Earthquakes do not elucidate an entire fault-zone structure in the near surface; it is difficult to assess the overall tectonic structure from seismicity alone (Catchings et al., 2015). Journal of Geophysical Research 120 (5): 3479–3506. Aditya, and A. Gupta. Kale, V.S., Survase, V. and Upasani, D., 2014. Tectonophysics 213 (3–4): 367–374. India has witnessed a number of devastating earthquakes in the past five decades. Seismic hazard analysis for the Bangalore region. Regional geomorphic features such as valleys and steep slope hilly landforms — forming high relief terrain can alter the direction of propagating seismic waves. 1977. Journal of Earth System Science 117: 809–831. Geoenvironmental Disasters Considering the seismic risk and economic losses, seismic microzonation and hazard assessment at regular interval should entail as a part of disaster management processes for mitigating the hazard. Steep terrain slope tends to focus the reflected seismic waves at the slope crest, whereas gentle slopes scatter the diffracted seismic wave (Ashford et al., 1997). Cookies policy. At the same time, towns situated in proximity to urban areas are being developed to decongest the cities. (Fig. Ramana, D.V., R.K. Chadha, C. Singh, and M. Shekar. Using ArcGIS® estimated PGA-values gridded data are interpolated by means of geostatistical Kriging method to obtain the spatial distribution of hazard levels. Geologists, basing their opinion on this information, have suggested that the earthquake resulted from movements along a fault, possibly a satellite of the principal fault along the Malabar coast, and that it may be an isolated event unconnected with the reservoir and the earlier seismic activity. 3 and 6). The magnitude 6.6 shock hit with a maximum Mercalli intensity of VIII (Severe). This Shield area was described as the stable land mass associated with low or no seismicity. Engineering Geology 10: 123–150. The 1967 Koynanagar earthquake occurred near Koynanagar town in Maharashtra, India on 11 December local time.The magnitude 6.6 shock hit with a maximum Mercalli intensity of VIII (Severe).It occurred near the site of Koyna dam, raising questions about induced seismicity, and claimed at least 177 lives and injured over 2,200. Fault-plane solutions and allied geophysical modelling have yielded results that are not consistent with each other. For hazard estimation, seismic events are collated till early 2017 and total hazard from the five linear sources are presented as spatial distribution of PGA and hazard potentials. volume 217, pages1138–1139(1968)Cite this article. Toro, G.R., 2002. where Y = PGA, y Some geologists believe that the earthquake was due to reservoir-triggered seismic activity,[4] but senior project officials have repeatedly denied this conclusion. A magnetotelluric (MT) study across the Koyna seismic zone, western India: Evidence for block structure. There are more than 11 volcanic flow basalt layers and they consist of massive and vesicular basalt, amygdaloidal basalt, agglomerate, tuff breccia and red bole. 2008. Topographic effects on the seismic response of steep slopes. Chandra, U. Van Westen. The micro-earthquake activity close to the source region was found to increase before the occurrence of the main shocks and continue up to a month before reaching a background level (Ramana et al., 2007). Earthquake ground shaking varies from place to place and it depends on the properties of the rocks and weathered or soil column that earthquake waves travel through. In addition to NNW-SSE, N100E to N300E lineaments are also present. SRTM data having three arc-second (~90 m) ground resolutions is used to produce the spatial distribution of elevation and slope. The event was initially attributed to reservoir-induced seismicity. (2018), Bulletin of the Seismological Society of America The depth of focus of the earthquake has been estimated at about 30 km. The annual rates of PGA-values (10% exceedance probability) are calculated for around 300 point locations which make up the grid of 10 Km X 10 Km covering entire study area and its surroundings. Seismic risk and damage potential can modify with the occurrence of fresh events. Cite this article. There is a lack of evidence of block-faulting as the Western Ghats escarpment is well-adjusted to rock type and crustal structure (Fig. (2018), Journal of Seismology Estimated PGA-values are grouped into three categories that are relatively defined as high, moderate, and low hazard zones, respectively. Scientific Drilling 12: 53–54. Nath, and I. Pal. 0 Gupta, H., S. Nayak, and the Koyna Workshop Committee. Spatial distribution of estimated PGA (% g) as hazard levels and MMI –VII as damage potentials in 50 years. Location of Koyna region and the Peninsular India. Rao, N.P., Kumar, M.R., Seshunarayana, T., Shukla, A.K., Suresh, G., Pandey, Y., Raju, D., Pimprikar, S.D., Das, C., Gahalaut, K., Mishra, P.S., and Gupta, H. 2011. THE Koyna earthquake of December 11, 1967, killed about 200 people and injured a few thousand. Get the most important science stories of the day, free in your inbox. Geo-referenced information could be retrieved, analysed and results could be presented on geospatial mode for data dissemination for disaster management. Slightly damageable ground motions are expected from the 100 ± 10 years return period earthquakes (~M5.5). Lateritization is a process of low-temperature weathering associated with mineralogical breakdown and the degree of weathering diminishes with depth. Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Northwest striking faults under the Deccan Traps are believed to exist in this region (Chandra, 1977). It is believed that, the bending of the Indian plate is due to the collision of the Indian plate with Tibet plate that generated the elastic stress build-up within the tectonic pockets. Guha, S. K., Gosavi, P. D., Padale, J. G., and Marwadi, S. C., Third Symp Earthquake Engineering Roorkee, 399 (1966). 2007. and JavaScript. High Precision earthquakes in Koyna-Warna seismic zone reveal depth variation in brittle-ductile transition zone, Geophysical Research Letter, 32(8). 2007. (2) by assuming that the rate of earthquake occurrence in time is governed by the Poisson law. 2011. This results in consequent slip along the faults and cause seismic activity in the Peninsular India. The western margin of India has a nearly straight NNW-SSE trending coastline that gradually rises in a step-like pattern and all of a sudden a drastic change in elevation could be observed. 3). Considerable regional fracture lineaments in the study area are N-S (strong geomorphic and geophysical expression), NW-SE (strong geomorphic and geophysical expression), NE-SW (moderate Geomorphic and geophysical expression) and E-W (not clear). Privacy Pure and Applied Geophysics 150: 473–492. However, earthquakes events such as 2001 M7.7 (Bhuj), 1993 M6.3 (Killari), 1997 M5.7 (Jabalpur), and 1967 M6.5 (Koyna), stressed the need for the revisiting of the stable continent belief as manifested by intra-plate earthquakes.