Publications

Information about reported encounters of aircraft with volcanic ash clouds from 1953 through 2009 has been compiled to document the nature and scope of risks to aviation from volcanic activity. The information, gleaned from a variety of published and other sources, is presented in database and spreadsheet formats; the compilation will be updated as additional encounters occur and as new...

[1] The postseismic stress accumulation τ(t) over the interval 0.004 to 880 days following the 2004 Parkfield earthquake (M6) can be inferred from GPS measurements of postseismic deformation. The stress relaxation τ(t) − τ′lt, where τ′l is the interseismic loading rate and t is the time after the earthquake, plotted as a function of the number of M > 1.5 aftershocks Na(t) that have...

Every three years the IAU Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report takes into account the IAU Working Group for Planetary System Nomenclature (WGPSN) and the IAU Committee on Small Body Nomenclature (CSBN)...

The origin of tholeiitic (TH) versus calc-alkaline (CA) magmatic trends has long been debated. Part of the problem stems from the lack of a quantitative measure for the way in which a magma evolves. Recognizing that the salient feature in many TH–CA discrimination diagrams is enrichment in Fe during magma evolution, we have developed a quantitative index of Fe enrichment, the Tholeiitic...

The Lunar Reconnaissance Orbiter Camera (LROC) is systematically imaging impact melt deposits in and around lunar craters at meter and sub-meter scales. These images reveal that lunar impact melts, although morphologically similar to terrestrial lava flows of similar size, exhibit distinctive features (e.g., erosional channels). Although generated in a single rapid event, the post-impact...

The spatiotemporal patterns of seismicity beneath Kilauea's south flank give insight to the structure and geometry of the decollement on which large, tsunamigenic earthquakes have occurred, and its relation to slow slip events (SSEs), which have been observed every 1 to 2 years since 1997. In order to record earthquakes triggered by a SSE that was predicted to occur in March 2007, a...

Ground deformation was monitored at earth fissures in areas of land subsidence induced by groundwater extraction in the southwestern United States. The ground deformation is consistent with the mechanism that fissures are caused by horizontal strains generated by bending of overburden in response to localized differential compaction. Subsidence profiles indicated that localized...

This publication is an update of an earlier report, U.S. Geological Survey (USGS) Geologic Investigation I-2812 by Wheeler and others (2003), titled ?Earthquakes in the Central United States-1699-2002.? Like the original poster, the center of the updated poster is a map showing the pattern of earthquake locations in the most seismically active part of the central United States. Arrayed...

We use newspaper accounts from the United States and Canada to assign modified Mercalli intensity (MMI) at 90 towns for the May 16, 1909 Northern Plains earthquake. Our MMI assignments generally are consistent with those plotted on Nuttli's (1976) isoseiemal map. The earthquake was felt over more than 1,500,000 km2 in the states of Minnesota, Montana, North Dakota, South Dakota, and...

We report the identification of compounds on Titan's surface by spatially resolved imaging spectroscopy methods through Titan's atmosphere, and set upper limits to other organic compounds. We present evidence for surface deposits of solid benzene (C6H6), solid and/or liquid ethane (C2H6), or methane (CH4), and clouds of hydrogen cyanide (HCN) aerosols using diagnostic spectral features...

I test a “clock-advance” model that implies triggered tremor is ambient tremor that occurs at a sped-up rate as a result of loading from passing seismic waves. This proposed model predicts that triggering probability is proportional to the product of the ambient tremor rate and a function describing the efficacy of the triggering wave to initiate a tremor event. Using data mostly from...

We provide an overview of features indicative of the interaction between water and lava and/or magma on Mars as seen by the High Resolution Imaging Science Experiment (HiRISE) camera during the Primary Science Phase of the Mars Reconnaissance Orbiter (MRO) mission. The ability to confidently resolve meter-scale features from orbit has been extremely useful in the study of the most...