Attenuation studies based on local earthquake Coda waves in the southern Indian peninsular shield |
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| Authors: | C H Patanjali Kumar C S P Sarma M Shekar R K Chadha |
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| Institution: | (1) National Geophysical Research Institute, Hyderabad, 500 007, India |
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| Abstract: | The Dharwar craton, Cuddapah basin and the Godavari graben characterise three diverse geological and tectonic settings in
the peninsular shield of India. Owing to their contiguous proximity, they offer a unique opportunity to document differences,
if any, in their seismic wave attenuation characteristics that might have a bearing on the seismogenic nature of the crust
in a craton, basin and a rift-like graben structure. An attempt is made here to bring out these differences using constraints
from coda-Q. We considered local earthquakes with epicentral distances ranging from␣14 to 150 km recorded at the digital broadband stations
at Dharwar (DHD), Cuddapah (CUD) and Kothagudem (KGD) regions to derive the frequency-dependent coda-Q relations. Using the single scattering method, we obtained the frequency-dependent Q
C relationship (Q
C = Q
0
f
n
)for each of the three geological units separately: DHD: Q
C = (730.62 ± 0.09)f
(0.54 ± 0.01); CUD: Q
C = (535.06 ± 0.13)f
(0.59 ± 0.01) and KGD: Q
C = (150.56 ± 0.08)f (0.91 ± 0.01). The Q
C values obtained for all the three sub-regions show moderate to strong frequency dependence and essentially reflect the level
of crustal heterogeneities to varying degrees. |
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| Keywords: | Attenuation Coda waves Local earthquakes South Indian shield |
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