[UPDATE 2017-05-14: The links now lead to the free version of the paper, available until 30 June.]
Together with my colleagues I have published a new paper in which we describe a methodology for mapping the shallow architecture of large sedimentary basins with minimum effort and high resolution. We use two geophysical methods and combine them with point information from shallow drillings to identify different types of alluvial, fluvial, and aeolian sediments in the Orkhon Valley in Mongolia. We then show that our results fit well with a remote sensing approach. Although we did not target active faults in our study, the methodology is well suitable for detecting deformed/offset sediments without surface expression due to high erosion or sedimentation rates. That’s why I feel the study is of interest for the fault-hunting community. Continue reading “Paper: Using georadar and a mobile geoelectrics device to map shallow sediment distribution on a large scale”
In 2003 a devastating Mw 6.6 earthquake shook the city of Bam in the remote Kerman region of SE Iran, killing at least 31,000 people. This was one of the most destructive earthquakes on record in Iran, and racked up the fifth largest death toll of any earthquake since the year 2000. This blog post will focus on highlighting research which shows that even after this awful natural disaster, the hazard posed by faults in the area is likely to have remained high, contrary to many common assumptions.
Immediately following the Bam earthquake scientists scrambled to map the housing damage, surface fractures, aftershock patterns and co-seismic deformation to better understand the earthquake source . One such study found that the structure responsible for the extreme shaking at Bam was a previously unrecognised near-vertical strike-slip fault directly beneath the city, which ruptured between 2-8 km depth . However, accurate aftershock locations suggested that the fault zone could generate earthquakes well below the base of the 2003 rupture patch, to nearly 20 km depth .
The observation that only part of the seismogenic layer at Bam had ruptured in 2003 posed a series of important questions for the future seismic hazard in this already fragile region:
(1) Will post-seismic deformation mechanisms relax the stress changes generated by the 2003 earthquake on the fault surface aseismically?
(2) What is the future seismic hazard at Bam?
In a recent paper published in Geophysical Journal International, we have addressed these questions, as well as other topics of academic interest, by studying the post-seismic deformation after the Bam earthquake .
Our colleague Lucilla Benedetti (CEREGE, France) distributed the following call for papers on the recent earthquake series in Central Italy:
We would like to invite contributions to a special volume entitled « The 2016 Central Italy Seismic Sequence: Insights, implications and lessons learned » that will be published in Tectonics AGU journal (details here).
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. Continue reading “Seismicity, Fault Rupture and Earthquake Hazards in Slowly Deforming Regions”
In microtidal seas such as the Mediterranean (tidal range ≈0.4 m sea-level indicators are commonly used to infer coseismic history. A list containing these indicators is long, including wave-cut platforms, marine terraces, displaced beach rock, biological agents, sedimentological and stratigraphical indicators, and archaeological indicators. Obviously, the trustworthiness varies a lot from one to another. For deriving late Holocene coastal tectonic activity, one of the most commonly used sea-level marker activity are tidal notches. These form distinct morphological and ecological erosional features developed within the tidal range [Pirazzoli, 1986; Antonioli et al., 2015]. Continue reading “From coastal earthquake geology and semi-automated feature detection”