The Hokudan 2020 International Symposium on Active Faulting will take place from 13-17 January in Awaji City, Awaji Island, Japan. The symposium is held every five years. The 2020 event commemorates the 25th anniversary of the 1995 Kobe earthquake. All important information on this meeting is available here: https://home.hiroshima-u.ac.jp/kojiok/hokudan2020.html
This event is supported by INQUA – the International Union for Quaternary Research and its TERPRO commission. For more information, please contact Koji Okumura (kojiok@hiroshima-u.ac.jp) or Shinji Toda (toda@irides.tohoku.ac.jp).
Press note related to the publication of the manuscript “Earthquake crisis unveils the growth of an incipient continental fault system” in Nature Communications (DOI: 10.1038/s41467-019-11064-5).
An international team led by the Institut de Ciències del Mar (ICM-CSIC, Barcelona) demonstrate the growth of a young fault in the Alboran Sea, called the Al-Idrissi Fault System, source of the magnitude (Mw) 6.4 earthquake, which affected Al-Hoceima, Melilla and the south of the Iberian Peninsula in January 2016.
The mega-hot summer seems to be finally over (at least in Germany), and most of this season’s field work is probably done. So why not catch up with the latest papers on paleoseismology and related subjects? These are the latest papers:
The Department of Earth Sciences at the University of Oxford is currently recruiting a PDRA in Active Tectonics Research:
We seek to appoint a Postdoctoral Research Assistant to work closely with Professor Richard Walker as part of a broader consortium in the NERC-funded ‘Looking Into the Continents from Space’ project, whose principal aim is to provide insights into earthquake hazard and crustal deformation through the application of a range of remote-sensing, field-based, seismological, and modelling approaches. The post is co-funded by COMET, which is a world-leading centre for understanding tectonic and volcanic processes and hazards (comet.nerc.ac.uk). The PDRA will join a thriving group involved in remote-sensing and field-based research in the study of active faulting and natural hazards. The post is based in the Department of Earth Sciences and will be overseen by Richard Walker, Barry Parsons and Philip England. The post will also involve close collaboration with scientists at the other partner institutions involved in COMET and LICS. The successful applicant will be responsible for the mapping and analysis of fault-based geomorphology using high-resolution satellite imagery and digital topography, supplemented with fieldwork in selected regions. The production of high-resolution digital topographic datasets through field-based, aerial, or satellite methods, forms an important component of the duties. They will also be expected to possess or to develop skills in measuring surface displacements through the matching of optical satellite imagery, and to support both tectonic and volcanic applications of high-resolution imagery and elevation data throughout COMET
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).
References:
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.
This month’s list of papers includes a lot of work on (Central) Asia, New Zealand, and also some nice tsunami stories. Enjoy reading and – as always – please tell us in case we’ve missed something.
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).
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.
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