2018 IRIS Undergraduate Interns
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Brianna- Read Blog Entries
Project Title: Searching for magmatically induced, brittle-failure earthquakes within the lithospheric mantle beneath the Harrat Rahat volcanic field in Saudi ArabiaProject Description:(Click to expand)
This project is looking at locating magmatically induced, brittle-failure earthquakes within the lithospheric mantle beneath the Harrat Rahat volcanic field in northwestern Saudi Arabia. Brittle-failure earthquakes are quite small (magnitudes <2), but display distinct, repeating signals which have been observed in other Saudi Arabian volcanic fields. We will be using the Fingerprint and Similarity Thresholding (FAST) algorithm developed at Stanford to search large datasets from the area in a relatively small amount of time as compared to other methods which are used for similarity searching in seismology. The outcomes of this research will help inform volcanic and seismological hazard in the area around Harrat Rahat, as well as help to enlighten our understanding of the evolution and history of the Red Sea rift.
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Albert Aguilar- Read Blog Entries
Project Title: High resolution detection and source analysis of subduction zone earthquakes in Colombia and Costa RicaProject Description:(Click to expand)
The research will focus on new detection and analysis of seismicity in subduction zones: Shallow seismicity in Colombia and Costa Rica. The detection will be performed with template matching techniques and attemped with convolutional neuronal networks (ConvNetQuake). The research will also involve relocation and magnitude estimation. The new catalogs will serve as a basis for b-value estimates and eathquake source study (stress drop and radiated energy) relating these metrics with the tectonic context of the subduction zones.
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Ty- Read Blog Entries
Project Title: Using Tide Gauges to Understand Historical Slow-Slip Events in the Cascadian Subduction ZoneProject Description:(Click to expand)
This project seeks to use Tide Gauges as a way to detect vertical, geodetic deformation due to slow-slip earthquakes. While GPS stations can accomplish the same feat in the modern age, Tide Gauge records go back many decades beyond the earliest deployed GPS. However, Tide Gauges are subject to a wide variety of phenomena (changing water levels, changing tidal phase arrivals due to meteorological effects, etc.) which make the signal of the slow-slip earthquake difficult to make out. This team seeks to uncover a solid methodology to isolate this signal and trace back slow-slip earthquakes through the last century, which can shed light and provide valuable information on the fault mechanics and potential earthquake hazard of the Cascadian Subduction Zone.
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Siena Sage Collier- Read Blog Entries
Project Title: Physical seismic models of synthetic decomposed graniteProject Description:(Click to expand)
This project will demonstrate how angularity of sand grains affects the p-wave and s-wave velocity versus how they are in round grains. In previous studies, sand grains are modeled as spheres and predictions are made about how the degree of roundness changes the p and s wave velocity. This project will also examine how water saturation will change the velocity of seismic waves and the degree of so based on porosity.
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Sydney- Read Blog Entries
Project Title: Investigation of Seismometer Emplacement Techniques to Reduce Seismic Noise caused by Meteorological EventsProject Description:(Click to expand)
By coupling with the ground, wind causes ground motion that appears on seismic records as noise at a variety of frequencies. Several previous studies have taken wind measurements at one position and related it to signal on seismometers that were often quite a distance away. However, because wind speed and direction are such highly locally variable phenomena due to variations in topography, obstacles, and diurnal heating, it is likely that there will be differences in the wind speed/direction at different locations, which will therefore cause differences in the amount and
characteristics of seismic noise. The goal of my project is to investigate specifics of the spatial variability of wind using two weather sensors approximately 300 feet apart collocated with
several near-surface broadband seismometers. We will attempt to figure out whether it is possible to identify and/or quantify the relationship between wind speed and ground motion, and determine at which frequencies this noise is produced. Understanding this process could help to improve our ability to mitigate locally generated seismic noise sources.
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Will- Read Blog Entries
Project Title: Surface Wave Arrival Angles at the USArray Transportable ArrayProject Description:(Click to expand)
My research project focuses on using surface waves to image anomalies in the lithosphere with data from the USArray Transportable seismic network. To do this I will be investigating frequency-dependent arrival angles. An anomaly will cause the waves to bend away from the source-receiver great circle path. First the deformation will be measured and then validated using synthetic seismograms in a 3-dimensional Earth model. The difference between real observations and synthetics will be used to further refine the Earth model.
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Hannah- Read Blog Entries
Project Title: Determining the cause and nature of anomalous Rayleigh wave H/V ratio measurements in southern CaliforniaProject Description:(Click to expand)
My project is a part of a larger one that is using Rayleigh wave ellipticity (H/V ratios), geodetic, and gravity measurements to identify temporal changes in groundwater in southern California. I am working on a subset of the H/V ratio analysis. The Rayleigh wave ellipticity measurements of the region show anomalous behavior in the longer period data (15 seconds) at several different points in time. At these times, many stations measure a larger H/V ratio due to an unknown cause, unrelated to the subsurface structure. My task is to identify when, within the week-long average of measurements, the anomaly causing phenomena occurred. This will be done by performing 9 component cross correlation between all station pairs, stacking these results, converting from the frequency to the time domain, rotating to the radial-transverse-vertical frame, and calculating H/V measurements using the rms amplitudes of the waveforms near the maximums of the envelopes of each component, for increasingly smaller time frames (week, day, and, finally, hour). Once the time of interest is identified, I will find possible causes of the anomaly and decide which is most likely.
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Mariana- Read Blog Entries
Project Title: Detection and location of tectonic tremor in Colombia using broad-band seismological data.Project Description:(Click to expand)
Northern South America is a tectonically complex region in which deformation results from the interaction of three tectonic plates. The understanding of the dynamics of subduction processes in northern South America can be greatly improved if we have an approximation of how energy is released along the different segments of the margin. Subduction in this part of the world is highly segmented, and the mechanisms of energy release along the subduction zone highly variable. In particular, there is a
contrast between normal and flat subduction at ~5.5°N at the Pacific margin, whereas the nature of subduction at the Caribbean margin is not yet clear. Besides looking at seismicity patterns, identification and location of tectonic tremor can provide insight into the spatial variations of behavior of the convergent margin. By using available broad-band data from the Seismological Network of Colombia, we intend to detect seismic tremor.
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Alan- Read Blog Entries
Project Title: Studying the Mantle Transition Zone in West AntarcticaProject Description:(Click to expand)
Calculating receiver functions to study the transition zone in West Antarctica. The transition zone which is represented by two globally known boundaries (410 and the 660 km) which are are parameters in the deep earth that can be used to possibly see mantle upwelling/mantle plumes that can tie into tectonics of Antarctica
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Dory- Read Blog Entries
Project Title: Seismic Investigations for the Enhanced Geothermal Systems Collab Project at the Sanford Underground Research FacilityProject Description:(Click to expand)
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Kat- Read Blog Entries
Project Title: Surface Wave Imaging of the Shale Hills Critical Zone ObservatoryProject Description:(Click to expand)
This critical zone (CZ) is the outermost layer of the Earth and contains soil, bedrock, and various organisms. As the CZ has many unanswered questions surrounding it, such as how it forms and how it will change in the future, this study aims to gain knowledge of the structure of the CZ, specifically the CZ in the Shale Hill Critical Zone Observatory in Pennsylvania. The first portion of this project consists of an active-source experiment, where 4200 geophones and 62 3-component nodes will be deployed over a 300 x 300 m2 region of the Shale Hill watershed. The data from this experiment will then be processed and analyzed, with the final goal of creating a shear velocity model which will then be interpreted to learn about the structure of the CZ in the region.
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Lauren- Read Blog Entries
Project Title: Rayleigh Wave Tomography of Alaska Using Ambient NoiseProject Description:(Click to expand)
Ambient noise often caused by ocean waves and other natural phenomenon can be detected by seismometers and provide information about Earth's structure. Using data collected from 2014-2018 by the USArray Transportable stations in Alaska and measuring Rayleigh wave phase velocities over a 5-25 s period will provide information about the Earth's crust.
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Tara- Read Blog Entries
Project Title: Better parameterizing strong ground motions in the USGS ShakeMap for the assessment of landslide and liquefaction hazardProject Description:(Click to expand)
My project will be working on the ShakeMap program developed by the USGS Earthquake Hazards Program. These ShakeMaps provide near-real-time information on significant earthquakes. Currently, this program can provide information on the magnitude, peak ground velocity, peak ground acceleration, and spectral acceleration. I will be working on adding parameters for duration and Arias intensity. These factors can affect the potential for landslide or liquefaction hazards, so this project will be useful in helping us predict these hazards.
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James Pippin- Read Blog Entries
Project Title: High-resolution Seismic Study of the Mid-Lithospheric discontinuity in the Precambrian Craton of North America using Harmonic Decomposition of Forward Scattered Body WavesProject Description:(Click to expand)
Based off previous research that has viewed the receiver functions to understand the Lithosphere and Asthenosphere Boundary (LAB), they come up with this discontinuity within the Lithosphere. This discontinuity is known as the Mid-Lithosphere Discontinuity. With the aid of HPC processes, we plan on developing a workflow that can use Earthscope data found across the United States from various array networks and automate a process to develop harmonic data sequences to understand the anisotropic properties in the lithosphere, primarily to understand and characterize the Mid-Lithosphere Discontinuity.
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Joey Renzaglia- Read Blog Entries
Project Title: Seismic Refraction Imaging of the Shale Hills Critical Zone ObservatoryProject Description:(Click to expand)
The critical zone (CZ) represents the outermost layer of the Earth where interactions between the atmosphere, soil, bedrock, and organisms regulate the formation of life sustaining
resources. For many decades investigating the deep CZ (> 5 m) where the important regolith/bedrock boundary sits and where water reservoirs reside was largely inaccessible owing to the time and cost of drilling/hand augering. Recent advances in standard geophysics methods and instrumentation now allow us to probe the CZ at previously inaccessible scales and depths. Despite extensive research into the CZ, fundamental questions remain regarding how the CZ forms, how the CZ evolves, and how the CZ will change in the future. This project will consist of 4200 geophones and 62 3 component nodes over a 300 x 300 m2 area. I will be tasked with processing and analyzing the dataset. Initially, I will pick first arrivals on refraction lines and develop a velocity model. Eventually all of this will lead to interpretability and understanding the subsurface structure.
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Julia Rosenblit- Read Blog Entries
Project Title: Rate changes of west Texas earthquakes tracked using array processing methods.Project Description:(Click to expand)
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Harrison- Read Blog Entries
Project Title: Systematic Studies of Microearthquake Detections and Fault Structures in ChinaProject Description:(Click to expand)
My project focuses on identifying and locating possible repeating earthquakes that are associated with the 2013 Lushan Ms7.0 earthquake in China. During this event, slip mainly occurred along the deeper parts of the fault. It is possible that the upper area may be slipping slowly and exhibiting repeating events. By identifying and locating these repeating events, the spatial and temporal evolution of the fault can be better understood.
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David- Read Blog Entries
Project Title: Searching for Anisotropy in Australian CrustProject Description:(Click to expand)
Th focus of this project is to better understand the complicated nature of the Australian Crust. Composed of several different cratons, Australia is home to very rich and complicated geology. Through analyzing data from 6 different seismic stations throughout the continent, I will attempt to model the layers of anisotropy in the continental crust. This will be done through analysis using Ps receiver functions for the different seismic stations. Then through modeling, I will be able to determine the rich tectonic history and the paleo-deformation direction of the region.
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Mitchell Spangler- Read Blog Entries
Project Title: Systematic Studies of Microearthquake Detections and Fault StructuresProject Description:(Click to expand)
We will be using a variety of detection methods to expand the earthquake catalog and gain a better understanding of seismic evolution. We want to examine how this can relate to fault zone structures and processes. I will mainly be focused on using the Matched Filter Technique.
Essentially, smaller earthquakes, such as foreshocks and aftershocks, can be vital to understanding the seismic evolution of a region. However, these events are so small that they are often simply not detectable by the human eye. This is where the Matched Filter Technique is applied. It works by starting out with a template. A template is a known earthquake in a particular region that has had its phases picked. This template is then compared to the continuous waveform data, and cross correlation between signals is computed. A cross correlation value ranges from -1 to 1. A value of 1 means that the events are a perfect match, and a cross correlation of -1 means that the events are exactly opposite in polarity. The events are then stacked. Using this method, we hope to provide a more complete catalog of earthquakes.
For my project, my study region is the Sichuan region in China. I will be examining the Wenchuan earthquake that occurred in 2008. I hope to investigate whether or not there is evidence that this event caused remote triggering in several different regions throughout China.
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Michael_Hubenthal- Read Blog Entries
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