Posts in the category »  Earthquake «  ( 113 Posts )

  • Earthquake Geology of the 16 April, 2016, Kumamoto Earthquake – report by Koji Okumura

    On 16 April an earthquake of magnitude Mw7.0 hit the district of Kumamoto, Kyushu Island, Japan. The quake was preceeded by a Mw6.1 foreshock one day before. It occurred on the ENE striking, right lateral Futagawa-Hinagu fault zone. Our colleague Koji Okumura from Hiroshima University has prepared a short report on this surface-rupturing event. Download the report here (PDF, 612 kb). The report will be continuously revised and corrected, so check for regular updates. Thanks Koji for providing this summary!

  • A Holocene surface rupture in Germany

    I am quite happy that our new paper has finally been published in GJI. We worked on a fault between Aachen and Cologne in Germany and found that there has been a surface rupturing earthquake less than 9000 years ago, and possibly not much older than 2500 years BP. The area is of interest also because in 1755/56 a series of damaging earthquakes hit Düren and its surroundings – these are the strongest historical events in Germany that we know of. The quakes were felt as far away as Berlin, Strasbourg, and London, yet there were no primary ruptures. “Our” quake must have been much stronger… more

  • IRSN report on the Napa Earthquake, California (M6, 2014-08-24)

    Our colleagues Stéphane Baize and Oona Scotti from the French IRSN finished a report on the 2014 Napa Earthquake: Post-seismic survey report, with special focus on surface faulting. On 24 August 2014, an earthquake of magnitude Mw6 occurred on the West Napa Fault in shallow depth. The quake caused significant damage, an interesting pattern of surface ruptures, and the immediate attention of hundreds of geologists. The primary and secondary effects were mapped only hours after the event, which turned out to be extremely important – a large amount of afterslip was recorded in the following days. The earthquake was not only recorded by a huge seismometer network, but the ground motion was also captured by GPS sensors and InSAR images. The new IRSN report is especially concerned with the surface faulting hazard, since this agency is responsible for the safety of nuclear installations in France.  more

  • New data on the 17 Nov, 2015, M6.4 South Lefkada earthquake

    Our colleague Efthymios Lekkas kindly uploaded a new report on the recent South Lefkada Earthquake. If you can read Greek, have a look at this website: http://www.edcm.edu.gr/. Alternatively, you can download the slideshow from his personal website here as a PDF: http://www.elekkas.gr/images/stories/Frontpage/2015_Lefkada/lefkada2015.pdf

    The PDF contains info on the tectonic setting, historical and instrumental seismicity, followed by a collection of the earthquake (environmental) effects. more

  • A preliminary report on the 17 Nov, 2015, M6.4 South Lefkada earthquake, Ionian Sea, Greece

    On 17 November, 2015, a MW6.4 strike-slip earthquake occurred in Lefkada Island, Greece. Lefkada is close to the Cephalonia Transform Fault and has repeatedly experienced strong shaking in the past. The most recent event caused two fatalitites, some damage, and resulted in widespread environmental earthquake effects (EEE). A team of scientists visited the epicentral area after the quake and recorded the damage and the EEEs. They wrote a preliminary report, which can be downloaded here: Lefkada 17 Nov 2015 earthquake report (PDF, 3.9MB).

    They document mass movements, damage to buildings, and present first data from seismology, GPS and satellite geodesy.

    Thanks to George for sending us the report!

     

  • EEEs of today’s Mw6.5 earthquake in Greece

    A shallow Mw6.5 earthquake hit western Greece today in the morning. The quake had a right-lateral strike-slip mechanism and occurred at the Cephalonia transform, offshore Levkada. Two people died and some damage to buildings was reported. The event caused environmental earthquake effects (EEEs), namely widespread rockfalls that produced an amazing dust cloud. The blog North Ithaca has some great pictures of collapsed walls, damage to buildings and the dust cloud.

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  • Surface ruptures of the 1891 Nobi earthquake

    At the XIX INQUA congress in Japan I had the chance to see the surface ruptures of the 1891 Nobi earthquake during the mid-congress excursion M-2. This quake caused huge damage, but more interestingly for me, it produced amazing surface ruptures which are preserved even more than a hundred years after the event. The M7.5-M8 quake occurred in a mountainous area and was mainly strike-slip (more than 8 m!), but significant vertical uplift was found at step-overs. In 1991, the wonderful Neodani Fault Museum opened to the public, its main attraction being a paleoseismological trench exhibiting more than 5 m of vertical offset! Simply astonishing. Thanks to Atsumasa Okada, Heitaro Kaneda and Keitaro for this great excursion! more

  • Guest blog by Yu Zhou (Oxford): The 2013 Mw 7.7 Balochistan earthquake in Pakistan: NOT SO UNUSUAL

    In 2013, a MW7.7 earthquake struck Balochistan, caused a huge surface offset and triggered a small tsunami in the Arabian Sea. Immediately, the apparently strange fault behaviour caused the attention of scientists world wide and a number of papers were published. The discussion is highly interesting and still ongoing. This an interesting case for paleoseismologists, too, not only because of the cascading earthquake effects, but also because of the surface rupture distribution, from which we might learn some important lessons for our future work. Now my colleague Yu Zhou and his colleagues from Oxford University published a new paper on this event, arguing that it might be not as unusual as it seems. Their research is based on the analysis of Pleiades stereo satellite imagery, which has proven to be a very useful data source already. Yu send me a nice summary of his recent research: more

  • Italy’s Database of Individual Seismogenic Sources (DISS) v. 3.2.0 now online

    Great news from Italy – A new version of the Database of Individual Seismogenic Sources (DISS) is now online! A huge amount of work went into this latest release which has several important updates and a fantastic new amount of data. Our colleague Umberto Fracassi sent me the following description of the new features:

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  • Paleoseismology Through Sedimentology

    The Megablock Complex: An example from the East African Rift

    Recognizing and interpreting seismite horizons (soft-sediment deformation generated by earthquakes) preserved in the sedimentary record is an underappreciated approach for paleoseismic analysis. The addition of sedimentological studies to a toolkit that includes other well-established methods, such as instrumental seismic monitoring and fault trenching, can provide a less expensive and more practical option for earthquake hazard prediction and preparation in certain areas. For example, this may be a good option in less developed regions and in areas where fault trenching may not be possible. Moreover, there is a lot that we can learn rheologically from the study of seismites that could be invaluable for modeling the behavior of the surface/near-surface during seismic activity. Similarly, investigating Quaternary strata in areas that may be prone to seismicity, which may or may not have a recorded history of major earthquakes, can illuminate important information about earthquake recurrence patterns and intervals, in much the same way as fault trenching. more