PLANETARY MUSINGS

Entries in "Tectonics"

Opportunities for Graduate Study in Planetary Geology and Geophysics

The Department of Geological Sciences at Case Western Reserve University is currently accepting applications from students interested in pursuing graduate studies leading to M.S. and Ph.D. degrees in the earth, environmental, and planetary sciences. The Department offers flexible, research-intensive programs for graduate students. Applications are accepted on a continuing basis, though students requesting financial support are strongly encouraged to apply by February 1, 2007. Online applications are available through the School of Graduate Studies.

There are several opportunities for students interested in pursuing research in planetary science, particularly in the areas of planetary geology and geophysics, high-pressure and temperature geochemistry, and meteorites working with a group of faculty that includes myself, Prof. Harvey, and Prof. Van Orman.

At present I am collaborating with students to (1) understand the nature of Mars' crust and lithosphere and tectonic activity and (2) the mechanisms responsible for driving Ganymede's magnetic field. Additional opportunities within these may be available depending upon interest. We are also in the process of focusing new study on large lunar impact basins and the coupled internal and tectonic evolution of Mercury.

I would welcome the opportunity to discuss opportunities for graduate study in planetary science and/or geophysics with interested students (my contact info is available on my webpage).

Sumatra-Andaman Islands Earthquake

Bilham, R, A Flying Start, Then a Slow Slip, Science, 308, 1126-1127, (2005), http://dx.doi.org/10.1126/science.1113363

Lay, T, H Kanamori, CJ Ammon, M Nettles, SN Ward, RC Aster, SL Beck, SL Bilek, MR Brudzinski, R Butler, HR DeShon, G Ekstrom, K Satake, S Sipkin, The Great Sumatra-Andaman Earthquake of 26 December 2004, Science, 308, 1127-1134, (2005), http://dx.doi.org/10.1126/science.1112250

Science published a series of four papers on the Sumatra earthquake in their May 20, 2005 issue. We are reading the articles above in Journal Club this week.... The devastating Dec. 26, 2004 Sumatra earthquake has opened a new box of scientific questions about the earth because of how the earthquake proceeded. These articles indicate that there was no place on Earth that did not move at least a centimeter as a result of the earthquake. Other previous papers indicated that the Earth's rotation even changed, but imperceptively I think. Anyway, there are two main points in these articles that I think are worth noting. First, with the normal plate convergence in this region at ~14 mm/yr, the ~10 meters of slip that occured in seconds is phenomenal at a minimum, and these authors rightfully point out that would normally take ~700 years. So, how much of the total plate movement is due to large slips like this earthquake compared to the smaller, daily-to-yearly earthquakes? Following on from that is the second point: The variation in sliprate along the rupture from south to north. I would guess that variations in stress (and release of it) are the most important controls on this process, but are there others? For example, the total slip in the north according to Lay et al is of similar magnitude as the south (maybe a little smaller), but must have been slow (aseismic) because it was picked up by tiltmeters and GPS, not broadband seismometers. What controls this process? Might it be related to the 30 Myr variation in age of the crust along the rupture too?