Publications

Cassini observations show that Saturn’s moon Titan is slightly oblate. A fourth-order spherical harmonic expansion yields north polar, south polar, and mean equatorial radii of 2574.32 ± 0.05 kilometers (km), 2574.36 ± 0.03 km, and 2574.91 ± 0.11 km, respectively; its mean radius is 2574.73 ± 0.09 km. Titan’s shape approximates a hydrostatic, synchronously rotating triaxial ellipsoid but...

A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon...

Rotational motions generated by large earthquakes in the far field have been successfully measured, and observations agree well with the classical elasticity theory. However, recent rotational measurements in the near field of earthquakes in Japan and in Taiwan indicate that rotational ground motions are 10 to 100 times larger than expected from the classical elasticity theory. The near...

Evaluation of the extent of volatile element recycling in convergent margin volcanism requires delineating likely source(s) of magmatic volatiles through stable isotopic characterization of sulfur, hydrogen and oxygen in erupted tephra with appropriate assessment of modification by degassing. The climactic eruption of Mt. Mazama ejected approximately 50 km3 of rhyodacitic magma into the...

More than 65 potentially active volcanoes on the Kamchatka Peninsula and the Kurile Islands pose a substantial threat to aircraft on the Northern Pacific (NOPAC), Russian Trans-East (RTE), and Pacific Organized Track System (PACOTS) air routes. The Kamchatka Volcanic Eruption Response Team (KVERT) monitors and reports on volcanic hazards to aviation for Kamchatka and the north Kuriles...

Many investigators have applied the liquefaction potential index (LPI) to map regional liquefaction hazard. LPI, which integrates the liquefaction potential of susceptible soil elements at a specific location into a single value, has been used to assess both (1) spatial variability of liquefaction potential, and (2) liquefaction potential of surficial geologic units. A promising...

The October 11, 1918 ML 7.5 earthquake in the Mona Passage between Hispaniola and Puerto Rico generated a local tsunami that claimed approximately 100 lives along the western coast of Puerto Rico. The area affected by this tsunami is now significantly more populated. Newly acquired high-resolution bathymetry and seismic reflection lines in the Mona Passage show a fresh submarine...

Moloka‘i, with the most extensive coral reef in the main Hawaiian Islands, is especially sacred to Hina, the Goddess of the Moon. As Hinaalo, she is the Mother of the Hawaiian people; as Hinapuku‘a, she is the Goddess of Fishermen; and in the form Hina‘opuhalako‘a, she is the Goddess who gave birth to coral, coral reefs, and all spiny marine organisms. Interdependence between the reef’s...

This report summarizes the discussions and information presented during the workshop on Aseismic Slip, Tremor, and Earthquakes. Workshop goals included improving coordination among those involved in conducting research related to these phenomena, assessing the implications for earthquake hazard assessment, and identifying ways to capitalize on the education and outreach opportunities...

Meter-size granite basins are found in a 180-km belt extending south from the South Fork of the Kings River to Lake Isabella on the west slope of the southern Sierra Nevada, California. Their origin has long been debated. A total of 1,033 basins have been inventoried at 221 sites. The basins occur on bedrock granitic outcrops at a median elevation of 1,950 m. Median basin diameter among...

This paper studies a parsimonious model of landslide motion, which consists of the one-dimensional diffusion equation (for pore pressure) coupled through a boundary condition to a first-order ODE (Newton's second law). Velocity weakening of sliding friction gives rise to nonlinearity in the model. Analysis shows that solutions of the model equations exhibit a subcritical Hopf bifurcation...

We analyzed the evolution of volcano‐tectonic (VT) seismicity and deformation at three basaltic volcanoes (Kilauea, Mauna Loa, Piton de la Fournaise) during phases of magma accumulation. We observed that the VT earthquake activity displays an accelerating evolution at the three studied volcanoes during the time of magma accumulation. At the same times, deformation rates recorded at the...