A5029033878- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Seismology and Earthquake Studies
- earthquake and tectonic studies
- High-pressure geophysics and materials
- Geophysics and Sensor Technology
- Geophysical Methods and Applications
- Geological and Geochemical Analysis
- Underwater Acoustics Research
- Earthquake Detection and Analysis
- Geological Studies and Exploration
- Methane Hydrates and Related Phenomena
- Hydrocarbon exploration and reservoir analysis
- Noise Effects and Management
- Geophysical and Geoelectrical Methods
- Geological Modeling and Analysis
- Drilling and Well Engineering
- Geological and Geophysical Studies
- Ultrasonics and Acoustic Wave Propagation
- Geophysics and Gravity Measurements
- Acoustic Wave Phenomena Research
- Geology and Paleoclimatology Research
- Speech and Audio Processing
- Mechanical and Optical Resonators
- Structural Health Monitoring Techniques
University of Utah
2016-2025
Institute of Earth Sciences, Academia Sinica
2019-2021
National Tsing Hua University
2018
Georgia Institute of Technology
2017
California Institute of Technology
2012-2013
University of Colorado Boulder
2006-2011
University of Colorado System
2007
Drexel University
2004-2006
Southeast University
1989
Ambient noise tomography is a rapidly emerging field of seismological research. This paper presents the current status ambient data processing as it has developed over past several years and intended to explain justify this development through salient examples. The procedure divides into four principal phases: (1) single station preparation, (2) cross-correlation temporal stacking, (3) measurement dispersion curves (performed with frequency—time analysis for both group phase speeds) (4)...
We present the results of Rayleigh wave and Love phase velocity tomography in western United States using ambient seismic noise observed at over 250 broad-band stations from EarthScope/USArray Transportable Array regional networks. All available three-component time-series for 12-month span between 2005 November 1 2006 October 31 have been cross-correlated to yield estimated empirical Green's functions. The signals were with higher average signal-to-noise ratio (SNR) than hence cannot be...
Ambient noise tomography has proven to be effective in resolving shallow earth structure. We applied ambient on a dense seismic array Long Beach, California. The was composed of more than 5200 stations with an average spacing close 100 m. Three weeks passive were crosscorrelated between each station pair, which resulted 13.5 million crosscorrelations within the area. Clear fundamental-mode Rayleigh waves observed 0.5 and 4 Hz, most sensitive structure above 1-km depth. For we frequency-time...
We present a new method of surface wave tomography based on applying the eikonal equation to observed phase traveltime surfaces computed from seismic ambient noise. The source—receiver reciprocity in noise implies that each station can be considered an effective source and between all other stations is used track front construct surface. Assuming amplitude waveform varies smoothly, states gradient estimate both local speed direction propagation. For location, we statistically summarize...
Using data from more than 2000 seismic stations multiple networks arrayed throughout China (CEArray, Array, NECESS, PASSCAL, GSN) and surrounding regions (Korean Seismic Network, F-Net, KNET), we perform ambient noise Rayleigh wave tomography across the entire region earthquake parts of South Northeast China. We produce isotropic group phase speed maps with uncertainty estimates 8 to 50 s period study, extend them 70 where is performed. Maps azimuthal anisotropy are estimated simultaneously...
We present the first New Zealand-wide study of surface wave dispersion, using ambient noise observed at 42 broad-band stations in national seismic network (GeoNet) and Global Seismic Network (GSN). Year-long vertical-component time-series recorded between 2005 April 1 2006 March 31 have been correlated with one another to yield estimated fundamental mode Rayleigh Green's functions. filter these functions compute group dispersion curves periods 5–50 s, a phase-matched filter, frequency-time...
The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in world. An understanding its properties key to enhancing our knowledge mechanisms and corresponding risk. Using a joint local teleseismic earthquake P-wave seismic inversion, we revealed basaltic lower-crustal magma body that provides magmatic link between mantle plume previously imaged upper-crustal reservoir. This has volume 46,000 cubic kilometers, ~4.5 times reservoir, contains melt fraction...
A non-linear Bayesian Monte-Carlo method is presented to estimate a Vsv model beneath stations by jointly interpreting Rayleigh wave dispersion and receiver functions associated uncertainties. The designed for automated application large arrays of broad-band seismometers. As testbed the method, 185 from USArray Transportable Array are used in Intermountain West, region that geologically diverse structurally complex. Ambient noise earthquake tomography updated applying eikonal Helmholtz...
Mantle seismic structure beneath the United States spanning from active western plate margin to passive eastern was imaged with teleseismic P and S wave traveltime tomography including USArray data up May 2014. To mitigate artifacts crustal 5–40 s, Rayleigh phase velocities were used create a 3-D starting model. Major features of final models include two distinct low-velocity anomalies at depths ~60–300 km central northern Appalachians margin. The Appalachian anomaly coincides Eocene...
Ambient noise tomography and multiple plane wave earthquake are new methods of surface analysis that yield much more highly refined information about the crust uppermost mantle than traditional techniques. Applied together to data observed at 300 broadband seismic stations from Transportable Array component EarthScope USArray, these dispersion curves 8 100 s period across entire western United States with unprecedented resolution. We use local Rayleigh phase speed construct a unified...
The growth of the Earthscope/USArray Transportable Array (TA) has prompted development new methods in surface wave tomography that track phase fronts across array and map traveltime field for each earthquake or station from ambient noise. Directionally dependent velocities are determined locally by measuring gradient observed without performance a formal inversion. This method is based on eikonal equation is, therefore, referred to as 'eikonal tomography'. Eikonal bent-ray theoretic method,...
Abstract Seismic structure beneath the contiguous U.S. was imaged with multimode receiver function stacking and inversion of Rayleigh wave dispersion ellipticity measurements. Crust thickness elevation are weakly correlated across U.S., but correlation is ~3–4 times greater for separate areas east west Rocky Mountain Front (RMF). Greater lower crustal shear velocities RMF, particularly in low‐elevation thick crust, consistent deep density as primary cause contrasting crust versus trends....
Rayleigh wave ellipticity, or H/V ratio, observed on the surface is particularly sensitive to shallow earth structure. In this study, we jointly invert measurements of ratio and phase velocity between 24–100 8–100 sec period, respectively, for crust upper mantle structure beneath more than 1000 USArray stations covering western United States. Upper crustal structure, in particular, better constrained by joint inversion compared inversions based velocities alone. addition imaging Vs show that...
We present a new 3-D seismic model of the western United States crust derived from joint inversion Rayleigh-wave phase velocity and ellipticity measurements using periods 8 to 100 s. Improved constraints on upper-crustal structure result use short-period ellipticity, or H/V (horizontal vertical) amplitude ratios, determined multicomponent ambient noise cross-correlations. To retain ratio information between vertical horizontal components, for each station, we perform daily pre-processing...
Abstract Seismic body waves that sample Earth's core are indispensable for studying the most remote regions of planet. Traditional phase studies rely on well‐defined earthquake signals, which spatially and temporally limited. We show that, by stacking ambient‐noise cross‐correlations between USArray seismometers, wave phases reflected off outer ( ScS ), twice refracted through inner PKIKP 2 ) can be clearly extracted. Temporal correlation amplitude these global seismicity suggests signals...
ABSTRACT Seismic tomography is the most abundant source of information about internal structure Earth at scales ranging from a few meters to thousands kilometers. It constrains properties active volcanoes, earthquake fault zones, deep reservoirs and storage sites, glaciers ice sheets, or entire globe. contributes outstanding societal problems related natural hazards, resource exploration, underground storage, many more. The recent advances in seismic are being translated nondestructive...
Surface wave dispersion measurements from ambient seismic noise and array‐based teleseismic earthquakes observed with the EarthScope/USArray Transportable Array (TA) are inverted using a Monte Carlo method for 3‐D V S model of crust uppermost mantle beneath western United States. The combination data these methods produces exceptionally broadband information 6 to 100 s period, which constrains shear velocity structures in depth more than km. high lateral resolution produced by TA network...
The deployment of USArray across the continental U.S. has prompted developments within surface wave tomography to exploit this unprecedented data set. Here, we present a method measure new observable: broadband amplification that provides and unique constraints on elastic velocities density crust upper mantle. method, similar its phase velocity counterpart referred as Helmholtz tomography, initiates by constructing travel time amplitude maps array for each period earthquake. Spatial...
Abstract We investigated upper crustal structure with data from a dense seismic array deployed around Mount St. Helens for 2 weeks in the summer of 2014. Interstation cross correlations ambient noise were obtained, and clear fundamental mode Rayleigh waves observed between 2.5 5 s periods. In addition, higher‐mode signals period. Frequency‐time analysis was applied to measure wave phase velocities, which used invert 2‐D velocity maps. An azimuth‐dependent traveltime correction implemented...
Abstract Mantle shear velocity (Vs) structure beneath the Transportable Array (TA) in Alaska and northwestern Canada is imaged by joint inversion of Rayleigh wave dispersion teleseismic S travel times. The study connects previously unsampled parts northern western with portions southern earlier seismic arrays. new Vs tomography shows contrasting lithospheric plate interior lower shallow upper mantle indicative thinner thermal lithosphere south Brooks Range along transform margin. Higher down...
Abstract Through the Alaska Transportable Array deployment of over 200 stations, we create a 3‐D tomographic model with sensitivity ranging from near surface (<1 km) into upper mantle (~140 km). We perform Markov chain Monte Carlo joint inversion Rayleigh wave ellipticity and phase velocities, both ambient noise earthquake measurements, along receiver functions to shear velocity model. also use follow‐up resolve interstation structure. By comparing our results previous tomography,...
Research Article| July 12, 2018 Seismically anisotropic magma reservoirs underlying silicic calderas Chengxin Jiang; Jiang 1Department of Earth and Planetary Sciences, The University New Mexico, Albuquerque, Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Brandon Schmandt; Schmandt Jamie Farrell; Farrell 2Department Geology Geophysics, Utah, Salt Lake City, Utah 84112, Fan-Chi Lin; Lin Kevin M. Ward Author Article Information Publisher: Geological Society...