Mousumi Roy

• PhD, 1997, Massachusetts Institute of Technology
• Professor (Associate) at University of New Mexico

The goal of this study is to explore “ideal” analytic functional forms that best fit the topographic shape of N = 190 isolated stratovolcanoes from around the world. Using a stochastic model for the piling of lava flows to demonstrate one set of physical processes that give rise to a stratovolcano's topography, we find that although the ideal form...

This study explores how the continental lithospheric mantle (CLM) may be heated during channelized melt transport when there is thermal disequilibrium between (melt-rich) channels and surrounding (melt-poor) regions. Specifically, I explore the role of disequilibrium heat exchange in weakening and destabilizing the lithosphere from beneath as melts...

The ability to accurately and reliably obtain images of shallow subsurface anomalies within the Earth is important for hazard monitoring and a fundamental understanding of many geologic structures, such as volcanic edifices. In recent years, machine learning (ML) has gained increasing attention as a novel approach for addressing complex problems in...

The forces that drove rock uplift of the low-relief, high-elevation, tectonically stable Colorado Plateau are the subject of long-standing debate. While the adjacent Basin and Range province and Rio Grande rift province underwent Cenozoic shortening followed by extension, the plateau experienced approximately 2 km of rock uplift without significant...

We use continuous measurements of GPS sites from across the Rio Grande Rift, Great Plains, and Colorado Plateau to estimate present-day surface velocities and strain rates. Velocity gradients from five east-west profiles suggest an average of ∼1.2 nanostrains/yr east-west extensional strain rate across these three physiographic provinces. The exten...

This study is motivated by the observed variability in trace element isotopic and chemical compositions of primitive (SiO2< ${\mathrm{O}}_{2}< $52 wt %) basalts in southwest North America (SWNA) during the Cenozoic transition from subduction to extension. Specifically, we focus on processes that may explain the enigmatic observation that in some lo...

Surface deformation plays a key role in illuminating magma transport at active volcanoes, however, unambiguous separation of deep and shallow transport remains elusive. The Socorro Magma Body (SMB) lacks an upper crustal magma transport system, allowing us to link geodetic measurements with predictions of numerical models investigating rheologic he...

Surface deformation measurements play a key role in illuminating magma transport systems at active volcanic systems, however, unambiguous separation of deep and shallow transport remains elusive. The Socorro Magma Body (SMB) lacks an upper crustal magma transport system, allowing us to link geodetic measurements with predictions of numerical models...

This study explores how the continental lithospheric mantle (CLM) may be heated during channelized melt transport when there is thermal disequilibrium between (melt-rich) channels and surrounding (melt-poor) regions. Specifically, I explore the role of disequilibrium heat exchange in weakening and destabilizing the lithosphere from beneath as melts...

This study explores melt-infiltration and melt-rock interaction as a means of shaping the continental lithosphere from beneath. Specifically, we focus upon the role of thermal disequilibrium between melt and the surrounding solid as a means for heating and modifying the continental lithospheric mantle. We use simple pore-network models to estimate...

Estimating subsurface density is important for imaging various geologic structures such as volcanic edifices, reservoirs, and aquifers. Muon tomography has recently been used to complement traditional gravity measurements as a powerful method for probing shallow subsurface density structure beneath volcanoes. Gravity and muon data have markedly dif...

Imaging shallow subsurface density structure is an important goal in a variety of applications, from hydrogeology to seismic and volcanic hazard assessment. We assess the effectiveness of surface and subsurface gravity measurements in estimating the density structure of a well-characterized rock volume: the mesa (a small, flat-topped plateau) upon...

We present an underground cosmic ray muon tomographic experiment imaging 3D density of overburden, part of a joint study with differential gravity. Muon data were acquired at four locations within a tunnel beneath Los Alamos, New Mexico, and used in a 3D tomographic inversion to recover the spatial variation in the overlying rock-air interface, and...

We present an underground cosmic ray muon tomographic experiment imaging 3D density of overburden, part of a joint study with differential gravity. Muon data were acquired at four locations within a tunnel beneath Los Alamos, New Mexico, and used in a 3D tomographic inversion to recover the spatial variation in the overlying rock–air interface, and...

Within continental interiors far from plate boundaries, we hypothesize that the architecture of the lithosphere will influence dynamic pressure gradients produced as the lithosphere moves relative to the underlying asthenosphere. We investigate how these dynamic pressure gradients affect melt migration by percolative flow within the mantle beneath...

The stability of the lithospheric mantle beneath the ancient cratonic cores of continents is primarily a function of chemical modification during the process of melt extraction. Processes by which stable continental lithosphere may be destabilized are not well-understood, although destabilization by thickening and removal of negatively-buoyant lith...

The forces that drove rock uplift of the low-relief, high-elevation, and tectonically stable Colorado Plateau (CP) are the subject of a great deal of renewed interest. Xenoliths and seismic observations suggest that the lithosphere beneath the CP is thicker than in the surrounding regions. The onset of Cenozoic magmatism is observed to migrate inwa...

Surface deformation across the western US plate boundary depends on not only the mantle forces driving the deformation, but also on the strength of the crust and mantle lithosphere that transmit those forces. Previous analyses of seismic anisotropy in the region imply that Pacific-NA plate boundary deformation penetrates into the mantle in northern...

We use three years of measurements from 25 continuous GPS stations across the Rio Grande Rift in New Mexico and Colorado to estimate surface velocities, time series, baselines, and strain rates. The stations are part of the EarthScope Rio Grande Rift experiment, a collaboration between researchers at the University of Colorado at Boulder, the Unive...

Surface deformation across the western US plate boundary depends on not only the mantle forces driving the deformation, but also on the strength of the crust and mantle lithosphere that transmit those forces. Previous analyses of seismic anisotropy in the region imply that Pacific-NA plate boundary deformation penetrates into the mantle in northern...

Seismic anisotropy measurements from shear-wave splitting at the San Andreas fault (SAF) system show fault-parallel fast-polarization directions near the fault and east-west (E-W) orientations away from the fault in northern California. In southern California, a cryptic near-fault region of fault-parallel fast-polarization directions are observed w...

Channel orientation, gradient, drainage basin spacing, drainage patterns, and alluvial fan sedimentology define a set of geomorphic observables for fingerprinting modes of extensional tectonism in convergent settings. Anomalous, finely textured trellis drainage patterns in the Alps are spatially coincident with the low-angle Simplon and Brenner det...

Upper mantle seismic anisotropy patterns at the San Andreas fault system are uniquely suited to investigating the role of crust-mantle coupling within the lithosphere. Published interpretations of seismic anisotropy in northern California include a two-layer model with fault-parallel anisotropy in the upper layer and nearly fault- perpendicular, E-...

In the landscape of the western United States, the Colorado Plateau features as a large physiographic province whose rock and surface uplift remain enigmatic. While the debate over the timing and distribution of uplift of the Colorado Plateau is ongoing, the goal of this study is to quantify and sum the expected contributions from known processes:...

The Colorado Plateau is a low-relief, high elevation physiographic province (average elevation ~ 1.9 km) within interior North America with an enigmatic relationship to the Mesozoic-Cenozoic orogenic processes at the western plate margin. The timing and mechanism of Cenozoic rock and surface uplift of the plateau are the subject of ongoing debate....

The rock and surface uplift of the Colorado Plateau and its relative tectonic stability remain enigmatic features of the Cenozoic evolution of North America. In this work we bring together observations from a range of datasets: patterns of Tertiary magmatism, rock exhumation, and erosion, the composition and physical properties of mantle xenoliths...

The Rio Grande rift is the easternmost actively deforming province of the western margin of North America. Geologic observations suggest the character of rifting changes from north to south, with a narrow rift marked by linear topographic depressions in Colorado and northern New Mexico grading to a broad ``basin and range'' expression in south-cent...

The lithospheric architecture of the Colorado Plateau-Rio Grande rift transition zone reflects a narrow corridor of active tectonism and magmatism between the tectonically stable Colorado Plateau and the stable interior of North America. In this paper we analyze Bouguer gravity data, crustal thickness variations, xenolith data, and seismic wave spe...

The Rio Grande rift is a Cenozoic continental rift zone that trends south from central Colorado through New Mexico and merges with a broader extensional zone in west Texas and Chihuahua, Mexico. The net upper crustal extension increases southward along the rift, accompanied by a southward-widening of the rift from a narrow zone encompassing a singl...

The CD-ROM experiment has produced a new 4-D understanding of the structure and evolution of the lithosphere of the southern Rocky Mountain region. We identify relicts of at least four subduction zones that were formed during assembly of dominantly oceanic terranes in the Paleoproterozoic. Crustal provinces with different geologic histories corresp...

The Colorado Mineral Belt (CMB) is delineated as a belt of mostly Laramide mineralization within a broader zone of Laramide and older magmatism in central Colorado. This paper focuses on the profound negative Bouguer gravity anomaly that coincides with this broader zone of protracted magmatic activity, and is among the largest gravity anomalies in...

In the southern Rocky Mountains and Rio Grande rift, rock cooling patterns from apatite fission-track (AFT) data spatially correlate with areas of voluminous middle Tertiary caldera-complex magmatism. We use thermochronology and gravity data to explore lithospheric modification by voluminous middle Tertiary magmatism. These data are not traditional...

Deformation within continents involves multi-scale responses such as localized brittle faulting (mainly in the upper crust) and more distributed deformation commonly modeled as elastic, viscous, or visco-elastic behavior (within the lower crust and upper mantle). This study investigates the interaction between localized faulting and distributed ela...

The Colorado Mineral Belt (CMB) is delineated as a belt of mostly Laramide mineralization within a broader zone of Laramide and older magmatism in central Colorado. One of North America's largest Bouguer gravity anomalies coincides with this broad NE-trending zone of protracted magmatic activity. Seismic studies suggest that parts of the CMB region...

The Stara Planina is an E–W-trending range within the Balkan belt in central Bulgaria. This topographically high mountain range was the site of Mesozoic through early Cenozoic thrusting and convergence, and its high topography is generally thought to have resulted from crustal shortening associated with those events. However, uplift of this belt ap...

Apatite fission track (AFT) and (U-Th)/He data from the Sandia Mountains and Hagan embayment provide new insights into the thermal and tectonic evolution of the eastern flank of the Rio Grande rift in northern New Mexico. AFT and (U-Th)/He data reveal rapid cooling in the Sandia Mountains between 22 and 17 Ma, followed by a decrease in cooling rate...

This paper investigates how rheologic stratification within the crust affects the formation and long-term evolution of fault systems at a strike-slip plate boundary. We present an analytic model of deformation at a strike-slip plate margin within a two-layer viscoelastic crust, with fixed shear modulus but varying viscosity in each layer. Faulting...

We present a numerical model of deformation at a strike-slip plate boundary within a linear viscoelastic crust, which is driven by far-field plate motions and basal mantle velocities. The crust is assumed to have uniform elastic properties but continuously varying viscosity as a function of depth. Brittle faulting is represented by static elastic d...

A viscoelastic model of crustal deformation suggests that the formation and evolution of strike-slip fault systems are strongly influenced by rheologic contrasts between the upper and lower crust. When deformation is driven by a narrow zone of high shear in the mantle, the presence of a low-viscosity lower crustal layer underlying a primarily elast...

Laboratory studies suggest that earthquake nucleation involves a transition from quasi-static slip when inertial effects are negligible to inertia-driven, dynamic motion. This transition occurs via quasi-dynamic motion, during which the effects of inertia become increasingly important. The characteristics of this transition, which depend on frictio...