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
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!
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.
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
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
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:
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
It’s Friday – but instead of the Friday links I have the story of a giant post earthquake debris flow in the Wenchuan area for you. As I already announced in my last post about the field trip to the Wenchuan earthquake epicenter in frame of the International Symposium on Mega-Earthquake Induced Geo-disasters and Long Term Effects in Chengdu, China, I still wanted to blog about the Qipan gully debris flow that we also visited during the field trip. After giving you some background information I will take you on the hike with us. We will first see massive destruction in the residential area and then have a look at the debris flow deposits and some mitigation structures while climbing up the gully. Come on, let’s go! more
In my last post I blogged about the International Symposium on Mega Earthquake Induced Geo-disasters and Long Term Effects in Chengdu, China, and now I want to report about one of the field trips that I participated after the symposium. While we spent the morning and early afternoon at the Qipan gully to look at a giant debris flow that occurred five years after the earthquake, in the afternoon we had the chance to visit the memorial site of the 2008 Mw 7.9 Wenchuan earthquake, which is basically the collapsed building of a middle school close to the epicenter that was left as it was after the earthquake. I want to report about this site first because it is more about the earthquake itself. In my next post I will report about the Qipan gully debris flow. more
Earthquake Environmental Effects (EEE) have proven to be valuable for describing past earthquakes and their geological imprints. The ESI2007 is a relatively new intensity scale dedicated to such effects, but also integrating traditional macroseismic scales. Examples of ESI2007 intensities assigned to large earthquakes are being collected in the EEE web catalogue hosted by the ISPRA and ESI2007-related work is conducted in the framework of INQUA.
Another milestone now has been achieved with the ISPRA volume “Earthquake Environmental Effect for seismic hazard assessment: the ESI intensity scale and the EEE Catalogue”. This book is now available online here. It contains updates on the ESI2007, examples of applications, documentation of the EEE Android App, a huge reference list and, most importantly, the ESI2007 description in ten languages: more