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Site Specific Seismic Hazard, Vulnerability, Risk and Damage Potential Modelling of Bangladesh With Seismic Hazard Microzonation for the Cities of Dhaka and Chittagong

Description: 

The riverine country of Bangladesh, located on the world’s largest fluvio-deltaic sedimentary basin, called unified Bengal Basin, is exposed to extreme seismic threats due to proximity to seismogenic blocks of the Northeast India, East-Central Himalaya, and the basin itself, also impinging many strong earthquakes in the past with MM Intensity of VIII-XI in near-source region. The thick Holocene alluvium covering the region can contribute to ground motion amplification and liquefaction effects, thus affirming the necessity of surface-consistent seismic hazard and risk assessments. Consideration of both areal and tectonic sources in three hypocentral depth ranges along with 14 ground motion prediction equations including 6 site-specific next generation spectral attenuation models has delivered Probabilistic Peak Ground Acceleration (PGA) at engineering bedrock ranging from 0.14-0.59g for 475years of return period. Geophysical and Geotechnical investigations at around 2200 sites yielded effective shear wave velocity in the range of 119-936m/s. Systematic nonlinear/equivalent linear site response analysis amplified the firm rock PGA by 1.06-4.05 times providing surface-consistent hazard in the range of 0.30-1.17g. Liquefaction Potential Index (LPI) using the estimated PGA places Dhaka, Mymensingh, Chittagong and Sylhet into “severe (LPI>15)” zone whereas in the Socio-Economic Risk Map, Dhaka and Chittagong are classified as “high to severe” category. Holistic Seismic Hazard Microzonation performed for the capital city of Dhaka and the Port City of Chittagong, integrating several geo-hazard and seismic hazard themes has microzoned the cities into four zones. Structural damage potential using SELENA-based Capacity Spectrum Method has been assessed for both the cities on eleven model building types in five damage states from ‘none’ to ‘complete’. Complete understanding of this comprehensive study is expected to guide city planners to provide seismic-resilient urbanization.

Session: Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict? [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Arpita Biswas

Student Presenter: Yes

Invited Presentation: 

Authors