A5032445464- earthquake and tectonic studies
- GNSS positioning and interference
- Seismology and Earthquake Studies
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Seismic Waves and Analysis
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Inertial Sensor and Navigation
- Seismic Imaging and Inversion Techniques
- Advanced Computational Techniques and Applications
- Astronomical Observations and Instrumentation
- Geological and Geophysical Studies
- Fault Detection and Control Systems
- Advanced Frequency and Time Standards
- Indoor and Outdoor Localization Technologies
- Time Series Analysis and Forecasting
- Soil Moisture and Remote Sensing
- Hydrocarbon exploration and reservoir analysis
- Geochemistry and Geologic Mapping
- Geophysics and Sensor Technology
- IoT and GPS-based Vehicle Safety Systems
- Meteorological Phenomena and Simulations
- Synthesis and Properties of Aromatic Compounds
- Disaster Response and Management
Central Washington University
2014-2025
Charles River Laboratories (Netherlands)
2016
California Institute of Technology
1995-1998
Abstract The Geodesy Advancing Geosciences and EarthScope (GAGE) Facility Global Positioning System (GPS) Data Analysis Centers produce position time series, velocities, other parameters for approximately 2000 continuously operating GPS receivers spanning a quadrant of Earth's surface encompassing the high Arctic, North America, Caribbean. purpose this review is to document methodology generating station positions their evolution over describe requisite trade‐offs involved with combination...
Continuous geodetic measurements from convergent margins have shown that deep transient creep events can release large amounts of strain energy without detectable seismic shaking, and they are thus known as slow or silent earthquakes. Because subduction zones generate the largest earthquakes,
Automatically detected and located tremor epicenters from episodic slip (ETS) episodes in northern Cascadia provide a high‐resolution map of Washington's slow region. Thousands the past four ETS events 2004 to 2008 detailed map‐view constraints that correlate with geodetic estimates simultaneous slip. Each these exhibits remarkable similarity timing geographic distribution density geodetically inferred Analysis latest 15‐month inter‐ETS period also reveals ageodetic activity similar both...
Research Article| June 08, 2016 Demonstration of the Cascadia G‐FAST Geodetic Earthquake Early Warning System for Nisqually, Washington, Brendan W. Crowell; Crowell aDepartment Earth and Space Sciences, University Johnson Hall Room‐070, Box 351310, 4000 15th Avenue NE, Seattle, Washington 98195‐1310 U.S.A.crowellb@uw.edu Search other works by this author on: GSW Google Scholar David A. Schmidt; Schmidt Paul Bodin; Bodin John E. Vidale; Vidale Joan Gomberg; Gomberg bU.S. Geological Survey,...
We describe the detection of teleseismic surface waves from 3 November 2002 Mw 7.9 Denali fault earthquake in Alaska with a dense network 1 Hz GPS stations southern California, about 3900 km event. Relative horizontal displacements amplitudes excess 15 mm and duration 700 seconds agree integrated velocities recorded by nearby broadband seismometers an rms difference 2–3 mm. The are derived independent instantaneous positions demonstrating that can provide direct measurements arbitrarily...
Refinements to GPS analyses in which we factor geodetic time series better estimate both reference frames and transient deformation resolve 34 slow slip events located throughout the Cascadia subduction zone from 1997 through 2005. Timing of onset is determined with wavelet transformation series. Thirty continuous stations are included this study, ranging northern California southwestern British Columbia. Our improvements analysis largest creep also identify many smaller events. At 48.5°N...
A comparison of GPS and seismic analyses 23 distinct episodic tremor slip events, located throughout the Cascadia subduction zone over an 11‐year period, yields a highly linear relationship between moment release, as estimated from GPS, total duration nonvolcanic tremor, summed regional arrays. The events last 1–5 weeks, typically produce ∼5 mm static forearc deformation, show cumulative totals that range 40 to 280 h. Moment released by each event is inverting GPS‐measured which sensitive...
Abstract Traditional real-time (RT) seismology has relied on inertial sensors to characterize ground motions and earthquake sources, particularly for hazards applications such as warning systems. In the past decade, a revolution in high-rate, RT Global Navigation Satellite Systems (GNSS) displacement provided new source of data augment traditional measurement devices. The Ridgecrest, California, sequence 2019 one most complete recordings RT-GNSS displacements date, helping aid an initial...
Continuous GPS time series from three of four recently measured, large subduction earthquakes document triggered rapid postseismic fault creep, representing an additional moment release upward 25% over the weeks following their main shocks. Data two M w = 8.0 and 8.4 events constrain centroids to lie down dip lower limit coseismic faulting, show that afterslip along primary asperities is significantly less important than deep creep. Time for another 7.7 event 30% energy release, but here we...
Abstract We construct coastal Pacific Northwest profiles of vertical land motion (VLM) known to bias long‐term tide‐gauge measurements sea‐level rise (SLR) and use them estimate absolute with respect Earth's center mass. Multidecade GPS at 47 stations along the Cascadia subduction zone show VLM varies regionally but smoothly coast inland Puget Sound rates ranging from + 4.9 −1.2 mm/yr. is characterized by uniform subsidence relatively slow −0.1 −0.3 Uplift 4.5 mm/yr persist western Olympic...
Research Article| October 03, 2018 Development of a Geodetic Component for the U.S. West Coast Earthquake Early Warning System J. R. Murray; Murray aU.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025 U.S.A., jrmurray@usgs.gov Search other works by this author on: GSW Google Scholar B. W. Crowell; Crowell bDepartment Earth and Space Sciences, University Washington, Johnson Hall Room‐070, Box 351310, 4000 15th Avenue NE, Seattle, Washington 98195 U.S.A....
Continuous GPS and seismic data from northern California show that slow earthquakes periodically rupture the Gorda‐North America plate interface within southern Cascadia. On average, these creep events have occurred every 10.9 ± 1.2 months since at least 1998. Appearing as week‐long extensional transients reverse secular forearc contraction, a recurrence interval 22% shorter than recognized to north. Seismic tremor here accompanies reversals, correlated across many 5 seismometers. Tremor...
A suite of 15 episodic tremor and slip events imaged between 1997 2008 along the northern Cascadia subduction zone suggests future coseismic rupture will extend to 25 km depth, or ∼60 inland Pacific coast, rather than stopping offshore at depth. An ETS‐derived coupling profile accurately predicts GPS‐measured interseismic deformation overlying North American plate, as measured by ∼50 continuous GPS stations across western Washington State. When extrapolated over 550‐year average recurrence...
The noise in position time series of 568 GPS (Global Position System) stations across North America with an observation span ten years has been investigated using solutions from two processing centers, namely, the Pacific Northwest Geodetic Array (PANGA) and New Mexico Tech (NMT). It is well known that frequency domain, exhibits a power-law behavior spectral index around −1. By fitting various models to observations selecting most likely one, we demonstrate some regions flattens zero at long...
Inversion of continuous GPS measurements from the Pacific Northwest show 2003 Cascadia slow earthquake to be among largest ten transients recognized here. Twelve stations bracketing slip indicate transient propagated bi‐directionally initiation in southern Puget basin, reaching 300 km along‐strike over a period seven weeks. This event produced, for first time, resolvable vertical subsidence, and horizontal displacement six mm Washington State. Inverted non‐negative thrust slip, maximum 3.8...
Abstract Large earthquakes are difficult to model in real‐time with traditional inertial seismic measurements. Several algorithms that leverage high‐rate Global Navigation Satellite Systems (HR‐GNSS) positions have been proposed, and it has shown they can supplement the earthquake monitoring effort. However, analyses of long‐term noise behavior GNSS positions, which important understand how data be used operationally by agencies, limited just a few sites short time spans. Here, we show...
Previous studies have estimated the sea level rise (SLR) at various locations on west coast of USA and Vancouver Island in Canada. Here, we construct an entire SLR profile from Pacific Northwest to San Diego Southern California. First, process global navigation satellite system (GNSS) measurements 405 stations blanketing whole generate a vertical land motion (VLM) known bias century-long tide gauge (TG) recording relative (RSLR). We are then able estimate absolute (ASLR) by correcting with...
The October, 1995 Mw 8.0 Jalisco subduction earthquake has provided a thorough geodetic observation of the coseismic process. An 11 station regional GPS network located directly onshore rupture demonstrates consistent vertical subsidence verified by tide gauge data and southwest‐directed extension, with measured displacements reaching 1 meter. Unusually shallow non‐uniform faulting is required to explain displacements. We determine that up 5 meters slip occurred within upper 15 km thrust...
Abstract Regional networks of Global Navigation Satellite System (GNSS) stations cover seismically and volcanically active areas throughout the United States. Data from these have been used to produce high-precision, three-component velocity fields covering broad geographic regions as well position time series that track time-varying crustal deformation. This information has contributed assessing interseismic strain accumulation related seismic hazard, revealed previously unknown occurrences...
ABSTRACT The ShakeAlert earthquake early warning (EEW) system partners along with U.S. Geological Survey (USGS) licensed operators deliver EEW alerts to the public and trigger automated systems when a significant is expected impact California, Oregon, or Washington. ShakeAlert’s primary goal provide usable times before arrival of damaging shaking. most likely achieve this in large-magnitude earthquakes. In recent years, has gone through series upgrades its underlying scientific algorithms...
Two‐hour position estimates from a continuous GPS station located at Arequipa, Peru, document precursory deformation beginning 18 hours prior to an M w = 7.6 aftershock of the June 23rd 2001 8.4 earthquake. This preseismic signal appears on north and east components as slow displacement with amplitude twice that subsequent coseismic. Analysis three years 18‐hour rate measurement shows this be unprecedented beyond four standard deviations mean rate. The best fitting centroid is directionally...
The April 14, 1995, earthquake in western Texas ( M w 5.7) produced a strong topside reflection off the 410‐km discontinuity which was recorded on multitude of seismic arrays throughout southwestern United States. Data from 394 vertical short‐period and 24 broadband instruments provide dense coverage this event distances 11° to 19° detailed look at subcontinental structure. salient features data set are (1) dependence wavelength triplication range, (2) uniform amplitude ratio direct P...
We model broadband seismograms containing triplicated S , 2 and 3 along with ScS to produce a pure path one‐dimensional extending from the crust core‐mantle boundary beneath East Pacific Rise. simultaneously all body wave shapes amplitudes, thereby eliminating depth‐velocity ambiguities. The data consist of western North American recordings Rise (EPR) affiliate transform events that form continuous record section out 82° sample nearly entire best fitting synthetics contain attenuation small...
The seismic wavefield propagating along the recently instrumented Pacific‐North American plate boundary (California) displays remarkable variation, with regional shear waves arriving at coastal stations up to 20 seconds earlier than equidistant in eastern California. Broadband modeling of this data reveals that paths sample fast upper mantle typical Miocene‐aged ocean (>50 Km thickness). Inland slower uppermost mantle, lithosphere, or lid, measuring less 5 thick, characteristic Basin and...