Publications
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Pseudotachylyte increases the post-slip strength of faults
Solidified frictional melts, or pseudotachylytes, are observed in exhumed faults from across the seismogenic zone. These unique fault rocks, and many experimental studies, suggest that frictional melting can be an important process during earthquakes. However, it remains unknown how melting affects the post-slip strength of the fault and why many exhumed faults do not contain pseudotachylyte. Anal
Authors
Brooks P. Proctor, David A. Lockner
2016 update on induced earthquakes in the United States
During the past decade people living in numerous locations across the central U.S. experienced many more small to moderate sized earthquakes than ever before. This earthquake activity began increasing about 2009 and peaked during 2015 and into early 2016. For example, prior to 2009 Oklahoma typically experienced 1 or 2 small earthquakes per year with magnitude greater than 3.0 but by 2015 this nu
Authors
Mark D. Petersen
Alternative source models of very low frequency events
We present alternative source models for very low frequency (VLF) events, previously inferred to be radiation from individual slow earthquakes that partly fill the period range between slow slip events lasting thousands of seconds and low-frequency earthquakes (LFE) with durations of tenths of a second. We show that VLF events may emerge from bandpass filtering a sum of clustered, shorter duration
Authors
Joan S. Gomberg, D.C. Agnew, S.Y. Schwartz
Earthquake ground motion
Most of the effort in seismic design of buildings and other structures is focused on structural design. This chapter addresses another key aspect of the design process—characterization of earthquake ground motion into parameters for use in design. Section 3.1 describes the basis of the earthquake ground motion maps in the Provisions and in ASCE 7 (the Standard). Section 3.2 has examples for the de
Authors
Nicolas Luco, Charles A. Kircher, C. B. Crouse, Finley Charney, Curt B. Haselton, Jack W. Baker, Reid Zimmerman, John D. Hooper, William McVitty, Andy Taylor
An investigation of soil-structure interaction effects observed at the MIT Green Building
The soil-foundation impedance function of the MIT Green Building is identified from its response signals recorded during an earthquake. Estimation of foundation impedance functions from seismic response signals is a challenging task, because: (1) the foundation input motions (FIMs) are not directly measurable, (2) the as-built properties of the super-structure are only approximately known, and (3)
Authors
Ertugrul Taciroglu, Mehmet Çelebi, S. Farid Ghahari, Fariba Abazarsa
Helium as a tracer for fluids released from Juan de Fuca lithosphere beneath the Cascadia forearc
The ratio between helium isotopes (3He/4He) provides an excellent geochemical tracer for investigating the sources of fluids sampled at the Earth's surface. 3He/4He values observed in 25 mineral springs and wells above the Cascadia forearc document a significant component of mantle-derived helium above Juan de Fuca lithosphere, as well as variability in 3He enrichment across the forearc. Sample si
Authors
Patricia A. McCrory, James E. Constantz, Andrew G. Hunt, J. Luke Blair
PhasePApy: A robust pure Python package for automatic identification of seismic phases
We developed a Python phase identification package: the PhasePApy for earthquake data processing and near‐real‐time monitoring. The package takes advantage of the growing number of Python libraries including Obspy. All the data formats supported by Obspy can be supported within the PhasePApy. The PhasePApy has two subpackages: the PhasePicker and the Associator, aiming to identify phase arrival on
Authors
Chen Chen, Austin Holland
Terrestrial cosmogenic surface exposure dating of glacial and associated landforms in the Ruby Mountains-East Humboldt Range of central Nevada and along the northeastern flank of the Sierra Nevada
Deposits near Lamoille in the Ruby Mountains-East Humboldt Range of central Nevada and at Woodfords on the eastern edge of the Sierra Nevada each record two distinct glacial advances. We compare independent assessments of terrestrial cosmogenic nuclide (TCN) surface exposure ages for glacial deposits that we have determined to those obtained by others at the two sites. At each site, TCN ages of bo
Authors
Steven G. Wesnousky, Richard W. Briggs, Marc W. Caffee, Rick J. Ryerson, Robert C. Finkel, Lewis A. Owen
Sources of subsidence at the Salton Sea Geothermal Field
At the Salton Sea Geothermal Field (SSGF) in Southern California, surface deformation associated with geologic processes including sediment compaction, tectonic strain, and fault slip may be augmented by energy production activities. Separating the relative contributions from natural and anthropogenic sources is especially important at the SSGF, which sits at the apex of a complex tectonic transit
Authors
Andrew J. Barbour, Eileen Evans, Stephen H. Hickman, Mariana Eneva
Earthquake probabilities for the Wasatch front region in Utah, Idaho, and Wyoming
In a letter to The Salt Lake Daily Tribune in September 1883, U.S. Geological Survey (USGS) geologist G.K. Gilbert warned local residents about the implications of observable fault scarps along the western base of the Wasatch Range. The scarps were evidence that large surface-rupturing earthquakes had occurred in the past and more would likely occur in the future. The main actor in this drama is t
Authors
Ivan G. Wong, William R. Lund, Christopher DuRoss, Patricia Thomas, Walter Arabasz, Anthony J. Crone, Michael D. Hylland, Nicolas Luco, Susan S. Olig, James C. Pechmann, Stephen Personius, Mark D. Petersen, David P. Schwartz, Robert B. Smith, Steve Rowman
Assessing the seismic risk potential of South America
We present here a simplified approach to quantifying regional seismic risk. The seismic risk for a given region can be inferred in terms of average annual loss (AAL) that represents long-term value of earthquake losses in any one year caused from a long-term seismic hazard. The AAL are commonly measured in the form of earthquake shaking-induced deaths, direct economic impacts or indirect losses ca
Authors
Kishor S. Jaiswal, Mark D. Petersen, Stephen Harmsen, Gregory M. Smoczyk
Assessing the geologic and climatic forcing of biodiversity and evolution surrounding the Gulf of California
For almost a century the Baja California peninsula (Peninsula), Gulf of California (Gulf), and broader Sonoran Desert region (figure 1) have drawn geologists and biologists alike to study its unique physical and evolutionary processes (e.g., Wittich 1920; Darton 1921; Nelson 1921; Johnston 1924; Beal 1948; Durham and Allison 1960). The challenge remains to untangle the long, intricate, and at time
Authors
Greer Dolby, Scott E. K. Bennett, Andres Lira-Noriega, Benjamin T. Wilder, Adrian Munguia-Vega