A5021629869- earthquake and tectonic studies
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Earthquake Detection and Analysis
- Seismology and Earthquake Studies
- Seismic Imaging and Inversion Techniques
- Seismic Waves and Analysis
- Hydraulic Fracturing and Reservoir Analysis
- Resilience and Mental Health
- Seismic Performance and Analysis
- thermodynamics and calorimetric analyses
- Global Energy and Sustainability Research
- Drilling and Well Engineering
- Aeolian processes and effects
- Geotechnical Engineering and Underground Structures
- Geological Modeling and Analysis
- Synthetic Aperture Radar (SAR) Applications and Techniques
- Geophysics and Gravity Measurements
- Landslides and related hazards
- GNSS positioning and interference
- Geochemistry and Geologic Mapping
- Image Processing and 3D Reconstruction
- Service-Oriented Architecture and Web Services
- Fault Detection and Control Systems
- Mechanical stress and fatigue analysis
Society of Exploration Geophysicists
2022
Independent Sector
2013
United States Geological Survey
2013
University of British Columbia
2003-2012
Massachusetts Institute of Technology
2001-2002
The US National Seismic Hazard Model (NSHM) was updated in 2023 for all 50 states using new science on seismicity, fault ruptures, ground motions, and probabilistic techniques to produce a standard of practice public policy other engineering applications (defined return periods greater than ∼475 or less ∼10,000 years). Changes time-independent seismic hazard (both increases decreases compared previous NSHMs) are substantial because the model considers more data earthquake rupture forecasts...
We have developed dynamic finite-element models of Izmit earthquake postseismic deformation to evaluate whether this is better explained by afterslip (via either velocity-strengthening frictional slip or linear viscous creep) distributed viscoelastic relaxation the lower crust. find that driven coseismic shear stress loading can reproduce time-dependent Global Positioning System data than creep on a vertical zone below rupture crustal relaxation. Our best model fits main features inversions,...
We have modeled postseismic deformation from 1999 to 2003 in the region surrounding Izmit and Düzce earthquake ruptures, using a three‐dimensional viscoelastic finite element method. Our models confirm earlier findings that surface within first few months of is principally due stable frictional afterslip on below rupture. A second process required, however, fit after several months. Viscoelastic relaxation lower crust and/or upper mantle with viscosity order 2 5 × 10 19 Pa s improves models'...
ABSTRACT We present the 2023 U.S. Geological Survey time-independent earthquake rupture forecast for conterminous United States, which gives authoritative estimates of magnitude, location, and time-averaged frequency potentially damaging earthquakes throughout region. In addition to updating virtually all model components, a major focus has been provide better representation epistemic uncertainties. For example, we have improved multifault ruptures, both in terms allowing more less fault...
We report the results of nearly 7 years postseismic deformation measurements using continuously recorded and survey mode GPS observations for 1999 Izmit‐Düzce earthquake sequence. Resolvable, time‐dependent changes to preearthquake interseismic velocity field extend at least as far continuous station in Ankara, ∼200 km southeast Izmit rupture. Seven after sequence, relative across North Anatolian Fault (NAF) reaches ∼10–12 mm/a, roughly 50% steady state rate, with highest velocities within...
The nature and distribution of low frequency earthquakes (LFEs) in subduction zones provide insight into plate boundary deformation downdip the locked seismogenic zone. We employ network autocorrelation detection to identify LFE families beneath southern Vancouver Island environs. An initial suite 5775 LFEs detected 2004 2005 at a select set 7 stations is grouped 140 using waveform cluster analysis. These are used as templates within an iterative cross correlation scheme detect across...
We investigate the effect of depth-dependent elasticity on slip inversions and coseismic stress change estimates for large strike-slip earthquakes, using a series hypothetical models 1999 Izmit, Turkey earthquake as examples. Slip are performed both semianalytical finite-element solutions surface displacements due to shear dislocation in layered uniform elastic Earth models. find that incorporating realistic increases modulus ( μ ) with depth our recovered centroid seismic potency relative...
In this study, we investigate the extent to which viscoelastic velocity perturbations (or “ghost transients”) from individual fault segments can affect elastic block model‐based inferences of slip rates GPS fields. We focus on southern California field, exploring effects known, large earthquakes for two end‐member rheological structures. Our approach is compute, at each site, perturbation relative a cycle average earthquake cycles particular segments. then correct SCEC CMM4.0 field and...
Abstract This report describes geodetic and geologic information used to constrain deformation models of the 2023 update National Seismic Hazard Model (NSHM), a set interpret these data, their implications for earthquake rates in western United States. Recent updates provide much larger data Global Positioning System crustal velocities than 2014 NSHM, as well hundreds new faults considered active sources NSHM. These are interpreted by four that estimate fault slip uncertainties together with...
This paper describes differences in time-varying post-seismic deformation due to after-slip and viscoelastic relaxation following large strike-slip earthquakes, how these may be exploited characterize the configuration rheology of aseismically deforming material subsurface. The analysis involves two steps. First, near-field, time-dependent characteristics a typical Mw= 7.4 earthquake is defined based on GPS data from three recent earthquakes. Secondly, this modelled (assuming uniform slip...
Abstract Seismic cycle models of the northern and southern San Andreas fault (SAF) were developed to estimate corrections for viscoelastic transients embedded in present-day Global Positioning System (GPS) velocity field. These incorporate a viscous shear zone either layered or 3D structure. In SAF model, effective viscosity structure is based on Southern California Earthquake Center (SCEC) community rheology model (CRM) SCEC thermal model. Viscoelastic materials are represented with Burgers...
Abstract We have developed a suite of earthquake cycle models for strike‐slip faults to investigate how finite ruptures and lithosphere‐scale viscous shear zones affect interseismic deformation. In particular, we assess whether localized stationary deformation large‐scale, rapidly decaying postseismic transients may be explained with incorporating either or both these features. Models give more than layered half‐space, Maxwell viscoelastic producing similar early in the near field. This...
Abstract We have developed groundwater flow models to explore the possible relationship between wastewater injection and 12 November 2014 M w 4.8 Milan, Kansas earthquake. calculate pore pressure increases in uppermost crust using a suite of which hydraulic properties Arbuckle Formation Milan earthquake fault zone, hypocenter depth, zone geometry are varied. Given pre‐earthquake volumes reasonable hydrogeologic properties, significantly increasing at requires that most occur through...
Deformation in the southern Walker Lane Belt region of southwestern Great Basin accommodates significant portions both Pacific‐North America transform motion and Range extension. Apparent kinematic inconsistencies between geodetic fault slip data this have made it difficult to understand nature interaction these deformation processes infer regional kinematics. We model kinematics a manner that enforces consistency includes geometry rate data, Global Positioning System (GPS) survey very long...
Numerical simulations of long-term crustal deformation reveal the important role that damage healing (i.e. fault-zone strengthening) plays in structural evolution strike-slip fault systems. We explore sensitivity simulated zone structure and patterns to reasonable variations healing-rate parameters a continuum rheology model. Healing effectiveness, defined herein as function rate parameters, describes post-seismic process terms characteristic inter-seismic level expected along segments our...
Geodetic and seismic observations reveal long‐lived zones with reduced elastic moduli along active crustal faults. These fault localize strain from nearby earthquakes, consistent the response of a compliant, layer. Fault zone trapped wave studies documented small reduction in P S velocities Johnson Valley caused by 1999 Hector Mine earthquake. This presumably perturbed permanent compliant structure associated fault. The inferred changes compliance may produce measurable deformation to...
We have modeled linear viscoelastic relaxation of a uniform‐viscosity asthenosphere following large earthquakes in the Aegean‐Anatolian region during 20th century to evaluate whether this process contributes significantly regional velocity field. address particular southward motion Aegean Sea relative central Anatolia (and thus extension western Turkey) can be attributed postseismic strain pulse. Our models show that thick (250 km) substrate cannot generate observed Turkey, regardless choice...
The 1991, M s = 7.0 Racha earthquake is the largest ever recorded in Caucasus Mountains. Approximately three months after this thrust‐faulting earthquake, a GPS network was set up to measure postseismic surface deformation. We present an analysis of these data, which indicate accelerated motions at several near‐field sites. model deformation as either afterslip on rupture or viscoelastic relaxation lower crust. find that are best explained by shallow plane. minimum moment release estimated...
Abstract Geodetic studies have shown that deformation rates around several major strike‐slip faults are asymmetric. This asymmetry is often explained in terms of a crustal‐scale contrast elastic properties across the fault. Motivated by fact elasticity variations for different rock types under similar ambient conditions generally modest, whereas effective viscosity may vary over orders magnitude, we developed earthquake‐cycle models to evaluate whether contrasts structure and plate thickness...
A workshop was held to begin scientific consideration of how incorporate space geodetic constraints on strain rates and fault slip into the next generation Uniform California Earthquake Rupture Forecast, version 3 (UCERF3), due be completed in mid‐2012. Principal outcomes meeting were (1) an assessment secure science ready for UCERF3 applications within year, (2) agenda new research objectives Southern Center (SCEC), U.S. Geological Survey (USGS), others support related probabilistic seismic...
Olivine and orthopyroxene crystals composing the oceanic upper mantle align under progressive simple shear strain. Because thermal diffusivities (κ) viscosities of these minerals are anisotropic, mineral alignment affects vertical heat flow dynamics. The diffusivity peridotite decreases with strain, leading to higher temperatures in shallow than predicted by an isotropic half‐space cooling model. This, turn, causes surface flow, shallower ocean basins, weaker asthenosphere, slightly thinner...