Physical Sciences and Mathematics Commons^™

Segmentation Of The Blanco Transform Fault Zone From Earthquake Analysis: Complex Tectonics Of An Oceanic Transform Fault, Jochen Braunmiller, John Nábělek

School of Geosciences Faculty and Staff Publications

The Blanco Transform Fault Zone (BTFZ) forms the ∼350 km long Pacific–Juan de Fuca plate boundary between the Gorda and Juan de Fuca ridges. Nearby broadband seismic networks provide a unique framework for a detailed, long-term seismotectonic study of an entire oceanic transform fault (OTF) system. We use regional waveforms to determine 129 earthquake source parameters; combined with 28 Harvard moment tensors, they represent the largest waveform derived OTF source parameter data set. Joint epicenter determination removes the northeasterly routine location bias. Projecting seismicity onto the BTFZ, we determine along-fault seismic slip rate variations. Earthquake source parameters and morphology indicate …

Alaska's Pavlof Volcano Ends 11-Year Repose, Christopher F. Waythomas, Stephanie G. Prejean, Stephen R. Mcnutt

School of Geosciences Faculty and Staff Publications

After an 11-year period of repose, Pavlof volcano on the Alaska Peninsula (Figure 1) began an episode of Strombolian eruption lasting 31 days, from 14 August to 13 September 2007.

The eruption began abruptly on 14 August after a minor increase in seismicity the previous day. Nearly continuous lava fountaining, explosions, and lahars caused by minor disruption of the ice and snow cover on the volcano characterized the eruption. The eruption also produced diffuse ash plumes that reached 5–6 kilometers above sea level, but the plumes were too small and did not extend high enough to affect local or regional …

Moho Depth And Poisson's Ratio In The Western–Central Alps From Receiver Functions, D. Lombardi, Jochen Braunmiller, E. Kissling, D. Giardini

School of Geosciences Faculty and Staff Publications

Current knowledge about deep crustal structure of the Alpine orogen has mainly been derived from P-wave velocity models obtained from active and passive seismic experiments. A complementary S-wave model to provide lithological constraints necessary for unique structural interpretation has been missing to date. In this paper, we present important new information on S-wave velocity model in the Alps. We applied the receiver function method using 6 yr of high quality data from 61 permanent and temporary stations sampling the Western–Central Alps. We determined first-order crustal features Moho depth (H) and average Vp/Vs ratio …

A Large New Species Of Lobatus (Gastropoda: Stromnidae) From The Neogene Of The Dominican Republic, With Notes On The Genus, Bernard M. Landau, Gijs C. Kronenberg, Gregory S. Herbert

School of Geosciences Faculty and Staff Publications

No abstract provided.

Earth Scientists And Public Policy: Have We Failed New Orleans?, Timothy H. Dixon, Roy K. Dokka

School of Geosciences Faculty and Staff Publications

Earth scientists rarely influence public policy or urban planning. In defiance of geologic reality, cities are established on or expanded into floodplains, wetlands, earthquake faults, and active volcanoes. One exception to our lack of influence is that shortly after a major natural disaster, there is a brief window of heightened public awareness that may lead to sensible regulation or relocation of infrastructure. After the 1933 Long Beach earthquake, for example, California building codes were improved to reduce earthquake hazard. After Mississippi River flooding in 1993, several U.S. cities designated parts of their low-lying flood-plain as green space.

Rethinking Early Earth Phosphorus Geochemistry, Matthew A. Pasek

School of Geosciences Faculty and Staff Publications

Phosphorus is a key biologic element, and a prebiotic pathway leading to its incorporation into biomolecules has been difficult to ascertain. Most potentially prebiotic phosphorylation reactions have relied on orthophosphate as the source of phosphorus. It is suggested here that the geochemistry of phosphorus on the early Earth was instead controlled by reduced oxidation state phosphorus compounds such as phosphite (HPO₃ ²⁻), which are more soluble and reactive than orthophosphates. This reduced oxidation state phosphorus originated from extraterrestrial material that fell during the heavy bombardment period or was produced during impacts, and persisted in the mildly reducing atmosphere. …