Session Start Date

6-1-1988

Abstract

Tarbela Dam which is by volume (105 million m3) the world's largest earth and rock filled dams is located on the middle Indus River in northern Pakistan. Having a length at crest of 2.7 Km and maximum height 143 m, its reservoir has an area of about 100 Sq. Kms, with a maximum depth of about 130 m and gross capacity of 13.7 Km3. Complete first impounding of reservoir was carried out during 1975 and since then it has completed twelve filling-release cycles. To study the induced seismic behaviour of Tarbela Reservoir data analysis regarding number of seismic events and energy release has been carried out, taking an area of 50 Km radius around Tarbela Dam. Local Scale was used for magnitude calculations and the energy releases were computed through Richter's formula: Log E= 9.9 + 1.9M- 0.024M3. It was established that the rate of energy release is six times greater when the reservoir is below 120 m height than above 120 m. The energy release during June to October on the average is lower, while from November to May on the average it is higher when compared with pre-impounding seismicity level. Also it was concluded that for the two prominent faults i.e. Indus-Darband and Tarnawi-Punjal, the rate of energy release is three times greater when reservoir level is below 120 m than above 120 m.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

Publication Date

6-1-1988

Document Version

Final Version

Rights

© 1988 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Jun 1st, 12:00 AM

Tarbela Reservoir A Question of Induced Seismicity

Tarbela Dam which is by volume (105 million m3) the world's largest earth and rock filled dams is located on the middle Indus River in northern Pakistan. Having a length at crest of 2.7 Km and maximum height 143 m, its reservoir has an area of about 100 Sq. Kms, with a maximum depth of about 130 m and gross capacity of 13.7 Km3. Complete first impounding of reservoir was carried out during 1975 and since then it has completed twelve filling-release cycles. To study the induced seismic behaviour of Tarbela Reservoir data analysis regarding number of seismic events and energy release has been carried out, taking an area of 50 Km radius around Tarbela Dam. Local Scale was used for magnitude calculations and the energy releases were computed through Richter's formula: Log E= 9.9 + 1.9M- 0.024M3. It was established that the rate of energy release is six times greater when the reservoir is below 120 m height than above 120 m. The energy release during June to October on the average is lower, while from November to May on the average it is higher when compared with pre-impounding seismicity level. Also it was concluded that for the two prominent faults i.e. Indus-Darband and Tarnawi-Punjal, the rate of energy release is three times greater when reservoir level is below 120 m than above 120 m.