Abstract To investigate the physical basis for support of topography in western U.S., we construct a subcontinent scale, 3‐D density model using ~1000 estimated crustal thicknesses and S velocity profiles to 150 km depth at each 947 seismic stations. Crustal temperature composition are considered, but assume that mantle variations thermal origin. From these densities, calculate topographic contributions. Typical 2σ uncertainty is ~500 m, elevations 84% region reproduced within error....

Abstract Thousands were killed by the 8 September 2023 Mw 6.8 Al Haouz, Morocco, earthquake in western High Atlas (WHA) Mountains. To identify faults and fault orientations most likely to host aftershocks future large earthquakes, regional crustal stress is estimated from focal mechanism inversions, associated slip potential of known suspected active modeled. North–south shortening accommodated a mix reverse, oblique-reverse, strike-slip motion. As such, many are well aligned for slip: steep...

Abstract Earthquakes far from tectonic plate boundaries generally exploit ancient faults, but not all intraplate faults are equally active. The North American Great Plains exemplify such earthquake localization, with both natural and induced seismicity clustered in discrete zones. Here we use seismic velocity, gravity topography to generate a 3D lithospheric density model of the region; subsequent finite-element modelling shows that focuses regions high-gravity-derived deviatoric stress....

Abstract Topography can be directly observed, but what controls topographic variation is not readily known. To investigate a prominent and remarkably consistent along‐trend gradient belt (TGB) in intraplate eastern China its connection to ongoing deformation geodynamics, we examine the regional density structure of crust mantle lithosphere. We first use S velocities derive an initial then refine model by joint inversion topography gravity. final receiver functions strip away contributions...

Abstract Knowledge of the local state stress is critical in appraising intraplate seismic hazard. Inverting earthquake moment tensors, we demonstrate that principal directions New Madrid zone (NMSZ) differ significantly from those surrounding region. Faults NMSZ are incompatible with slip regional field favorably oriented relative to stress. We jointly analyze velocity, gravity, and topography develop a 3‐D crustal upper mantle density model, revealing uniquely dense lower crust beneath...

Abstract This paper develops a Monte Carlo algorithm for extracting three‐dimensional lithospheric density models from geophysical data. Empirical scaling relationships between velocity and create 3‐D starting model, which is then iteratively refined until it reproduces observed gravity topography. approach permits deviations uniform crustal velocity‐density scaling, provide insight into lithology prevent spurious mapping of anomalies the mantle. We test this on Proterozoic Midcontinent Rift...

Subduction at plate boundaries can have thermal, chemical, and physical impacts on broad regions of the continental interior, but these interactions are not as readily obvious deformation near margin. Such cryptic alteration has produced surface uplift in Colorado Plateau western Great Plains North America, which risen—largely undeformed—1.6 1.3 km, respectively, relative to eastern during Cenozoic. Accumulation Cretaceous–Cenozoic sediments accounts for only 300 m 400 Plains, leaving km 0.9...

Abstract Wastewater reinjection increases pore fluid pressure and can make faults frictionally unstable, triggering earthquakes. Little is known, however, about how regional geomechanical properties influence the likelihood that disposal will induce seismicity. We investigate impact of preinjection conditions on proportion possible fault orientations destabilized by a specified increase. Stress state most important factor, with 7 times as many planes unstable in extension than...

The modern topography of the Sierra Nevada (California, USA) has been attributed to rapid uplift following foundering negatively buoyant lithosphere into asthenosphere since ca. 10 Ma. Uplift now manifests as ∼2 km mean topographic relief between crest southern and western foothills 1–2 Sierran adjacent Basin Range. In this study, we use seismic P-wave velocity structures derived from teleseismic tomography estimate lithospheric density structure in region thus infer current sources support....

Abstract The stress tensor is an important property for upper crustal studies such as those that involve pore fluids and earthquake hazards. At tectonic plate scale, boundary forces mantle convection are the primary drivers of field. In many local settings (10–100 s km <10 depth) in interiors, we can simplify by assuming a constant background field perturbed heterogeneity density elasticity. Local orientation sometimes magnitude be estimated from borehole‐based observations when...

Seismic tomography has previously imaged the high-velocity “Isabella anomaly” southwest of Sierra Nevada beneath Tulare basin, a region ~1 km anomalous Pliocene subsidence. Additionally, it been proposed that eastern risen 1–2 since Miocene in response to removal dense lithospheric material. The Isabella anomaly variably interpreted as either this material or neutrally buoyant stalled fragment Farallon slab. To discriminate between these two, we estimate upper mantle density variations from...

Abstract The eastern Tennessee seismic zone (ETSZ) experiences the second highest rates of natural seismicity in central and United States (CEUS), following New Madrid area, yet cause elevated earthquake is unknown. We probe origin ETSZ using geomechanically constrained stress inversions focal mechanisms from 57 earthquakes, including 24 newly derived here five recent events not used previous studies. Highly oblique northwest–southeast (NW–SE) extension that unique CEUS dominates...

Research Article| November 07, 2018 Evidence for Strain Accrual in the Eastern Tennessee Seismic Zone from Earthquake Statistics Will Levandowski; Levandowski aDepartment of Geology, Colorado College, 14 East Cache La Poudre Street, Springs, 80903 U.S.A., will.levandowski@tetratech.comcNow at TetraTech, Inc., 1100 South McCaslin Boulevard, Suite #150, Superior, Colorado, U.S.A. Search other works by this author on: GSW Google Scholar Christine A. Powell bCenter and Information, The...

Abstract Seismic attenuation is generally greater in the western United States (WUS) than central and eastern (CEUS), but nature of this transition or location boundary poorly constrained. We conduct crustal seismic (Lg) tomography across a region that stretches from CEUS Rocky Mountains to Basin Range using total 115,870 amplitude measurements 106 earthquakes recorded on 544 stations five frequency bands spanning 0.5–16 Hz. Similar previous studies, we find higher WUS ( Q 0 ∼ 190) nominally...

The stress tensor is an important property for upper crustal studies such as those that involve pore fluids and earthquake hazards. At tectonic plate scale, boundary forces mantle convection are the primary drivers of field. In many local settings (10s to 100s km <10 depth) in interiors, we can simplify by assuming a constant background field perturbed heterogeneity density elasticity. Local orientation sometimes magnitude be estimated from borehole-based observations when available....