Page 33 - Jabalpur_EQ

Chapter 2 Seismologlcal Aspects

this zone has been assigned a magnitude value of 6.0 which falls in the above
range. Therefore, it can be concluded that the maximum upper limit of magni-
tude in the Narmada seismic zone seems to be around 6.5.

In the absence of local networks of seismographs in this region most of the micro-
earthquake activity has neither been recorded nor reported. The mapping of the
micro-earthquake activity provides the significant information on local seismic
ity of the region and activity of the existing faults. Several possible reasons have
been assigned by various investigators to explain the observed pattern of seis-
micity of the Peninsular India. It is generally advocated that the fault pattern have
significant influence and perhaps governs the occurrence of earthquakes in the
Peninsular India.

Rao and Murty (1970) and Naqvi et al. (1974) have delineated six continental
nuclei, around which three protocontinents, namely, Dhanwar, Aravalli and
Singhbhum, have developed in the Indian shield and the seismicity of varying
degree is observed in each of protocontinents. The margins of the Dhanwar pro-
tocontinent are moderately active, and the seismicity in the Aravali protoconti-
nent appears to be low except at places like Kutch and Bhuj. In the Singhbhum
protocontinent, the seismicity is very low except for some significant earthquakes
like Calcutta (October 11, 1737) and Bhadrachalam (April 13, 1969). Thus, based

26

M4
Umerkot
25 (1921) 5>M>4
Sagar 6>M>5
(1987) (1985)
M>6

24
(1993)
(1997)
Jabalpur Netaghat
(1973) (1962)
. JABALPUR
23
Son Valleey
Mandia, 1903) (1927)
(1985)
22 Balaghat
Betu (1957) Thethaghat
(1968) ('963)
Nagpu
(1957)
21
78 79 80 81 82 83 84 85
Longitude (E)

Figure 2-5. Seismicity of the Jabalpur area.

Jabalpur Earthquake of May 22. 1997 23