University of Roorkee

Chamoli Earthquake of March 29, 1999

Strong Motion Data Recorded at
Department of Earthquake Engineering
University of Roorkee, Roorkee

The Garhwal region of Western Himalayas was rocked by a moderate earthquake (magnitude 6.8 M_L ) on March 29, 1999 at 00:36 hours I.S.T. The epicenter of this earthquake was located near Nandprayag in Chamoli district. Severe damage to constructed facilties has been reported in the epicentral tract as well as in places as far as New Delhi. The tremors were felt in locations as far as Pune in Maharashtra (about 1500 kms from the epicenter). The strong motion accelerographs installed at the Department of Earthquake Engineering (DEQ) have recorded these motions. The total duration of the records obtained at DEQ is 43.52 seconds. Following is the summary of characteristics of strong motion recorded at DEQ.The corrected time histories of the ground acceleration recorded at DEQ are shown in Fig. 1.

Strong Motion Parameters

Peak Ground Acceleration
0.056 g (Long./N 55 W)
0.047 g (Trans./N 35 E)
0.017 g (Vert.)
Strong Motion Duration
(90% duration)
27.24 s (Long./N 55 W)
28.62 s (Trans./N 35 E)
30.22 s (Vert.)
Characteristic Frequency
2.42 Hz (Long./N 55 W)
2.56 Hz (Trans./N 35 E)
5.23 Hz (Vert.)

The 5% damping acceleration response sepctra for these motions is shown in Fig. 2. Further, the Fourier amplitude spectra for each of these records are shown in Fig. 3.

Figure 1: Acceleration time histories recorded at DEQ

Figure 2 : 5% damping acceleration response spectrum for motion recorded at DEQ

Figure 3: Fourier amplitude spectra of acceleration time histories recorded at DEQ