J. Arthur Snoke: Research

Research Interests

Earthquake seismology, both theoretical and observational. Specific areas of interest include crustal and upper mantle structure and computational seismology (seismic constraints on the geometry in subduction zones and the deep structure of continental shields along with the computational techniques used); seismic source studies (interpretation of source and spectral parameters, seismic source scaling relations, temporal and spatial changes in seismicity in seismically active regions); and network seismology (focal mechanisms, instrument calibration, earthquake hazard mitigation in regions with sparse seismicity but potentially damaging earthquakes).

Two computer program packages I have developed are presented in chapters in the IASPEI International Handbook of Earthquake and Engineering Seismology:

Graduate Student Research

Using an extensive data suite of surface-wave data from the Southern Africa Seismic Experiment, comparing surface-wave derived Earth-structure models for the Kaapvaal craton with seismic velocities estimated from mantle xenoliths brought to the surface in kimberlite pipes. The are effectively the same, indicating that the structure is the same now as it was 90 Ma. Also, Angela (Mouse) Larson showed in her M.S. project that there is no strong low-velocity zone beneath the Kaapvaal craton — at least to a depth of 180 km. Mouse is now a Ph.D. candidate at Penn State. Her thesis is titled “S-wave velocity structure beneath the Kaapvaal Craton from surface-wave inversions compared with estimates from mantle xenoliths.” An electronic version of her thesis is on the Virginia Tech library server. Click here to view the abstract, which in turn has a link to the full thesis as a PDF file.

A PhD student (Summer 1998), Martin Chapman, developed an alternative approach for the design earthquake problem in probabilistic seismic hazard analysis. He noted that most current ground motion prediction models are essentially independent of the earthquake duration so that a nearby magnitude 5.5 earthquake may be modeled as equivalent to a more distant magnitude 6.2 event so far as hazard potential is concerned if they have the same maximum peak ground motion at the site. Yet the failure criterion for many building materials may be affected by the duration of shaking. His modeling approach was to use the elastic input energy spectrum as an alternative to the more commonly used elastic response spectrum, and he performed a regression analysis using strong-motion data from Western North America using equivalent data-processing procedures for the two approaches. His dissertation is titled "Disaggregated Seismic Hazard and the Elastic Input Energy Spectrum: An Approach to Design Earthquake Selection." An electronic version of his dissertation is on the Virginia Tech library server. Click here to view the abstract, which in turn has a link to the full thesis as a PDF file. Martin Chapman is now a Research Assistant Professor in the Department. Click here for Chapman’s home page.

A MS student (spring 1997), Heather Student, did a seismic hazard assessment for Charleston, South Carolina. An electronic version of her thesis is on the Virginia Tech library server. Click here to view the abstract, which in turn has a link to the full thesis as a PDF file.

A PhD student (fall 1996), Shaosong Huang, tested the hypothesis that present-day observations (seismicity, topography, heat flow, etc.) in northeastern and southwestern Honshu, Japan, can be explained by deterministic modeling based on rheology and on tectonic forces acting over millions of years. An important result of his work is that the observed gravity, topography and surface seismicity also constrain the intraplate coupling. This result may have important implications on whether the lack of great earthquakes in a given region is caused by a very long return cycle or the lack of seismogenic potential because of weak coupling. An electronic version of his dissertation (ETD) is on the Virginia Tech library server. Click here to view the abstract, which in turn has a link to the full dissertation as a PDF file.

Two PhD projects I supervised were in seismic source studies for data suites of Japanese earthquakes recorded on broadband seismographs. Topics included scaling relations, frequency-occurrence relations, and a possible precursor for a magnitude 7 event. An MS project was a comparative study of portable broadband sensors in terms of their applicability for studies of long-period signals at temporary sites in different geological settings. Another MS project was an in-depth study of the geometry of the Nazca plate subducting under Peru as constrained by earthquakes located by a local network. Click here to view the abstract, which in turn has a link to the full thesis as a PDF file.

Last updated: 7 May 2008