Devin F McPhillips

Updated Compilation of VS30 Data for the United States

VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30 data are sparse or not readily available for most areas. Where data are available, VS30 values are often assembled in assorted formats that are accessible from disparate and (or) impermanent Websites. To help remedy this situation, we compiled VS30 measurements obtained by studies funded by the U.S. Geological Survey (USGS) and...

Categories: Data; Tags: Geophysics, Seismology, USGS Science Data Catalog (SDC), United States, earthquake seismology, All tags... seismic hazard maps, seismic monitoring stations, seismic profiles, Fewer tags

High-resolution seismic data acquired at six Southern California Seismic Network (SCSN) recording stations in 2017

In August 2017, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data near six Southern California Seismic Network (SCSN) recording stations in southern California: CI.OLI Olinda; CI.SRN Serrano; CI.MUR Murrieta; CI.LCG La Cienega; CI.RUS Rush; and CI.STC Santa Clara (Figure 1). These strong-motion recording stations are located inside Southern California Edison electrical substations, critical infrastructures that provide essential services to millions of customers. The primary goals of the seismic survey were to understand the potential for amplified ground shaking and to evaluate lateral variability in shear-wave velocity at these sites. We deployed up to 88 geophones at 2-m or 4-m...

Categories: Data; Types: Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: Geophysics, Seismology, Shear-wave velocity, Southern California, USGS Science Data Catalog (SDC), All tags... earthquake hazards, ground motion, seismic refraction methods, seismology, shaking, site characterization, surface wave method, Fewer tags

Sediment properties, charcoal counts, and radiocarbon dates from the Pallett Creek paleoseismic site, San Gabriel Mountains, California (ver. 2.0, February 2024)

This data release provides geochemical, sedimentological, and geochronological data from interbedded fluvial and marsh deposits and radiocarbon dates of the section spanning the last 1500 years from the Pallett Creek paleoseismic site, California. The samples were collected to support paleoenvironmental reconstruction of the site and refine several previous investigations of paleoearthquakes along the San Andreas Fault (Sieh, 1978; Sieh, 1984; Sieh et al., 1989; Biasi and Weldon, 1994; Scharer et al., 2011). Geochemical and sedimentological data include grain size, magnetic susceptibility, dry bulk density, percent total organic matter, and percent total carbonate at contiguous 1 cm spacing and carbon (total C)...

Categories: Data, Data Release - Revised; Types: Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: Geomorphology, Seismology, Stratigraphy, USGS Science Data Catalog (SDC), carbon-14 analysis, All tags... climate change, geoscientificInformation, sedimentology, Fewer tags

Radiocarbon dates from the 2020 Bobcat Fire and 2013 Grand Fire, Western Transverse Ranges, California

This data release provides radiocarbon data for burned plant material collected from deposits following two wildfires in southern California. For the 2020 Bobcat Fire we collected deposits in five stream channels within the Pallett Creek drainage in 2021. For the 2013 Grand Fire near Frazier Mountain, we sampled from two shallow pits excavated into alluvium deposited in 2014. The types of taxa present at each sample location were identified and radiocarbon samples were selected based on the types of material present. This report should be used as the supplementary materials for any publication(s) that uses the radiocarbon dates or taxa identification reported herein.

Categories: Data; Tags: Forestry, Frazier Mountain, Geomorphology, Pallett Creek, San Gabriel Mountains, All tags... Seismology, USGS Science Data Catalog (SDC), carbon-14 analysis, fires, geochronology, geoscientificInformation, wildfire, Fewer tags

Precariously balanced rock data from northern New York and Vermont, USA

This work describes observations of boulders and their pedestals at five sites in New York and Vermont, which are used to calculate scaling factors for the 2023 time-independent National Seismic Hazard Model site-specific hazard curves (Petersen, M.D., Shumway, A.M., Powers, P.M., Field, E.H., Moschetti, M.P., Jaiswal, K.S., Milner, K.R., Rezaeian, S., Frankel, A.D., Llenos, A.L. and Michael, A.J., 2024. The 2023 US 50-State National Seismic Hazard Model: Overview and implications. Earthquake Spectra, 40(1), pp.5-88). This approach represents the current best-practice for validating hazard curves using precariously balanced rocks (e.g., Rood, A.H., Rood, D.H., Stirling, M.W., Madugo, C.M., Abrahamson, N.A., Wilcken,...

Categories: Data; Tags: Geomorphology, Geophysics, Lake Champlain, New York, Seismology, All tags... USGS Science Data Catalog (SDC), Vermont, earthquake occurrences, geomorphology, seismology, Fewer tags