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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...
Authors
Joan S. Gomberg, D.C. Agnew, S.Y. Schwartz

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...
Authors
Ertugrul Taciroglu, Mehmet Çelebi, S. Farid Ghahari, Fariba Abazarsa

Records of continental slope sediment flow morphodynamic responses to gradient and active faulting from integrated AUV and ROV data, offshore Palos Verdes, southern California Borderland

Variations in seabed gradient are widely acknowledged to influence deep-water deposition, but are often difficult to measure in sufficient detail from both modern and ancient examples. On the continental slope offshore Los Angeles, California, autonomous underwater vehicle, remotely operated vehicle, and shipboard methods were used to collect a dense grid of high-resolution multibeam...
Authors
Katherine L. Maier, Daniel S. Brothers, Charles K. Paull, Mary McGann, David W. Caress, James E. Conrad

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...
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...
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...
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...
Authors
Andrew J. Barbour, Eileen Evans, Stephen H. Hickman, Mariana Eneva

Improved geomagnetic referencing in the Arctic environment

Geomagnetic referencing uses the Earth’s magnetic field to determine accurate wellbore positioning essential for success in today's complex drilling programs, either as an alternative or a complement to north-seeking gyroscopic referencing. However, fluctuations in the geomagnetic field, especially at high latitudes, make the application of geomagnetic referencing in those areas more...
Authors
B. Poedjono, N. Beck, A. C. Buchanan, L. Borri, S. Maus, Carol Finn, E. William Worthington, Tim White

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...
Authors
Kishor S. Jaiswal, Mark D. Petersen, Stephen Harmsen, Gregory M. Smoczyk

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...
Authors
Nico Luco, Charles A. Kircher, C. B. Crouse, Finley Charney, Curt B. Haselton, Jack W. Baker, Reid Zimmerman, John D. Hooper, William McVitty, Andy Taylor

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...
Authors
Ivan G. Wong, William R. Lund, Christopher DuRoss, Patricia Thomas, Walter Arabasz, Anthony J. Crone, Michael D. Hylland, Nico Luco, Susan S. Olig, James C. Pechmann, Stephen Personius, Mark D. Petersen, David P. Schwartz, Robert B. Smith, Steve Rowman
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