Department of Civil Engineering

Indian Institute of Science, Bangalore

Seismic microzonation map

Deterministic seismic microzonation map

Deterministic seismic microzonation map is hazard index map for worst scenario earthquake. Important factor of PGA (weight is 9) is estimated from synthetic ground motions, which are generated based on MCE of 5.1 in moment magnitude for closest vulnerable source of Mandya- Channapatna- Bangalore lineament. Hazard index values are estimated based on normalized weights and ranks through the integration of all themes using the following equation:

 

 

Using estimated values deterministic seismic microzonation map has been generated. Figure shows the deterministic seismic microzonation map for Bangalore. Integrated GIS map shows that hazard index values vary from 0.10 to 0.66. These values are groped into four groups, <0.1, 0.10-0.15, 0.15-0.30, 0.3-0.45, 0.45-0.6 and 0.6 to 0.66. The maximum hazard is attached to the seismic hazard index greater than 0.6 at western part of Bangalore. Eastern part of city attached to a minimum hazard when compare to other areas. Western and southern part has mixed hazard and northern part has moderate hazard.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Probabilistic seismic microzonation map

Similar to DSM hazard index calculation, probabilistic hazard index has been estimated, but PGA values are taken from the probabilistic seismic hazard analysis. PGA at 10% probability of exceedance in 50 years has been estimated considering six seismogenic sources and regional recurrence relation. Based on probabilistic hazard index values probabilistic seismic microzonation map (PSM) has been generated. Probabilistic hazard index values are estimated based on normalized weights and ranks through the integration of all themes using the following equation:

 

 

 

Figure shows the probabilistic seismic microzonation map based on calculated hazard index. Probabilistic hazard index values vary from 0.10 to 0.66 and has been grouped to four such as <0.1, 0.10-0.15, 0.15-0.30, 0.3-0.45, 0.45-0.6 and 0.6 to 0.66. These values are lesser that deterministic hazard index. The maximum hazard is attached to the seismic hazard index greater than 0.6 at south western part of Bangalore. Lower part (south) of Bangalore is identified as moderate to maximum hazard when compared to the northern part.

 

 

 

 

 

 

 

 

 

 

Webpage is maintained by

Dr P Anbazhagan

Lecturer

Department of Civil Engg

Indian Institute of Science

Bangalore, India 560012

Suggestions and queries may be directed to Dr P Anbazhagan

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This page was last updated on August 25, 2011