Active intraplate deformation in south India

Subrahmanya, K. R.

doi:10.1016/0040-1951(96)00005-4

Cited by 68 publications

(31 citation statements)

References 6 publications

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“…Evidence for two such upwarps began to accumulate in the 1980s and 1990s, the first of them running east from Cochin (I on figure 5) [52] and the second between Mangalore and Madras (II). Along the latter there was evidence for a thin crust and anomalously positive values for gravity, both of them consistent with extension and the presence of mantle rocks relatively close to the surface, microseismicity associated with pervasive rock fracturing, and above all the displacement of river channels away from the proposed axis of uplift [34].…”

Section: Phil Trans R Soc a (2012)mentioning

confidence: 84%

River history and tectonics

Vita‐Finzi

2012

Phil. Trans. R. Soc. A.

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The analysis of crustal deformation by tectonic processes has gained much from the clues offered by drainage geometry and river behaviour, while the interpretation of channel patterns and sequences benefits from information on Earth movements before or during their development. The interplay between the two strands operates at many scales: themes which have already benefited from it include the possible role of mantle plumes in the breakup of Gondwana, the Cenozoic development of drainage systems in Africa and Australia, Himalayan uplift in response to erosion, alternating episodes of uplift and subsidence in the Mississippi delta, buckling of the Indian lithospheric plate, and changes in stream pattern and sinuosity along individual alluvial channels subject to localized deformation. Developments in remote sensing, isotopic dating and numerical modelling are starting to yield quantitative analyses of such effects, to the benefit of geodymamics as well as fluvial hydrology.

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Section: Phil Trans R Soc a (2012)mentioning

confidence: 84%

River history and tectonics

Vita‐Finzi

2012

Phil. Trans. R. Soc. A.

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“…As per IS 1893 (BIS 2002), seismic study area falls in the upgraded zones II and III in the seismic zonation map of India. Srinivasan and Sreenivas (1977), Valdiya (1998), Purnachandra Rao (1999), Ramalingeswara Rao (2000), Subrahmanya (1996Subrahmanya ( , 2002, Ganesha Raj (2001), Sridevi Jade (2004), Ganesha Raj and Nijagunappa (2004), Sitharam et al (2006) and Sitharam and Anbazhagan (2007) highlight that seismic activity in the peninsular India has increased when compared to the past. Reddy (2003) highlighted that the south Indian seismicity is neither understood properly nor given importance since it is of micro-dimensions.…”

Section: Seismicity Of the Regionmentioning

confidence: 95%

Probabilistic seismic hazard analysis for Bangalore

2008

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This article presents the results of probabilistic seismic hazard analysis (PSHA) for Bangalore, South India. Analyses have been carried out considering the seismotectonic parameters of the region covering a radius of 350 km keeping Bangalore as the center. Seismic hazard parameter 'b' has been evaluated considering the available earthquake data using (1) Gutenberg-Richter (G-R) relationship and (2) Sellevoll (1989, 1992) method utilizing extreme and complete catalogs. The 'b' parameter was estimated to be 0.62 to 0.98 from G-R relation and 0.87 ± 0.03 from Kijko and Sellevoll method. The results obtained are a little higher than the 'b' values published earlier for southern India. Further, probabilistic seismic hazard analysis for Bangalore region has been carried out considering six seismogenic sources. From the analysis, mean annual rate of exceedance and cumulative probability hazard curve for peak ground acceleration (PGA) and spectral acceleration (Sa) have been generated. The quantified hazard values in terms of the rock level peak ground acceleration (PGA) are mapped for 10% probability of exceedance in 50 years on a grid size of 0.5 km 9 0.5 km. In addition, Uniform Hazard Response Spectrum (UHRS) at rock level is also developed for the 5% damping corresponding to 10% probability of exceedance in 50 years. The peak ground acceleration (PGA) value of 0.121 g obtained from the present investigation is slightly lower (but comparable) than the PGA values obtained from the deterministic seismic hazard analysis (DSHA) for the same area. However, the PGA value obtained in the current investigation is higher than PGA values reported in the global seismic hazard assessment program (GSHAP) maps of Bhatia et al. (1999) for the shield area.

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“…Ramalingeswara Rao (2000) carried out strain rate and heat flow study in the southern India and characterized as medium to low seismicity region. Subrahmanya (2002 and1996) highlights that the entire study area becoming seismically active due to the upwarping of Mulki-Pulicat Lake (MPL) axis which connects 13 • N in west to 13.4 • N in east. He concludes that there is lot seismic activity around this Mulki-Pulicat Lake axis and in particular he highlights that micro to meso-seimicity to the south and mega seismicity to the north of the MLP axis.…”

Section: Study Area and Seismicitymentioning

confidence: 99%

Use of remote sensing and seismotectonic parameters for seismic hazard analysis of Bangalore

Sitharam

Anbazhagan

Raj

2006

Nat. Hazards Earth Syst. Sci.

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Abstract. Deterministic Seismic Hazard Analysis (DSHA) for the Bangalore, India has been carried out by considering the past earthquakes, assumed subsurface fault rupture lengths and point source synthetic ground motion model. The sources have been identified using satellite remote sensing images and seismotectonic atlas map of India and relevant field studies. Maximum Credible Earthquake (MCE) has been determined by considering the regional seismotectonic activity in about 350 km radius around Bangalore. The seismotectonic map has been prepared by considering the faults, lineaments, shear zones in the area and past moderate earthquakes of more than 470 events having the moment magnitude of 3.5 and above. In addition, 1300 number of earthquake tremors having moment magnitude of less than 3.5 has been considered for the study. Shortest distance from the Bangalore to the different sources is measured and then Peak Horizontal Acceleration (PHA) is calculated for the different sources and moment magnitude of events using regional attenuation relation for peninsular India. Based on Wells and Coppersmith (1994) relationship, subsurface fault rupture length of about 3.8% of total length of the fault shown to be matching with past earthquake events in the area. To simulate synthetic ground motions, Boore (1983Boore ( , 2003 SMSIM programs have been used and the PHA for the different locations is evaluated. From the above approaches, the PHA of 0.15 g was established. This value was obtained for a maximum credible earthquake having a moment magnitude of 5.1 for a source Mandya-Channapatna-Bangalore lineament. This particular source has been identified as a vulnerable source for Bangalore. From this study, it is very clear that Bangalore area can be described as seismically moderately active region. It is also recommended that southern part of Karnataka in particular Bangalore, Mandya and Kolar, need to be upgraded from current Indian Seismic Zone II Correspondence to: T. G. Sitharam (sitharam@civil.iisc.ernet.in) to Seismic Zone III. Acceleration time history (ground motion) has been generated using synthetic earthquake model by considering the revised regional seismotectonic parameters. The rock level PHA map for Bangalore has been prepared and these maps are useful for the purpose of seismic microzonation, ground response analysis and design of important structures.

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Active intraplate deformation in south India

Cited by 68 publications

References 6 publications

River history and tectonics

River history and tectonics

Probabilistic seismic hazard analysis for Bangalore

Use of remote sensing and seismotectonic parameters for seismic hazard analysis of Bangalore

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