Poster #055, Earthquake Engineering Implementation Interface (EEII)

Tectonic and Geotechnical Review for Engineering Design and Seismic Risk Management in Bangladesh

Mir F. Karim, MD Zillur Rahman, Arif M. Sikder, & Daya Shanker
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Poster Presentation

2021 SCEC Annual Meeting, Poster #055, SCEC Contribution #11558 VIEW PDF
Bengal basin is a classic and active natural laboratory due to its complex geological-setting and building up of an active depositional basin in a syntaxis of multidimensional differential stress conditions resulting from the relative motion of three tectonic plates. The earthquake risks in Bangladesh (a greater part of Bengal Basin and engulfed in NE India) are poorly predicted due to relevant geological information owing to the insufficiency of representative and instrumental seismic data acquisition systems.

An attempt is made here to standardize the engineering geological parameters in regards to the right earthquake magnitudes including intensity responses for determini...
ng design parameters based on available geological, gravity, magnetic data and reflection seismic profiles along with detailed fieldwork. For a rational seismic risk assessment it is necessary to identify and map of seismogenic zones (including the distals), their dimensions, historical events (here Max Mag 7.2), the type of source area and geotechnical ground response criteria. The ranges Peak Ground Acceleration and Amplification Factors are correlated for geological units.

Three types of earthquake source areas are identified: a. Intra-plate source areas, b. Transitional source area and c. Inter-plate source area. The seismic behavior of these source areas is deeply related to the tectonic pattern and crustal configuration of the basin. The Basin is divided into five major geotechnical provinces: 1. Continental slope along Hinge Zone, 2. Stable shelf, 3. Deep central trough (Sylhet-Hatiya), 4. Chittagong-Tripura fold belt to the east and 5. Dauki Fault Zone.

The local ground condition and geomorphological attributes are responsible for seismic spectral response patterns from actual point, area and volume of seismic sources; and are mapped in accordance to the geological structural, geotechnical index classification of deposits, strength and settlement characteristics to aid assessment of prompted response spectrum and appropriate safety factors. These parameters will intelligently aid the enhancement of Building Codes of the region.