentors: Erin Leckey, Daniel Zietlow, Will Levandowski, CU


Biography

Jenny grew up in a lot of places: the Navajo Nation, Houston, American Samoa, and Albuquerque. She believes that research in earth sciences is increasingly important to deal with the resource and environmental challenges that we face today. Outside of studying, she enjoys organizing community events, hiking, running, and being outdoors. Her ultimate goal is to work as a geophysicist, researching global environmental problems and using her experience to educate communities.


Abstract

Using the USArray seismic data to study earthquakes of the Rio Grande rift

Broadly distributed deformation across the Rio Grande rift may indicate that low levels of seismicity are widespread in New Mexico. To understand this seismicity and its tectonic significance, it is desirable to construct a catalog of low magnitude earthquakes. The first step in creating such a catalog for New Mexico is distinguishing mine blasts from earthquakes in the USArray Array Network Facility (ANF) catalog. We examine nine regions that show concentrated seismic activity within a 40 km diameter to compare event frequency with event depth, magnitude, and time of day. For the time period studied, 2007 to 2010, the ANF catalog events show magnitudes down to 1.2 compared to 2.5 in the USGS catalog and are more spatially comprehensive. The event depth is a good way to distinguish between mine and non-mine events, provided that the depth error and anomalous events near mines at depths greater than 15 km are examined. Event magnitude distributions of non-mine events have a higher standard deviation of magnitude and a higher skewness, which tends to be positive. The time of day is a good indicator of mine and non-mine events because the mine events happen between sunrise and sunset. If a group of events is located near a mine, shows depths near 0 km, shows a relatively low standard deviation about a mean magnitude, and happens during the day, then it is likely a mine blast. In future work, the time of day, depth, magnitude, and magnitude cumulative distributions may be used to examine clusters of small magnitude events. Low magnitude events may be used in combination with GPS strain rate data to describe active deformation of the Rio Grande rift.