Publications

Earthquake engineering is increasingly using nonlinear response history analysis (RHA) to demonstrate the performance of structures. This rigorous method of analysis requires selection and scaling of ground motions appropriate to design hazard levels. This paper presents a modal-pushover-based scaling (MPS) procedure to scale ground motions for use in a nonlinear RHA of buildings. In the MPS metho

High-resolution aeromagnetic surveys of the Cascade Range and Yakima fold and thrust belt (YFTB), Washington, provide insights on tectonic connections between forearc and back-arc regions of the Cascadia convergent margin. Magnetic surveys were measured at a nominal altitude of 250 m above terrain and along flight lines spaced 400 m apart. Upper crustal rocks in this region have diverse magnetic p

We apply a recently developed and validated numerical model of tsunami propagation and runup to study the inundation of Resurrection Bay and the town of Seward by the 1964 Alaska tsunami. Seward was hit by both tectonic and landslide-generated tsunami waves during the MWMW 9.2 1964 megathrust earthquake. The earthquake triggered a series of submarine mass failures around the fjord, which resulted

The formation process of recent gullies on Mars is currently under debate. This study aims to discriminate between the proposed formation processes - pure water flow, debris flow and dry mass wasting - through the application of geomorphological indices commonly used in terrestrial geomorphology. High-resolution digital elevation models (DEMs) of Earth and Mars were used to evaluate the drainage c

Industry seismic reflection data, oil test well data, interpretation of gravity and magnetic data, and seismic refraction deep-crustal profiles provide new perspectives on the subsurface geology of San Fernando Valley, home of two of the most recent damaging earthquakes in southern California. Seismic reflection data provide depths to Miocene–Quaternary horizons; beneath the base of the Late Mioce

Net changes in thickness and volume of glacial ice and perennial snow at Mount Rainier, Washington State, have been mapped over the entire edifice by differencing between a highresolution LiDAR (light detection and ranging) topographic survey of September-October 2007/2008 and the 10 m lateral resolution U.S. Geological Survey digital elevation model derived from September 1970 aerial photography.

We produced the first complete, 1:15 M-scale global geologic map of Jupiter’s moon Io, based on a set of monochrome and color Galileo–Voyager image mosaics produced at a spatial resolution of 1 km/pixel. The surface of Io was mapped into 19 units based on albedo, color and surface morphology, and is subdivided as follows: plains (65.8% of surface), lava flow fields (28.5%), mountains (3.2%), and p

The key to advancing the predictability of rainfall-triggered landslides is to use physically based slope-stability models that simulate the transient dynamical response of the subsurface moisture to spatiotemporal variability of rainfall in complex terrains. TRIGRS (transient rainfall infiltration and grid-based regional slope-stability analysis) is a USGS landslide prediction model, coded in For

Aseismic deformation transients such as fluid flow, magma migration, and slow slip can trigger changes in seismicity rate. We present a method that can detect these seismicity rate variations and utilize these anomalies to constrain the underlying variations in stressing rate. Because ordinary aftershock sequences often obscure changes in the background seismicity caused by aseismic processes, we

We present evidence of widespread aeolian activity in the Arabia Terra/Meridiani region (Mars), where different kinds of aeolian modifications have been detected and classified. Passing from the regional to the local scale, we describe one particular dune field in Meridiani Planum, where two ripple populations are distinguished by means of different migration rates. Moreover, a consistent change i

Imbrian-aged basalt ponds, located on the floor of South Pole-Aitken (SPA) basin, are used to provide constraints on the composition and evolution of the far side lunar mantle. We use forward modeling of the Lunar Prospector Gamma Ray Spectrometer thorium data, to suggest that at least five different and distinct portions of the far side lunar mantle contain little or no thorium as of the Imbrian

Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0–5.0) for dendritic networks; comparisons with Rb values determined for Titan basi