An overview on the seismic microzonation and site effect studies in Central Asia

Abstract

<p>During the past centuries, many cities in Central Asia have suffered significant damages caused by earthquakes. A crucial step towards preparedness for future events, the definition of the optimal engineering designs for civil structures and the mitigation of earthquake risks involves the accomplishment of site response studies. To accurately identify local variations of the site response at different locations within the cities, earthquakes recorded by seismic networks as well as measurements of the seismic noise can be used for estimating the resonance frequencies and for evaluating the expected level of ground motion at each site. Additionally, the measurements can help identifying site specific features like more-dimensional resonances and directional effects. This information can be complemented with array measurements of ambient seismic noise in order to estimate local shear-wave velocity profiles, an essential parameter for evaluating the dynamic properties of soil, and to characterize the corresponding sediment layers at each site. The present study gives an overview on the progressive development of the seismic zonation studies in the frame of EMCA carried out in several cities in Central Asia.</p>

Site Amplification Analysis of Dushanbe City Area, Tajikistan to Support Seismic Microzonation

“…Each seismogram provides data of three components. The standard spectral ratio method (SSR, see, e.g., [10,[22][23][24][25]67]) involves the comparison of earthquake recordings from nearby sites, using one of them as a reference. As a result, the standard spectral ratio can directly demonstrate the site effect.…”

“…For this reason, only non-invasive methods were used for data acquisition (Table 1): microtremor array measurements (MAMs), seismic refraction tomography (SRT), and instrumental data recording from temporary and permanent and from mobile seismic stations for long-and short-term acquisition, respectively. The use of these methods individually or in combination has proven to be successful for detailed seismic characterization and microzonation in the past (e.g., [10,[16][17][18][19][20][21][22][23][24][25][26]). The newly assessed data was combined with local geological and geotechnical data in the form of lithological maps and cross sections as well as borehole logs provided by the Head Institute of Engineering and Technical Surveys of the State Construction Committee of Tajikistan (HIETSCCT; [27]).…”

Assessing soil vulnerability in Petobo post-liquefaction zone, Palu, Central Sulawesi: A microzonation study utilizing microtremor measurements

“…Through the comprehension of these fluctuations, microzonation facilitates the attainment of enhanced precision in prognosticating ground response. Consequently, this contributes to the advancement of focused approaches for mitigating seismic risk and fostering resilient urban planning in regions susceptible to earthquakes (Fiorini et al, 2008;Pilz et al, 2015;Milutinovic et al, 2017;Karnaen et al, 2019;Zhang et al, 2022). The use of microzoning approaches in the Petobo region holds significant importance due to its past seismic activity and the need for tailored strategies to mitigate the distinctive ground susceptibilities in this locality.…”

Geocoding Applications for Social Science to Improve Earthquake Early Warning

“…Earthquake early warning (EEW) alerts are sent out based on magnitude and intensity thresholds. Geolocation is vital in determining seismic intensity, or the severity of earthquake shaking, as intensity varies by location on relatively small spatial scales (on the order of tens to hundreds of meters) due to microzonation (e.g., Kumar Shukla, 2022;Rastogi et al, 2023;Pilz et al, 2015). Seismic intensity impacts what an individual feels during earthquake shaking, whether they receive an earthquake early warning alert (or not), and whether a person takes a protective action (or not).…”