Anatomy of surface rupture zones of two stable continental region earthquakes, 1967 Koyna and 1993 Latur, India

Gupta, Harsh K.; Rao, R. U. M.; Srinivasan, R.; Rao, Gang; Reddy, G. K.; Dwivedy, K. K.; Banerjee, Debabrata; Mohanty, R.; Satyasaradhi, Y. R.

doi:10.1029/1999gl900399

Cited by 63 publications

(27 citation statements)

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“…The present structural analysis on the variations in attitudes of basalt fl ows on the Lonar crater rim together with the valuable observations of Kumar (2005) on the deformations in the mostly inaccessible upper ~30 m of the crater wall perhaps give a better idea of the impactinduced deformations when an impactor hits obliquely a thick basaltic sequence (>350 m, Gupta et al, 1999;Mitchell and Widdowson, 1991). Both data sets suggest upward turning of basalt fl ows along the crater wall similar to the impact deformation of target rocks at other simple craters (Shoemaker, 1960;Shoemaker and Eggleton 1961;Brandt and Reimold, 1995;Koeberl et al, 1998;Reimold et al, 1998b).…”

Section: Discussionmentioning

confidence: 98%

“…Fudali et al (1980) suggested a thickness of 600-700 m. A thickness of basalt fl ows more than 350 m in the Lonar region (Kumar, 2005) seems to be more reasonable. This is because drilling at the 1993 Latur earthquake site, which is located ~150 km south of the Lonar, suggests a thickness of the basalt sequence of ~350 m in this area that overlies on March 2, 2010 gsabulletin.gsapubs.org Downloaded from the Archean granites and gneisses (Gupta et al, 1999). Because several studies indicate a northward increase of thickness of Deccan basalt (Mitchell and Widdowson, 1991), an estimated thickness of basalt fl ows more than 350 m in the Lonar area is more reasonable.…”

Section: Regional Geologymentioning

confidence: 96%

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Structural and anisotropy of magnetic susceptibility (AMS) evidence for oblique impact on terrestrial basalt flows: Lonar crater, India

Misra

Arif

Basavaiah

et al. 2009

Geological Society of America Bulletin

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The anisotropy of magnetic susceptibility (AMS) technique, combined with the analyses of satellite images and the geological structure, are examined on Lonar crater , a small, ~1.8-km-diameter impact crater in India, to evaluate the direction and obliquity of asteroid impact. The Advanced Spaceborne Thermal Emission and Refl ection Radiometer (ASTER) image (15-m resolution) of the ca. 52 ka Lonar crater in the subhorizontal Deccan basalt (ca. 65 Ma) shows that this simple, bowl-shaped impact crater has a near-circular rim with a circularity of ~0.95. Most of the highly refl ecting, continuous-ejecta blanket around the crater rim can be enveloped with an ellipse whose major E-W axis is coincident with the diameter of the crater rim and minor N-S axis is relatively displaced toward the west by ~200 m. The present ejecta distribution, which appears to be close to its pristine shape, extends to a distance of ~700 m in all the directions from the crater rim except to the west where it extends to a distance of a little more than 1 km. The circular shape of the crater rim, the E-W bilateral symmetry of the enveloping ellipse on the ejecta, and the greater extension of the ejecta toward the west appear to be the result of an oblique impact from the east with an angle of incidence of 30°-45° when compared with experiments. The AMS data suggest that the target basalts occurring at ~2 km west-southwest of the crater rim are highly shocked, as indicated by the random orientation of their K 3 susceptibility axes in comparison to the unshocked basalts at ~2 km east-southeast of the crater; the unshocked basalts show a bimodal distribution of susceptibility axes typical of lava fl ows. Moderate to strong westward shifts of the K 3 axes are seen for the majority of the shocked basalts on the crater rim and westsouthwest of the crater; the shocked basalts also indicate an oblique impact from the east when compared with modeling and experiments. A general lowering of degree of anisotropy of the Lonar shocked basalts (~1.01) compared to the surrounding unshocked basalts (~1.03) is found to be a characteristic feature of impact crater target rocks. Variation in attitudes of the basalt fl ows on the Lonar crater rim shows a bilaterally symmetrical distribution about an E-W axial plane, which includes quaquaversal dips of the fl ows all around the crater rim, except to the west where overturned dips of the basalt fl ows are seen. It appears that oblique impact and the symmetry in structural variations around the crater rim have a relationship for a small crater such as Lonar.

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Section: Discussionmentioning

confidence: 98%

Section: Regional Geologymentioning

confidence: 96%

Structural and anisotropy of magnetic susceptibility (AMS) evidence for oblique impact on terrestrial basalt flows: Lonar crater, India

Misra

Arif

Basavaiah

et al. 2009

Geological Society of America Bulletin

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“…The samples of ferrous saponite were obtained from the secondary fillings of the Killari borehole in the Deccan Flood basalts, which had been drilled after the Latur earthquake on September, 30, 1993(Gupta et al 1999. The chemical composition of the samples was determined by electron probe micro analyser (EPMA) and also by using a Hitachi S-520 scanning electron microscope (SEM) in EDAX mode with a filament current of 110 mA and an accelerating voltage of 20 kV.…”

Section: Data and Analysismentioning

confidence: 99%

Environmental mineralogy: spectroscopic studies on ferrous saponite and the reduction of hexavalent chromium

et al. 2006

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A green-coloured phyllosilicate occurring on the walls of amygdaloidal cavities and along fractures in the Deccan Flood basalts at Killari, Maharashtra, India, has been identified as iron-rich saponite with a chemical composition [Na 0.60 K 0.40 Ca 0.47 ] {Mg 2.05 Fe 3.95 } (Si 6.45 Al 1.55 ) O 20 (OH) 4 . In order to explore the possible application of this phyllosilicate for environmental management, we have carried out X-ray photon spectroscopic (XPS) and diffuse reflectance spectroscopic (DRS) measurements on the dichromate solutions, in both the untreated and treated form. The dichromate solution treated with the saponite samples show a remarkable capability not only to adsorb hexavalent chromium but also effect a reduction of hexavalent to trivalent chromium at an efficiency of 75%. These valence states of chromium were characterised unambiguously by XPS and DRS spectra collected at room temperature. Our studies show that Killari saponite is capable of reducing Cr (VI) to Cr (III). The ferrous saponite in Deccan Flood basalts could therefore be a useful mineral in environmental management in areas affected by Cr(VI) effluents.

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“…1; TALWANI , 1997). Recently, the results of drilling and helium studies for a small region on the NNE Dhonechiwada fault (inferred causative fault for 10 December, 1967 Koyna mainshock) revealed that the seismogenic fault dips at an angle 60 o towards WNW (GUPTA et al, 1999). …”

Section: Reservoir Triggered Seismicitymentioning

confidence: 99%

Self-organized Fractal Seismicity of Reservoir Triggered Earthquakes in the Koyna-Warna Seismic Zone, Western India

Mandal

Mabawonku

Dimri

2005

Pure appl. geophys.

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Analysis of the Koyna-Warna earthquake catalog shows that on an average there is a positive correlation between the b value (decrease) and fractal dimensions (decrease in both D 2 s and D 2 t ) of earthquake epicenters 0.5 and 2.5 years prior to 1973 (M5.2) and 1980 (M5.5) events, respectively, except a negative correlation for about five years (1988)(1989)(1990)(1991)(1992)(1993) prior to the 1993/1994 sequence (M5.4). This positive correlation indicates a weaker clustering, or that the epicenters tend to fill the twodimensional plane. While the origin of the negative correlation seems to be that during periods of large events (low b value), there is strong clustering around the main shock epicenter (high fractal dimension). Interestingly, during the last year (1995)(1996) of the studied period both the b value and correlation dimensions rose significantly, suggesting that stress release occurs through increased levels of low magnitude and increasingly scattered seismicity, suggesting an increased risk of larger magnitude events. Incidentally, during 2000 three earthquakes of magnitude M ‡ 5.0, one earthquake of M 4.0, 45 earthquakes of magnitude M 3.0-3.9, and several thousand earthquakes of M < 3 have occurred in the region. Thus it can be inferred that at local scales the relationship yields both positive and negative correlation that appears to be controlled by different modes of failure within the active fault complex.

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Anatomy of surface rupture zones of two stable continental region earthquakes, 1967 Koyna and 1993 Latur, India

Cited by 63 publications

References 10 publications

Structural and anisotropy of magnetic susceptibility (AMS) evidence for oblique impact on terrestrial basalt flows: Lonar crater, India

Structural and anisotropy of magnetic susceptibility (AMS) evidence for oblique impact on terrestrial basalt flows: Lonar crater, India

Environmental mineralogy: spectroscopic studies on ferrous saponite and the reduction of hexavalent chromium

Self-organized Fractal Seismicity of Reservoir Triggered Earthquakes in the Koyna-Warna Seismic Zone, Western India

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