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  • Ridgecrest & Searles Valley earthquakes: a fault displacement hazard analysis

    On July 4th and 5th, 2019 two earthquakes (Mw 6.4 and Mw 7.1, respectively) occurred in eastern California and produced distinct surface ruptures. Field surveys started immediately after the first event and, less than two weeks later, a provisional map of surface rupture was compiled and made available to everyone (Contributors from USGS, CGS, UNR, USC, CSUF). I downloaded the map and kmz files of the ruptures from the SCEC response site, which contains tons of fruitful information.

    The two strike-slip earthquakes ruptured two perpendicular faults, the first running NE-SW with left-lateral slip and the second running NW-SE with right-lateral slip (Figure 1). The location of the earthquake falls within the Eastern California shear zone, a region of distributed faulting associated with motion across the Pacific-North America plate boundary, and an area of high seismic hazard.

    Figure 1. Left: ground breaks caused by the 2 earthquakes. Right: simplified trace, used as main fault.

    Ruptures come with a variable degree of complexity: some sectors show a “simple” single strand, others show multiple sub-parallel or diverging splays. Distributed faulting represents displacements occurred off the principal fault and is generally made up by less continuous ruptures, which can be located tens of meters to a few kilometers from the principal fault trace. A method to evaluate the fault displacement hazard has been proposed by Youngs et al. (2003) and later refined by Petersen et al. (2011); the former study analyzed normal faults, while the latter analyzed strike-slip faults.

    Basically, the method defines the conditional probability of faulting occurrence as a function of distance from the principal fault and derives scaling relations between rupture probability and distance. I applied the same method on the 2019 sequence and compared the output with the results by Petersen; results are grid-dependent – since available data are still provisional, I used a quite coarse grid size of 200 m, more detailed studies will come.

    Results are in good agreement (Figure 2): the 2019 ruptures show a higher than average rupture probability at 0-2 km from the main fault, but also taper out faster than the previous events.

    Figure 2. Comparison between the 2019 events (blue: July 4th; red: July 5th) and data by Petersen et al. (empty circles). The probability of occurrence of faulting is plotted as a function of distance from the main fault (left: linear horizontal axis; right: logarithmic scale).


    Petersen, M. D., et al. (2011). Fault displacement hazard for strike-slip faults. BSSA, 101(2), 805-825.

    Youngs, R. R., et al. (2003). A methodology for probabilistic fault displacement hazard analysis (PFDHA). Earthquake Spectra, 19(1), 191-219.

  • PATA Days 2020 in Chile, 8-12 November – 1st circular

    The next INQUA meeting on Paleoseismology, Archaeoseismology, and Active Tectonics (PATA Days) will be held in Hornitos, Chile, from 8-12 November, 2020. Download the 1st circular here (PDF, 400 kb).

    See you all in Chile 2020!

  • International meeting in commemoration of the 20th Anniversary of the 1999 Marmara Earthquakes

    Dr. Gülsen Ucarkus send us the first circular for the following interesting meeting:

    We would like to invite you to the international meeting organized by Active Tectonics Research Group (ATAG) of Turkey in commemoration of 20th Anniversary of 1999 Marmara Earthquakes. Following these two devastating earthquakes (1999 Mw 7.4 İzmit and 1999 Mw 7.2 Düzce Earthquakes), a vast number of international/national projects carried out in the Marmara Sea region of Turkey and the outcomes of research done contributed significantly to multi-disciplinary studies in active tectonics. The meeting aims to revisit the results of these important number of observations together with new research going on to highlight the current state of seismic hazard in Marmara Sea where the next big earthquakes is expected to occur.

  • New papers on paleoseismology, earthquakes, and active tectonics (Feb 2019)

    New year, new science! These are the latest papers on paleoseismology, earthquakes, and active tectonics. Enjoy reading!


  • PhD and postdoc positions available at Pukyong National University, South Korea – active faults and seismic hazard

    These are great opportunities for PhD students and postdocs. A huge research programme in South Korea is now devoted to investigate the active faults of the country and to understand the seismic hazard, after two damaging earthquakes hit the country recently.

    Recruiting PhD Research Student and Postdoctoral Researcher

    Starting from March 2019, ‘The Korean Active Fault Research Group (KAFRG)’ and ‘The Institute of Active Fault and Earthquake Hazard Mitigation (IAFEHM)’ at Pukyong National University in South Korea are looking for competent and enthusiastic research students and geologists for PhD and Post-doc.

    Our research group and institute are currently leading active fault investigations and researches in South Korea. We also have been implementing collaborative researches with various domestic and overseas universities and research institutes. The ongoing main projects of our research group are ‘Investigation of active faults on the Korean Peninsula’ and ‘The safety evaluation for geological conditions and earthquake hazard for nuclear power plant sites and waste disposal facilities.’

    The initial employment – contract period is 1 year, and depending on the researcher’s achievement and contribution to the group the working year(s) can be extended. The annual salary will be arranged according to the researcher’s research experiences and the performances. more

  • PATA2018 Summer School: Special rates for students

    The #PATA18 workshop will be held from 25-27 June and the Summer School will take place on 28 June. Under- and post- graduate students can now attend both these events, with special rates:

    • Workshop (25-27 June): 30 Euros (attendance only)
    • Summer School (28 June): 30 Euros (attendance plus two meals)
    • Workshop + Summer School combo: 50 Euros.

    There is also the possibility to stay at the Aristotle University camping ground at a very low price, by bringing your own tent or renting one on site. To register for these events and for more information, please contact Ass. Prof. Alexandros Chatzipetros at no later than Jun 15th, 2018. more

  • New papers on paleoseismology, tsunami, and active tectonics (Jan 2018)

    I hope you’ve had a great start into the new year. A lot of new and exciting papers have been published at the end of the old one, including work on New Zealand and Europe. Enjoy reading and have fantastic new year 2018!


  • The Great Wenchuan Earthquake eight years on: earthquake damage and coseismic landslides

    Last October I was given the chance to attend the “iRALL school on field data collection, monitoring, and modeling of large landslides” in Chengdu, China. During the school, we spent one week in the epicentral area of the Ms=8.0 2008 Wenchuan earthquake, where I was able to take some interesting pictures of earthquake damage and coseismic landslides. Then other things happened, like the earthquakes in Italy and New Zealand, with exciting sights from the field shared here, and I never ended up sharing my Wenchuan pics, which I want to do now. more

  • Seismicity, Fault Rupture and Earthquake Hazards in Slowly Deforming Regions


    It’s a book!

    Sometimes, things need time to evolve. And when they finally arrive, all laborious work and cumulated frustration is almost immediately forgotten in a flash of joy, a little bit of pride, and a lot of relief. What sounds pretty pathetic here is a summary of the process that lead to the recent Geological Society of London Special Publication 432: Seismicity, Fault Rupture and Earthquake Hazards in Slowly Deforming Regions. While we will mostly advertise the volume, which should be of broad interest to the Paleoseismicity community (so please buy it, like it, share it!), we would also like to share some thoughts about why four years passed between submission of the volume proposal at the end of 2012 to seeing the book finally in the shelf at the beginning of 2017. more

  • New report by ISPRA et al. on field evidence of on-fault effects due to the Amatrice earthquake

    Lead by ISPRA, scientists from Italy, UK, and Norway have conducted field surveys and remote sensing to analyse the earthquake environmental effects of the 24 August, 2016, Amatrice Earthquake. The team has produced a 31-pages report that covers mainly field work results and INSAR data on ground deformation. Great photos of the surface ruptures! more