Geology topics

Catherine M. Snelson

Publications and source records attributed to Catherine M. Snelson.

4 recordsLinked to original sources

USGS2015

Summer of Applied Geophysical Experience (SAGE): Training for our future geoscientists

Energy and natural resources are crucial to the sustainability of worldwide economies, security, and overall well-being. However, the future workforce in the energy and natural-resources sector is at risk, and meeting the challenges of this dwindling workforce requires well-educated geoscientists in exploration and applied geophysics and related geoscience and technology disciplines. Programs such as geophysical field courses that are supported by SEG and industry, in partnership with academic institutions and government laboratories, are important approaches to maintaining and enhancing expertise in exploration geophysics. One example of a geophysical field course devoted to educating our future workforce is the Summer of Applied Geophysical Experience (SAGE), a four-week program based in Santa Fe, New Mexico, designed to actively engage students in all phases of applied geophysical research. SAGE is a unique educational experience that combines teaching and research as a partnership among universities, industry, government agencies, and professional societies. SAGE teaches the principles and applications of refraction and reflection seismology, magnetics, gravity, GPS, heat flow, several electromagnetic (EM) methods, and ground-penetrating radar (GPR) in a field-based, hands-on setting. More than 850 students and qualified professionals have attended SAGE, many of whom have gone on to become leaders in academia, industry, and government. SAGE students are exposed to the exciting challenges that face earth scientists today, and they develop skills that are necessary to address the world's growing energy demands. Examples of SAGE research projects include mapping archaeological sites and tectonic structure and investigating water and geothermal resources in the Rio Grande rift.

Leading Edge (Tulsa, OK)↗

USGS2011

Urban seismic experiments investigate Seattle fault and basin

In the past decade, Earth scientists have recognized the seismic hazards that crustal faults and sedimentary basins pose to Seattle, Washington (Figure 1). In 1998, the US. Geological Survey and its collaborators initiated a series of urban seismic studies of the upper crust to better map seismogenic structures and sedimentary basins in the Puget Lowland. These studies are called the Seismic Hazard Investigations of Puget Sound (SHIPS). In March 1998, we conducted our first SHIPS study, an investigation of the upper crustal structure of the Puget Lowland, using marine airgun sources and land recorders [ Fisher et al. , 1999].The study was nicknamed Wet SHIPS. In September 1999, we obtained a seismic refraction line to study the upper crustal structure in the Seattle area in a land-based study nicknamed Dry SHIPS [ Brocher et al. , 2000] (Figure 1). In March 2000, we recorded the demolition of the Seattle Kingdome sports stadium using a dense array of seismic recorders for a detailed site response study; this study was nicknamed Kingdome SHIPS (Figure 1).

Washington↗

USGS2002

Implosion, earthquake, and explosion recordings from the 2000 Seattle Kingdome Seismic Hazards Investigation of Puget Sound (SHIPS), Washington

This report describes seismic data obtained in Seattle, Washington, March 24-28, 2000, during a Seismic Hazards Investigation of Puget Sound (SHIPS). The seismic recordings obtained by this SHIPS experiment, nicknamed Kingdome SHIPS, were designed to (1) measure site responses throughout Seattle and to (2) help define the location of the Seattle fault. During Kingdome SHIPS, we recorded the Kingdome implosion, four 150-lb (68-kg) shots, and a M w = 7.6 teleseism using a dense network of seismographs deployed throughout Seattle. The seismographs were deployed at a nominal spacing of 1 km in a hexagonal grid extending from Green Lake in the north to Boeing Field in the south. The Seattle Kingdome was a domed sports stadium located in downtown Seattle near the Seattle fault. The Seattle Kingdome was imploded (demolished) at 8:32 AM local time (16:32 UTC) on March 26 (JD 086), 2000. The seismic energy produced by implosion of the Kingdome was equivalent to a local earthquake magnitude of 2.3. Strong impacts produced by the implosion of the Kingdome generated seismic arrivals to frequencies as low as 0.1 Hz. Two shots located north of the Seattle fault, where the charges were detonated within the ground water column (Discovery and Magnuson Parks), were much more strongly coupled than were the two shots to the south of the Seattle fault, where the shots were detonated above the water table (Lincoln and Seward Parks). Thirty-eight RefTek stations, scattered throughout Seattle, recorded the M w = 7.6 Japan Volcano Islands earthquake (22.4°N, 143.6°E, 104 km depth) of 28 March 2000 (JD 088). This teleseism produced useful signals for periods between 4 and 7 seconds. Only a few recordings of small magnitude local earthquakes were made, and these recordings are not presented. In this report, we describe the acquisition of these data, discuss the processing and merging of the data into common shot gathers, and illustrate the acquired data. We also describe the format and content of the archival tapes containing the SEGY-formatted, common-shot gathers.

Washington↗

USGS2000

Report for explosion and earthquake data acquired in the 1999 Seismic Hazards Investigation of Puget Sound (SHIPS), Washington

This report describes the acquisition, processing, and quality of seismic reflection and refraction data obtained in the Seattle basin, central Puget Lowland, western Washington, in September 1999 during the Seismic Hazards Investigation of Puget Sound (SHIPS). As a sequel to the 1998 SHIPS air gun experiment (also known as 'Wet SHIPS'), the 1999 experiment, nicknamed 'Dry SHIPS,' acquired a 112-km-long east-west trending multichannel seismic reflection and refraction line in the Seattle basin. One thousand and eight seismographs were deployed at a nominal spacing of 100 meters, and 29 shot points were detonated at approximately 4 km intervals along the seismic line. The wide-angle seismic profile was designed to (1) determine the E-W geometry of Seattle basin, (2) measure the seismic velocities within the basin, and (3) define the basement structure underlying the Seattle basin. In this report, we describe the acquisition of these data, discuss the processing and merging of the data into common shot gathers, and illustrate the acquired profiles. We also describe the format and content of the archival tapes containing the SEGY-formatted, common-shot gathers. Data quality is variable, but useful data were acquired from all 29 shot points fired along the Dry SHIPS seismic line. The data show pronounced travel time delays associated with the low velocity sedimentary rocks filling the Seattle basin. Thirty-five REFTEK stations, deployed at 4 km intervals along the Dry SHIPS line, recorded 26 regional earthquakes and blasts and 17 teleseismic events, including the main shock and several aftershocks of the Mw=7.6 Chi-Chi (Taiwan) earthquake of 9/20/1999. The teleseismic recordings of the Chi-Chi (Taiwan) mainshock provide useful signals down to 10 second periods. They document a significant (factor between 5 and 10) focusing of compressional- and shear-wave energy by the Seattle basin at periods between 1 and 2 seconds relative to 'bedrock' sites east and west of the basin. Signal durations in the Seattle basin were also substantially increased relative to 'bedrock' sites in the Olympic peninsula and Cascade foothills.

Open-File Report↗