In September, Klaus and me lead a MSc student excursion to southwestern Germany. We not only went through the entire stratigraphy of that area (mainly Triassic and Jura), but also visited the salt mine in Stetten, quarries in Dotternhausen (opalinus clay, posidonia schist, Malm), the Kaiserstuhl carbonatite volcano complex and the Upper Rhine Graben area. One of my personal highlights was the Freudenstädter Graben, a small tectonic graben striking NW-SE, whose NE main fault is exposed in an old mine in Hallwangen. more
Nature published three articles on the Sumatra April 2012 mega-strike-slip earthquakes. I am pretty sure that at least one of them will be discussed intensely. Earlier this year, two earthquakes with magnitudes of M8.6 and M8.2, respectively, occurred in the Indian Ocean off Sumatra. The epicentres were close to the epicentral area of the 2004 Christmas event, but further to the SW and entirely on the Indo-Australian plate. This was surprising for many reasons: We did not expect such strong strike-slip quakes, we did not expect them to happen intraplate, and we were surprised by the complex en echelon and orthogonal fault pattern. more
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. more
Today’s Friday links are mostly about cake geology and scientists playing with food, but let’s start with something different. Yesterday, volcano Fuego (“fire”) erupted in Guatemala and produced an impressive column of ash and smoke. This beautiful stratovolcano is only 40 km from Guatemala City and one of the most active volcanos of Central America. more
The Sparta Fault in Greece is marked by one of the most impressive mountain fronts I’ve ever seen. A huge (yes, huge!) fault scarp has developed, traceable for kilometers; the fault itself is more than 60 km long. Ancient Sparta has been devastated by the last known major (M>7) earthquake that happened at this fault in 464 BC. Now, Papanikolaou et al. have published new data on this fault. They examined how paramaters like throw, segmentation, and catchments vary along strike and created a new seismic hazard map, showing a site-specific long-term recurrence interval of ~1.8 ka (+/- 450 a). more
A new paper has been published online first by Hinzen et al. on their archeoseismological study in Cologne, Germany. During recent archeological excavations, a number of damaged structures from Roman to Medieval times have been discovered and described among them a synagoge, the Praetorium, and a Roman well. Since damaging historical earthquakes are documented for the Lower Rhine Embayment, seismic shaking was a good guess to have caused the observed damage. more
Two really strong earthquakes happened yesterday at the Mid-Atlantic Ridge in the Jan Mayen Islands area. The first one had a magnitude of M6.6, the second one, around ten minutes later, had M5.3. Moment tensor solutions show clear strike slip along a transform fault west of the ridge. The seismicity map shows that events like yesterday’s don’t come as a suprise: more
One of the coolest things I recently read about was the Syracuse University Lava Project. I mean, how cool is it to produce your own lava at 1200°C and to let it flow on Campus? Pretty cool. And, as you can see on these images, it is a great way to teach children how cool geoscience is. Watch the beautiful structures developing when the lava cools down: more
A new earthquake catalogue has been published by the GFZ Potsdam (German Research Centre for Geosciences). The Database covers the European-Mediterranean area and reaches back to AD1000. This is good news and an important step on our long way to collect all earthquake information available in one place. I say it’s a first step only, because we know much more than the catalogue incorporates: Besides ~100 years of instrumental records we have historical data covering hundreds of years in many regions, but reaching back to some thousands of years in regions like Greece and Israel. Then, there’s archaeoseismological data of course and paleoseismology, which can resolve events that happened thousands of years ago. more
This morning at 03:00 UTC an earthquake with magnitude MW7.7 occurred in the Sea of Okhotsk. Due to its great depth of more than 600 km no tsunami was triggered and surface shaking was pretty low, however, the event was felt in a wide area. Moment tensor solutions indicate a thrust event. Historical seismicity tells us that significant earthquakes are likely to happen in the region and mostly occur in great depths, but at this certain location only few events have been registered during the last decades. more
