Speaker
Dr
Aida Azari Sisi
(BGR)
Description
Different geo-hazards are investigated in the framework of the German-Bangladesh technical cooperation project: “Geo Information for Urban Planning and Adaptation to Climate Change (GPAC)". Seismic hazard assessment is one focus of the project. Bangladesh is located close to the boundaries of the complex convergence of Indian and Eurasian plates to the north and to the east. These collision and subduction processes have caused large historical earthquakes also intraplate in Bangladesh (e.g.: 1885 Bengal Earthquake M7 and 1918 Srimangal Earthquake M7.6). Therefore, it is crucial to assess seismic hazard which then will be considered in urban planning of Bangladesh.
Compilations of faults derived from classical tectonic analyses indicate that most of the active faults are located in the northern and eastern boundaries of Bangladesh as expected. The recurrence parameters and maximum magnitudes of some of the active faults are derived by paleoseismic investigations.
Like in other countries, the earthquake catalog of Bangladesh is structured according to the use of modern instruments from 1963, the use of early instrumentation from 1900 on and collections of historical macro-seismic data. However, due to the sparse seismic network with only few stations on deep sedimentary basins, the detection threshold for intraplate seismic events is high compared to regions like Europe or China. Also only few historical seismic events were documented before 1900. Hence, completeness of the catalogue as a function of magnitude and time as well as clustering of events are significant properties to be taken into account for seismic hazard assessment. These two features and their effect on magnitude-frequency relationships are explored in the case of the earthquake catalog of Bangladesh.
Based on a spatial analysis of the existing data mentioned above the distribution of seismic sources is derived (seismotectonic zones as well as single identified faults) which is another important input to seismic hazard assessment.
Primary author
Dr
Aida Azari Sisi
(BGR)
Co-authors
Dr
Diethelm Kaiser
(Federal Institute for Geosciences and Natural Resources (BGR))
Dr
Jörg Schlittenhardt
(BGR)
Dr
Thomas Spies
(BGR)
