Quaternary shortening at the Andean orogenic front (31°-33°S), Argentina: Current issues and challenges

Quaternary shortening at the Andean orogenic front (31°-33°s), Argentina: Current issues and challenges

 Carlos Costa1, Emilio Ahumada1, Benjamin Brooks2, Andrew Meigs3, Lewis Owen4, Thomas Rockwell5, Lindsay Schoenbohm6, Carlos Gardini1, Héctor Cisneros1, Fabricio Vázquez1, 7

  1. Universidad Nacional de San Luis, Argentina. costa@unsl.edu.ar
  2. U.S. Geological Survey, USA
  3. Oregon State University, USA
  4. University of Cincinnati, USA
  5. San Diego State University, USA
  6. University of Toronto, Canada
  7. CONICET

Outstanding exposures, new data, and novel hypotheses developed during the last decade have turned the frontal deformation zone of the Andes between 31°S and 33°S (Fig. 1) into one of the most promising areas worldwide for improving the understanding on mountain building processes and seismic hazards related to thrust tectonics.

Because the Andes are relatively narrow in these latitudes, the geodetic signal in the backarc is dominated by the subduction zone locking process at the Chile trench. Nonetheless the geodetic analysis provides some useful constraints on the location and rates of modern backarc shortening, though not necessarily on the vergence. It is currently understood that backarc shortening occurs at rates of ~4-5mm/yr over a zone that is ~30km wide (across-strike) (Brooks et al., 2003; Kendrick et al., 2006). In the north (31°- 32°10° S) this would imply that the west-vergent, Eastern Precordilleran structures are the most likely to be active, while south of 32°10° S the east-vergent structures in the Southern Precordillera belt are likely to be most active (Fig. 1).

Continue reading “Quaternary shortening at the Andean orogenic front (31°-33°S), Argentina: Current issues and challenges”

New papers: paleotsunamis in Oman, Tohoku-oki tsunami 2011 in Japan

Two new tsunami papers have been published recently, and I am happy to be co-author of one of them. In Hoffmann et al. 2012 we report on our observations along the NE Omani coast between Fins and Sur. We found a ridge of imbricated boulders parallel to the coast, but in heights of several meters above m.s.l. on top of a cliff and dozens of meters inland. Also, extremely large blocks clearly stemming from the cliff were found. We used LiDAR to determine the mass of very large blocks (up to 40 t) and found this method to result in far lower weights than estimated with the classical method. Continue reading “New papers: paleotsunamis in Oman, Tohoku-oki tsunami 2011 in Japan”

Report on the coseismic and secondary effects of the May 22, 2012 Pernik EQ, Mw5.6, W Bulgaria

Our colleagues from the Bulgarian Academy of Science, Geological Institute “Strashimir Dimitrov“, have published a report on the coseismic and secondary effects of the May 22, 2012 Pernik earthquake, Western Bulgaria. The earthquake had a magnitude of MW5.6, see this special website of EMSC. Radulov et al. report intensities of up to VII (MSK) and various coseismic and secondary earthquake effects. Continue reading “Report on the coseismic and secondary effects of the May 22, 2012 Pernik EQ, Mw5.6, W Bulgaria”

Active Fault Database for Northern Greece

Databases for active faults are a major input for seismic hazard assessment and have been widely developed in several countries (such as USA, Japan, Italy and New Zealand). Despite the fact that Greece is the country of highest seismicity in Europe where almost 50% of the total seismic energy is realized, no official or unofficial active fault database exists. This is partly due to the fact that there are so many active faults that introduce a heavy workload, whereas several of them are also located offshore. This is particularly difficult for engineers since according to the latest the seismic building code that was released in 2000, no houses should be founded on active faults. Continue reading “Active Fault Database for Northern Greece”

Session on “Seismic hazard modeling”: 86th National Congress of the Società Geologica Italiana, 18-20 September 2012

The Italian Geological Society (Societą Geologica Italiana), founded in 1881, organizes its 86th meeting in Calabria, Southern Italy (18-20 September 2012). The meeting is entitled

THE MEDITERRANEAN: A GEOLOGICAL ARCHIVE FROM PAST TO THE PRESENT

http://www.sgi2012.unical.it/info_eng.html

Within this meeting, we will held a session on Seismic Hazard Modelling.

We invite those of you interested to consider participating to the meeting and presenting an abstract (in ours or any other session).

Continue reading “Session on “Seismic hazard modeling”: 86th National Congress of the Società Geologica Italiana, 18-20 September 2012”

Wanderlust (1) – Magaro Peak

Sitting in an office after sunset and browsing any kind of Earth Explorer makes a lot of people think about lovely places far away. We geoscientists are in a quite comfortable stuation with field trips and meetings all over the world. But maybe sometimes there are thoughts about places you haven’t been to. I would like to introduce this section as a suggestion for your next holiday or even field trip with bits and pieces of culture, scenery and geology. Continue reading “Wanderlust (1) – Magaro Peak”