Categories
webinar

COMET Webinar by Ruth Amey : “Using Satellites to Inform Seismic Hazard and Risk Estimates in Central Asia”

A very interesting webinar will be held on Wednesday, 20th October, 4pm UK / 5pm CEST / 8am PDT in the COMET Webinar series. Ruth Amey from the University of Leeds will talk about the use of satellite technology for seismic hazard studies in Central Asia. The webinar is free, but requires registration here.

Also check out the earlier talks in the COMET webinar series here: https://comet.nerc.ac.uk/!

Categories
webinar

Online Webinar by Kathryn Fitzsimmons on 25 Oct, 2021: What goes on between the mountains and the deserts?

In the framework of our NATO-funded project SPS G5690 – “Earthquake Hazard and Environmental Security in Kazakhstan and Kyrgyzstan” we will run an ~1 hr online webinar. Kathryn Fitzsimmons from the University of Tübingen will talk about What goes on between the mountains and the deserts? A sedimentary view of past environments along the Tien Shan piedmont. The webinar is open for everyone interested and will be held via zoom (https://uni-jena-de.zoom.us/j/8941887790 Meeting-ID: 894 188 7790; Password: EQAsia).

Date: 25 October, 2021

Time: 3 pm UK time (3 pm London; 4 pm Berlin & Paris; 10 pm Beijing; 7 am San Francisco)

Categories
research updates

New paper on the seismic hazard in Almaty by Amey et al.

Our team has published a new paper on the seismic hazard in the Almaty region, Kazakhstan. We use high resolution satellite imagery to map faults around Almaty, Kazakhstan, and then use GEM’s OpenQuake to calculate shaking, damage and losses to the city from earthquake scenarios. Here’s what we found.

This is a Google Earth image of Almaty city, looking ~south. This has 3x vertical exaggeration – Almaty city is ~700 m elevation, and those snow-topped peaks are 4000 m. Many cities grow near mountains because of the protection, but these mountains are formed by earthquakes.

Almaty has been damaged by large earthquakes in the past, including 1887 (Verny, magnitude ~7.3), 1889 (Chilik, Mw ~8.0) and 1911 (Chon-Kemin, Mw ~8.0). So big earthquakes happen here. But Almaty has grown in size significantly since these last events, and has now ~ 2 million residents.

And earthquakes don’t just occur in the mountains. Earthquakes happen on faults, and sometimes these faults at the base of mountains can ‘step’ from the edge of the mountains into the basins. So potentially Almaty could be built on faults which are now hidden by the city.

This is where high-resolution satellite imagery comes in. Satellite ‘digital elevation models’ give the ground height. ~30 m resolution images can map big faults at the edge of mountains, but to map small, subtle faults hidden by a city we need higher resolution, ~2 metres.

In this paper we use pairs of optical satellite images (Pléiades + SPOT), taken of the same location but at different angles. Using these angles we can calculate elevation across the whole image. At 2 m resolution we see buildings + trees.

Using high-resolution maps of height, we look if there are places where faults have lifted the ground, under the city. A fault in Almaty has been identified before (Paper by Grützner et al., 2017). It has lifted the street up, and the same thing can be seen on parallel streets.

We also use TanDEM-X data (12 m) to map folding north of Almaty. From the shape of the fault, if there were a fault causing this folding it would dip south. Meaning that lots of the city would be directly above the fault.

Earthquake scenarios

We identify a number of plausible earthquakes that might cause damage to Almaty. This map shows what we think they might be – with the surface in red and the fault at depth in blue (faults aren’t really rectangular like this, but we use simple models):

The OpenQuake Engineuses fault geometry, size of the earthquake, ground info, as well as building information (the number, material, height, occupants, cost). Then it calculates ground motion, damage, and losses that might occur uses ground motion prediction equations.

Earthquake consequences

Using our input earthquakes, here is the shaking that Almaty would experience:

Here are the number of completely damaged buildings:

Here is the economic cost of replacing buildings:

And this would be the fatalities (which really shows how serious earthquakes would be for Almaty):

This shows earthquakes close to the city, even if they are much smaller magnitude than those far away, can cause a lot more damage and loss to Almaty. The worst scenario we model is the northern fault, which could cause ~12,300 completely damaged buildings and ~4,100 fatalities.

Also, we can use satellite estimates of elevation to calculate building heights, which can potentially help us do earthquake loss calculations. Long story short – we can get building height estimates, there are sometimes some problems and it’s better with higher resolution DEMs.

Key points

  1. Digital elevation models derived from high-resolution satellite imagery can map active faulting near cities and determine building heights.
  2. Our earthquake scenario risk calculations show a moderate earthquake on a fault in north Almaty would cause considerable damages (building collapses) and loss (economic and fatalities) due to how close it is to the city.
  3. It’s really important to properly characterise fault location and geometry close to cities in order to work out the relative level of seismic hazard and risk.

We have lots to do to make cities more resilient to earthquakes! So please read our paper:

Amey, R. M., Elliott, J. R., Hussain, E., Walker, R., Pagani, M., Silva, V., … & Watson, C. S. (2021). Significant Seismic Risk Potential from Buried Faults Beneath Almaty City, Kazakhstan, revealed from high‐resolution satellite DEMs. Earth and Space Science, e2021EA001664.

We’re happy to discuss further, either in the comments below or via email, Twitter, or – even better – in person.

References and further reading

Categories
webinar

Video: Talk by Marc Jolivet about the Mesozoic and Cenozoic evolution of the Tien Shan

On 28 June, 2021, Marc Jolivet from Geosciences Rennes gave the third talk of our lecture series on the tectonics of Central Asia. The topic was The Mesozoic and Cenozoic tectonic, topographic, and climate evolution of the Tian Shan region: an insight from geomorphology and sediment analysis. In case you missed Marc’s presentation, here’s the video.

Watch this space for future talks, always on the last Monday of every second month, and follow us on Twitter for updates: https://twitter.com/QuakesCentAsia

Categories
webinar

Online Webinar by Marc Jolivet on 28 June, 2021: The Mesozoic and Cenozoic tectonic, topographic, and climate evolution of the Tian Shan region: an insight from geomorphology and sediment analysis.

In the framework of our NATO-funded project SPS G5690 – “Earthquake Hazard and Environmental Security in Kazakhstan and Kyrgyzstan” we will run an ~1 hr online webinar. Marc Jolivet from Geosciences Rennes will talk about The Mesozoic and Cenozoic tectonic, topographic, and climate evolution of the Tian Shan region: an insight from geomorphology and sediment analysis. The webinar is open for everyone interested and will be held via zoom (https://uni-jena-de.zoom.us/j/8941887790 Meeting-ID: 894 188 7790; Password: EQAsia).

Date: 28 June, 2021

Time: 3 pm UK time (3 pm London; 4 pm Berlin & Paris; 10 pm Beijing; 7 am San Francisco)

Categories
webinar

Video: Talk by Sabrina Metzger on “Recent kinematics of the Greater Pamir based on GNSS and InSAR data”

On 26 April, 2021, Sabrina Metzger (GFZ Potsdam) gave the second talk of our lecture series on the tectonics of Central Asia. In case you missed Sabrina’s presentation, here’s the video.

Watch this space for future talks, always on the last Monday of every second month, and follow us on Twitter for updates: https://twitter.com/QuakesCentAsia

Categories
webinar

Online webinar by Sabrina Metzger on 26 April, 2021: Recent kinematics of the Greater Pamir based on GNSS and InSAR data

In the framework of our NATO-funded project SPS G5690 – “Earthquake Hazard and Environmental Security in Kazakhstan and Kyrgyzstan” we will run an ~1 hr online webinar. Sabrina Metzger from GFZ Potsdam, Division of Lithosphere Dynamics, will talk about Recent kinematics of the Greater Pamir based on GNSS and InSAR data. The webinar is open for everyone interested and will be held via zoom (https://uni-jena-de.zoom.us/j/8941887790 Meeting-ID: 894 188 7790; Password: EQAsia).

Date: 26 April, 2021

Time: 3 pm UK time (3 pm London; 4 pm Berlin & Paris; 10 pm Beijing; 7 am San Francisco)

Categories
webinar

Video: Talk by Ray Weldon on “How better geology can improve seismic hazard estimates in Kyrgyzstan”

On 22 Feb, 2021, Ray Weldon (University of Oregon) opened our public lecture series on the tectonics of Central Asia. More than 100 participants from all over the world tuned in. From now on, we will have a public lecture every two months. In case you missed Ray’s presentation, here’s the video.

Watch this space for future talks, always on the last Monday of every second month, and follow us on Twitter for updates: https://twitter.com/QuakesCentAsia

Categories
webinar

Online webinar by Ray Weldon & Kanatbek Abdrakhmatov on 22 Feb 2021: How better geology can improve seismic hazard estimates in Kyrgyzstan

In the framework of our NATO-funded project SPS G5690 – “Earthquake Hazard and Environmental Security in Kazakhstan and Kyrgyzstan” we will run an ~1 hr online webinar. Ray Weldon from University of Oregon will talk about How better geology can improve seismic hazard estimates in Kyrgyzstan. The webinar is open for everyone interested and will be held via zoom (https://uni-jena-de.zoom.us/j/8941887790 Meeting-ID: 894 188 7790; Password: 820815).

Date: 22 February, 2021

Time: 3 pm GMT (3 pm London; 4 pm Berlin & Paris; 11 pm Beijing; 7 am San Francisco)