1) Microzonation main Volume - Ministry Of Earth Sciences

Deterministic Seismic Hazard Analysis10▲▲▲▲▲ 05▲▲▲▲ 01▲Gauribindanur Array ▲ 11▲(GBA)▲▲ ▲ 15▲▲22.4km▲▲20 NFigure 3.6: Pattern of the location of receivers in Gauribindanur Array.3.5 PREPARATION OF SEISMOTECTONIC MAP OF BANGALORESeismotectonic map showing the geology, geomorphology, water features, faults, lineaments, shear zone andpast earthquake events has been prepared for Bangalore which is as shown in Figure 3.7. Seismotectonic detailsof study area have been collected in a circular area having about 350 km radius around Bangalore. The sourcesidentified from SEISAT (2000) and remote sensing studies are compiled and a map has been prepared usingAdobe Illustrator version 9.0. The seismotectonic map contains 65 numbers of faults with length varying from9.73 km to 323.5km, 34 lineaments and 14 shear zones. The earthquake events collated and converted has beensuper imposed on base map with available latitudes and longitudes. The earthquake events collated are about1421 with minimum moment magnitude of 1.0 and a maximum of 6.2 and earthquake magnitudes are shown assymbols with different shape and colours. Maximum source magnitude is assigned based on the maximum sizeof the earthquake close to the each of the sources.3.6 GEOTECHNICAL DATA FOR ROCK DEPTHGeotechnical data was basically collated from geotechnical investigations carried out for several major projectsin Bangalore. The GIS model developed currently consists of about 850 borehole locations marked on thedigitized Bangalore map of 1:20000 scale which is shown in Figure 3.8. The data consists of visual soilclassification, standard penetration test results, ground water level, time during which test has been carried out,other physical and engineering properties of soil. Most investigations for residential and commercial complexeswere below 15m and wherever bedrock has been encountered investigation has been terminated at that depth forthese projects. This rock depth information has been used to prepare rock depth map for Bangalore, details arepresented in chapter 6. The rock depth information with latitude and longitude are obtained from the 653boreholes out of 850, which is used for rock level PGA Mapping. Further reduced level (RL) of each bore logrock depth is calculated from contour map (see the Figure 3.9.) developed in GIS model using TOPO sheets.Figure 3.9 shows the location of boreholes with the elevation contours at 10m intervals. The ground RL variesfrom 845 m to 910(mostly in the north and north western part of Bangalore, which gives information on slopingterrains or valleys and could be used to locate the RL of ground as well as rock surface.27