Day 4

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Paper title Improving urban seismic risk estimates for the major cities of Bishkek (Kyrgyzstan) & Almaty (Kazakhstan) using EO data
Authors
  1. John Elliott COMET, University of Leeds Speaker
  2. Ruth Amey University of Leeds
  3. Scott Watson COMET, University of Leeds
  4. Kanatbek Abdrakhmatov Institute of Seismology
  5. Richard Walker Oxford University
  6. Ekbal Hussain British Geological Survey
  7. Marco Pagani GEM Foundation
  8. Vitor Silva GEM Foundation
  9. Sultan Baikulov Institute of Seismology, Bishkek
  10. Gulkaiyr Tilek Kyzy Institute of Seismology, Bishkek
Form of presentation Poster
Topics
  • D1. Managing Risks
    • D1.01 Satellite EO for Geohazard Risks
Abstract text Many cities are built on or near active faults, which pose seismic hazard and risk to the urban population. This risk is exacerbated by city expansion, which may obscure signs of active faulting. Here we estimate the risk to two major capital cities along the northern Tien Shan. Bishkek is the capital of Kyrgyzstan with a population just under one million and Almaty is Kazakhstan’s largest city with over 2 million inhabitants. Major faults of the Tien Shan, Central Asia, have long repeat times, but fail in large (Mw 7+) earthquakes. In addition, there may be smaller, buried faults off the major faults that are not properly characterized or even recognized as active. These all pose hazard to cities along the mountain range front. We explore the seismic hazard and risk for these pair of major cities from devising a suite of realistic earthquake scenarios based on historic earthquakes in the region and improved knowledge of the active faulting. We use previous literature and fault mapping, combined with new high-resolution digital elevation models to identify and characterise faults that pose a risk to the cities. By making high-resolution Digital Elevation Models (DEMs) from SPOT and Pleiades stereo optical satellite imagery, we identify fault splays near and under Almaty. We assess the feasibility of using DEMs to estimate city building heights, aiming to better constrain future exposure datasets. Both Pleiades and SPOT-derived DEMs find accurate building heights of the majority of sampled buildings within error. For Bishkek, we model historical events and hypothetical events on a variety of faults that could plausibly host significant earthquakes. This includes proximal, recognised, faults as well as a fault under folding in the north of the city that we identify using satellite DEMs. We then estimate the hazard (ground shaking), damage to residential buildings and losses (economical cost and fatalities) using the Global Earthquake Model OpenQuake engine. In both cases, we find that even moderately sized earthquake ruptures on faults running along or beneath the cities have the potential to damage ten thousand buildings and cause many thousands of fatalities. This highlights the importance of characterizing location, extent, geometry, and activity of small faults beneath cities.