EPSS Colloquium - winter-2015

Jan. 8, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Belle Philibosian - Institut de Physique du Globe

Seminar Description coming soon.

Jan. 15, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Shanan Peters -

Seminar Description coming soon.

Jan. 22, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Seul Gi Moon -

Seminar Description coming soon.

Jan. 27, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Seul Gi Moon - MIT

Seminar Description coming soon.

Jan. 29, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Adam Forte - ASU

Seminar Description coming soon.

Feb. 5, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Kate Scharer - USGS

Large earthquakes are infrequent along a single fault, and therefore historic, well-characterized earthquakes exert a strong influence on fault behavior models. This is true of the 1857 Fort Tejon earthquake (estimated M7.7–7.9) on the southern San Andreas Fault (SSAF), but an outstanding question is whether the 330 km long rupture was typical. New paleoseismic data for six to seven ground-rupturing earthquakes from the Frazier Mountain site on the Big Bend and recent work from the Elizabeth Lake trench site on the Mojave sectrion of the SSAF restrict the pattern of possible ruptures on the 1857 stretch of the fault. Specifically, in conjunction with existing sites, we show that over the last ~650 years, at least 75%of the surface ruptures are shorter than the 1857 earthquake, with estimated rupture lengths of 100 to <300 km. These results suggest that the 1857 rupture was unusual, perhaps leading to the long open interval, and that a return to pre-1857 behavior would increase the rate of M7.3–M7.7 earthquakes.

Feb. 12, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• David Sandwell - UCSD - Scripps Institution of Oceanography

Marine gravity from satellite altimetry has become a primary tool for investigating the tectonics of the remote ocean basins as well as unexplored continental margins. Recently two new non-repeat altimeter data sets have become available, resulting in a factor of 2-4 improvement in maps of the global marine gravity field. We use these data along with shipboard bathymetry data and earthquake focal mechanisms to constrain the magnitude of the regional stress field along the global mid-ocean ridge [Luttrell and Sandwell, JGR, 2012]. Slower spreading ridges require at least 25-40 MPa of ridge perpendicular extension while less extensional stress (10-30 MPa) is required at the faster spreading ridges. Our modeling suggests that a deep transform valley is an essential feature of the ridge-transform spreading center.

Feb. 26, 2015
4 p.m. - 5 p.m.
1-434 PAB

Presented By:

• Eric Korpela - UC Berkeley

Joint EPSS-Physics colloquium Volunteer computing, also known as public-resource computing, is a form of distributed computing that relies on members of the public donating the processing power, Internet connection, and storage capabilities of their home or business computers. Projects that utilize this mode of distributed computation can potentially access millions of Internet-attached central processing units (CPUs) that provide PFLOPS (thousands of trillions of floating-point operations per second) of processing power. In addition, these projects can access the talents of the volunteers themselves. Projects span a wide variety of domains including astronomy, biochemistry, climatology, physics, and mathematics. I'll provide an introduction to volunteer computing and some of the difficulties involved in its implementation. I'll describe, BOINC, the dominant infrastructure for volunteer computing and provide descriptions of a few projects that may be of interest to geophysicists, physicists and astronomer. And I'll also describe some of the resources available for scientists interested in starting their own volunteer computing projects.

March 5, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• William Newman - UCLA

Seminar Description coming soon.

March 12, 2015
4 p.m. - 5 p.m.
Geology 3656

Presented By:

• Carolyn Porco - Space Science Institute

In 2005, the Cassini mission at Saturn discovered a remarkable and unique geological province at high southern latitudes on the small icy moon, Enceladus. Towering jets of powder-sized, salty ice particles, along with water vapor laced with organic compounds and accompanied by a shocking ~5GW of thermal radiation, vent from four prominent fractures crossing the moon's 500-km-wide south polar terrain (SPT). These observations, together with gravity data collected by Cassini in the last several years, point a liquid layer beneath the province that supplies the eruptions, but whether or not it is regional or global is not completely certain. I will present the first comprehensive comparison of the spatial distribution and temporal variability of the geysering, the tidal stresses exerted on the moon by Saturn, and the anomalous thermal emission, and discuss the implications of these findings for the moon’s interior structure. I will also briefly describe the means by which Enceladus supplies material to Saturn's E ring.