Koyna Earthquake

Narain, Hari; Gupta, Harsh K.

doi:10.1038/2171138a0

Cited by 62 publications

(13 citation statements)

References 1 publication

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“…At Koyna in India (Narain & Gupta 1968) the river was dammed in 1962 and tremors were reported soon afterwards. Between September 1964 and March 1966 some sixty-one tremors were recorded, at depths of order 4km.…”

Section: Other Cases Of Induced Seismic Activitymentioning

confidence: 99%

Load-induced Earthquakes at Lake Kariba?II

Gough¹,

Gough²

1970

Geophys J Int

139

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The filling of the world's largest artificial lake at Kariba has been accompanied and followed by considerable earthquake activity. A local network of three seismographs allowed location of epicentres for 159 of 2000 tremors recorded during three years while the lake filled. The epicentres lie in the down-faulted rift valley of the middle Zambezi and it is clear that the lake has re-activated some of the existing faults, formed in a complex tectonic history since late Precambrian times. Records from permanent observatories have been used in estimates of tremor frequency and rate of energy release through 9.4 years. Calculations of stress distributions at nine lake levels have been used in estimates of the volume V, within which the maximum shear stress exceeds 1 bar, and V, as function of time is compared with the seismic activity. The latter was highly correlated with rise of V, as the lake filled and for three years after.Of total energy 2.32 x lOZ0erg some 88.4 per cent was radiated from seven events of 5.0 < m < 5-8. The main activity built up from June to September 1963, culminating in the last week of September, five weeks after the lake reached its maximum level; during that week five of the seven large shocks and many hundreds of aftershocks occurred. Activity has continued to the present, correlated with water level and more strikingly with V, until mid-1966 but not thereafter, and showing a gradual though far from continuous decline. Magnitude-frequency *

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Section: Other Cases Of Induced Seismic Activitymentioning

confidence: 99%

Load-induced Earthquakes at Lake Kariba?II

Gough¹,

Gough²

1970

Geophys J Int

139

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“…Since the impoundment of Koyna reservoir in 1962 and the nearby Warna reservoir in 1985, triggered earthquakes are occurring in the vicinity of these two reservoirs (Narain and Gupta, 1968;Gupta, 1992;Gupta, 2002). The earthquakes occur in an area of about 20x30 km 2 in the Koyna-Warna region (henceforth referred to as the Koyna region).…”

Section: Introductionmentioning

confidence: 99%

Short Term Earthquake Forecasts at Koyna, India

Gupta

Shashidhar

Rao

et al. 2011

Journal of the Geological Society of India

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Earthquake activity is monitored in real time at the Koyna reservoir in western India, beginning from August 2005 and successful short term forecasts have been made of M ~ 4 earthquakes. The basis of these forecasts is the observation of nucleation that precedes such earthquakes. Here we report that a total of 29 earthquakes in the magnitude range of 3.5 to 5.1 occurred in the region during the period of August 2005 through May 2010. These earthquakes could broadly be put in three zones. Zone-A has been most active accounting for 18 earthquakes, while 5 earthquakes in Zone-B and 6 in Zone-C have occurred. Earthquakes in Zone-A are preceded by well defined nucleation, while it is not the case with zones B and C. This indicates the complexity of the earthquakes processes and the fact that even in a small seismically active area of only 20 km x 30 km earthquake forecast is difficult.

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“…It is also unusual in that it almost certainly seems to be intimately related to the impoundment of the nearby reservoir. Numerous authors [Narain and Gupta, 1968;Guha et al, 1970;Aki, 1972] have described the details and significance of the events leading up to and including the main shock of the Koyna earthquake series, so these will not be discussed here.…”

Section: The Koyna Earthquakementioning

confidence: 99%

A body wave inversion of the Koyna, India, earthquake of December 10, 1967, and some implications for body wave focal mechanisms

Langston¹

1976

J. Geophys. Res.

114

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With a generalized inverse technique, WWSSN (World-Wide Standard Seismograph Network) longperiod P and SH wave forms are analyzed from the Koyna earthquake. The effects of local plane-layered earth structure near an imbedded point dislocation source are put in by using a modified plane-wave ray theory which includes the standard reflection and transmission coefficients plus source corrections for radiation pattern and geometrical spreading. The generalized inverse compares synthetic seismograms to the observed ones in the time dom!lin through the use of a correlation function. By using published crustal models of the Koyna region and primarily by modelling the crustal phases P, pP, and sP, the first 25 s of the Jong-period wave forms is synthesized for 17 stations, and a focal mechanism is obtained for the. Koyna earthquake which is significantly different from previous mechanisms. The fault orientation is 67° dip to the east, -29° rake plunging to the northeast, and Nl6°E strike, all angles being ±6°. This is an eastward dipping, left lateral oblique slip fault which agrees favorably with the trend of fissures in the meizoseismal area. the source time duration is estimated to be 6.5 ± 1.5 s from a triangular time pulse which has a rise time of 2.5 s, a tail-off of 3.9 s, source depth of 4.5 ± 1.5 km, and seismic moment of 3.2 ± 1.4 x 102• dyn cm. Some short-period complexity in the time function is indicated by modelling shortperiod WWSSN records but 1s complicated by crustal phases. The long-period P wave forms exhibit complicated behavior due to intense crustal phase interference caused by the shallow source depth and radiation pattern effects. These structure effects can explain much of the apparent multiplicity of the Koyna source. An interpretation of the Koyna dam accelerograms has yielded an S-P time which can be used along with the IM D (Indian Meteorological Department) epicenter and present depth determination to place the epicenter directly on the meizoseismal area.

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Koyna Earthquake

Cited by 62 publications

References 1 publication

Load-induced Earthquakes at Lake Kariba?II

Load-induced Earthquakes at Lake Kariba?II

Short Term Earthquake Forecasts at Koyna, India

A body wave inversion of the Koyna, India, earthquake of December 10, 1967, and some implications for body wave focal mechanisms

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