[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”
The organisers of the PATA Days 2017 in New Zealand have provided details on the planned field trips. There will be a 1-day field trip at the start of meeting, and an optional 3-day post-meeting field trip. Some of the field trip details are not yet finalised because we don’t know the state of road access to some areas impacted by the Kaikoura earthquake. They will post a final itinerary in early November. Have a look at the programme and enjoy the magnificient field photos!
The city of Cusco in Perú has been hit by damaging earthquakes several times in its long history. In Inka times a strong earthquake destroyed parts of the city, and the Spanish invaders documented an earthquake that happened in 1650. Three hundred years later, in 1950, an earthquake destroyed large parts of modern Cusco and in 1986 a M6.1 event also led to damages in the city. In order to better understand the active normal faulting in the region, INGEMMET has launched the project Cusco-PATA (Paleoseismology, Archaeoseismology and Active Tectonics – “pata” also means “scarp” in Quechua). The project brings together scientists from Perú, Spain, France, and the UK. The 2017 field campaign started in mid-April with work on the archaeological sites in and around Cusco and paleoseismological trenching of the Pachatusan Fault. Continue reading “Active faults around Cusco (Perú): field work on paleoseismology and archaeoseismology for project Cusco-PATA”
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 .
For quite some time (~7 years), I have been noticing that Holocene Dead Sea seismites frequently have a thin dark flat lying fine grained layer of sediment on top. When I finally gained access to some electron microscopes at Cambridge University in 2013, I saw that these thin layers were very fine grained. After consultation with Dust Geologist Dr. Ken Pye, I came to the conclusion that they appeared to be proximal dust deposits. It was around that time that I realized that Dead Sea earthquakes probably kicked up dust clouds that then settled atop the seismite. An example of a dust cloud kicked up by an earthquake in Mexico is featured in my crowd funding pitch video (Jerusalem Quake Seasonality on Kickstarter ) and can be seen here (Mountain front dust clouds – Mexicali Quake of 2010 ). Christoph Gruetzner, who is also intrigued by the link between seismicity and dust, has accumulated a number of videos showing “dustquakes” on his YouTube channel. Continue reading “Using Dust and Pollen to sleuth the origin of lacustrine seismites”
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. Continue reading “The Great Wenchuan Earthquake eight years on: earthquake damage and coseismic landslides”
Our colleague Petra Jamšek Rupnik from the Geological Survey of Slovenia sent us this interesting meeting announcement. The conference will focus on geological hazards, including active tectonics in Croatia and adjacent areas. Plus, there will be an interesting field trip to Croatia and Slovenia: