Barkhan (Balochistan) earthquakes of June 26 and July 12, 1999: Source parameters from teleseismic body waves
Keywords:
Barkhan; Earthquake; Sulaiman ranges; Source parameters; Teleseismic body waves; Focal mechanism solutions; Seismic momentAbstract
Two moderate earthquakes occurred on June 26 and July 12, 1999 at Barkhan, in at the northern limb of the Sibbi Syntaxis occupied by the southern Sulaiman Ranges. Source characteristics of these earthquakes were studied using the teleseismic body waves recorded at the IRIS Global Seismographic Network. The P and SH waveforms of these events were inverted to double couple source using the method of Kikuchi and Kanamori (1991). The azimuthal coverage of seismograph stations is good enough to resolve some details of heterogeneous moment tensor. Orientation and length of the fault are derived from aftershocks related with this earthquake event. The data show that the slip on the northeastern sections of the Karmari and Barkhan thrusts was responsible for these earthquakes. The focal mechanism solutions suggest thrust faulting. The strike, dip and rake of the causative fault of the June 26 earthquake are respectively 243o, 39o and 92o and that of July 12, earthquake is 237o, of 32o, and 111o. The seismic moment is estimated as Mo = 2.3 x 1017 Nm for June 26 and Mo = 3.3 x1017 Nm for July 12, 1999.
References
Abdul-Gawad, M., 1971. Wrench movement in the Balochistan and relation to HimalayanIndian Ocean Tectonics. Bulletin Geological Society of America, 82, 1235-1250.
Aki, K., 1966. Generation and propagation of G waves from the Niigata earthquake at June 16, 1964. Bulletin Earthquake Research Institute, Tokyo University, 44, 73-88.
Bannert D., Cheema A., Ahmed, A., Schaffer, U., 1992. The Geology of the Western Fold Belt: Structural Interpretation of LANDSAT-MSS Satellite Imagery, Pakistan (1:500,000). Federal Institute of Geosciences and Natural Resources (BGR), Hannover, Germany.
Bender, F.K., Raza H. A., 1995. Geology of Pakistan. Gebruder Borntraeger, BerlinStuttgart, Germany.
Fukao, Y., Kikuchi, M., 1987. Source retrieval for mantle earthquakes by iterative deconvolution of long period P-waves. Tectonophysics, 144, 249-269.
Futterman, W.I., 1962. Dispersive body wave. Journal of Geophysical Research, 67, 5279-5291.
Helmberger, D.V., 1983. Theory and application of synthetic seismograms, in Earthquakes: Observation, Theory and Interpretation. Societa Italiana di Fisica, Bologna, Italy, 174-222.
Jeffreys, H., Bullen K.H., 1940. Seismological Tables, British Association for the Advancement of Science, London.
Kikuchi, M., Kanamori, H., 1986. Inversion of complex body waves-II. Physics of the Earth and Planetary Interiors, 43, 205-222.
Kikuchi, M., Kanamori, H., 1991. Inversion of complex body waves-III. Bulletin Seismological Society of America, 79, 670-689.
Lawrence, R. D., Khan, S. H., DeJong, K. A., Farah, A., Yeats, R.S., 1981. Thrust and strike-slip fault interaction along the Chaman fault zone, Pakistan. In: McClay, K. R., Price, N. J. (Eds.), Thrust and Nappe Tectonics. Geological Society of London, Special Publication, 9, 363-370.
Lee, W.H.K., 1990. HYPO71PC Programme, IASPEI Software Library, 1.
Sarwar, G., DeJong, K. A., 1979. Arcs, oroclines, syntaxes: The curvature of mountain belts in Pakistan. In: Farah, A., DeJong, K.A. (Eds.), Geodynamics of Pakistan. Geological Survey of Pakistan, 351-358.
