Almaty sits on a huge active fault, and here is why we know

Almaty, the former capital of Kazakhstan and home to ~2 million people, is a rapidly growing, vibrant city, beautifully situated at the foothills of the mighty Zailisky Alatau, the northernmost mountain range of the Tien Shan at this longitude. The city sits on a huge alluvial fan with the snow-capped mountains in the background, reaching 5,000 m elevation. Almaty has suffered from earthquakes in its young history: in 1887, the Verny earthquake with a magnitude of about 7.3 had its epicentre a few kilometres west of the city but did not produce surface ruptures (Verny is the old name of Almaty). Only two years later, the M8 Chilik earthquake ruptured the surface 100 km to the southeast of Almaty. Finally, Almaty was heavily damaged by the 1911 Chon Kemin earthquake with a magnitude of ~8, which occurred on the southern flank of the Zailisky Alatau. In our new paper we now report on a fault that did not rupture in historical times, but surely did so in the Holocene – and this fault is right beneath the city. Continue reading “Almaty sits on a huge active fault, and here is why we know”

Studying the earthquake geology of the Chilik-Chon Kemin Fault Zone in Kazakhstan

The Chilik-Chon Kemin Fault Zone is a major left-lateral strike-slip fault zone in Kazakhstan and Kyrgyzstan, just a few tens of kilometres east of Almaty and north of Lake Issyk Kul. It has seen one of the largest continental earthquakes ever recorded in 1889, with an estimated magnitude of ~M8.3. In July and August I had the chance to visit this fault zone for two weeks together with Angela Landgraf from Potsdam and Aidyn Mukambaev from the National Data Centre, thanks to a travel grant from COMET (thanks so much, COMET!) and with support from the EwF Project. We wanted to find out more details about the tectonic geomorphology of this fault zone and we wanted to study the slip rate and earthquake recurrence intervals. So we took our drone, shovels and picks and set off for a field trip into the mountainous wilderness. Since I will leave for another field trip to Kazakhstan (Dzhungarian Fault) tomorrow, I will leave you with some impressions from our field work and provide more information once the paper is published…
Enjoy!  Continue reading “Studying the earthquake geology of the Chilik-Chon Kemin Fault Zone in Kazakhstan”

New papers on paleoseismology in the Tien Shan

Between 1885 and 1938, the northern Tien Shan at the border between present Kyrgyzstan and Kazakhstan experienced a remarkable series of five major earthquakes, exceeding M6.9 and reaching up to M ~ 8 (1885 Belovodskoe M6.9, 1887 Verny M7.3, 1889 Chilik M~8, 1911 Chon Kemin M8, and 1938 Kemino Chu M6.9). Combined, the seismic moments add up to almost moment magnitude 9, which is a significant amount of strain released in roughly 50 years and across an E-W stretch of less than 500 kilometers. Even more intriguing is the fact that the ruptured region is located more than thousand km north of the nearest plate boundary and associated India-Eurasia collision zone. The macroseismic areas of these earthquakes include the present-day capital of Kyrgyzstan, Bishkek (Frunze) and the former capital and still largest city of Kazakhstan, Almaty (earlier names Alma Ata and Verny).
Continue reading “New papers on paleoseismology in the Tien Shan”

This was my field work on active faults in Kazakhstan 2015 (pt. II)

The first part of my report on the field work that I did in Kazakhstan this year focussed on the stuff we had done in the South. Here is part II which is all about the Dzhungarian Fault. You’ve never heard about this fault? That’s easily possible. There are only very few papers that deal with this fault. In the 1960s Soviet geologist V.S. Voytovich published results from extensive field work on this fault (Voytovich, 1965; 1969). 40-50 years later a few studies on geodesy and geodynamics covered the broader study area and Shen et al. (2003) did some work in the Chinese part of the fault, but it took until 2013 before Campbell et al. revisited the Kazakh side and came up with new field data. They focussed on the tectonic geomorphology of this structure and determined a slip rate. Given this little amount of research done one would assume that the fault is not very large and of minor importance, but the opposite is true. The fault is around 300 km long in its Kazakh section and probably twice as long in total! Continue reading “This was my field work on active faults in Kazakhstan 2015 (pt. II)”

This was my field work on active faults in Kazakhstan 2015 (pt. I)

I’ve spent several weeks in Eastern Kazakhstan this summer for paleoseismological field work. During the first part of this trip we looked at some thrust and strike-slip faults in the Ili Basin and the Saty area. The second part was almost entirely devoted to study the Dzhungarian Fault. I’ll blog about this second part later. Eleanor, David, Austin and me were the UK representatives in our team. We were so lucky to have Kanatbek from Kyrgyzstan and Aydin from Kazakhstan with us. They did not only lead us to all the interesting places and helped us to understand the geology and the tectonics, but they also did a fanatastic job organizing the field trip and dealing with the local surprises, which as you know happen in basically every field trip.

Our first study site was located at the northern boundary of the Ili Basin, where we did some work last year already. Continue reading “This was my field work on active faults in Kazakhstan 2015 (pt. I)”

Literature update

Lots of paleoseismology and tsunami studies are currently being published… Here’s my update on the latest papers, including: Surface ruptures, seismic swarms, tsunamites, Asian tectonics, slip rates and archaeoseismology. Plus: A very interesting study on the 1911 Chon-Kemin M8.0 earthquake in the Kazakhstan/Kyrgyzstan border region, the source process reconstruced from analogue seismograms. Thanks to Ramon Arrowsmith for pointing me to this one. Enjoy!

Continue reading “Literature update”

Paleoseismological field work in Kazakhstan

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During the last three weeks I have been to Kazakhstan for paleoseismological field work and to summarize this journey: It was amazing! The trip was part of the Earthquakes without Frontiers project (EwF). This research project is funded by NERC and ESRC and aims on increasing the knowledge on earthquake hazards in Central Asia. The field work was lead by Richard Walker and scientists from Kazakhstan, Kyrgyzstan, and the UK had a close look at fault scarps in the easternmost parts of the country. Our aim was to determine the slip rates of some of the longest and most prominent thrust and strike-slip faults in the area. Continue reading “Paleoseismological field work in Kazakhstan”