Figure 15. Regional network of 11 broadband seismological
stations in NE India operated by Indian Institute of Geomagnetism. (Courtesy IIG)
A regional network of 11 broadband seismological stations has been
established and operated by IIG in NE India (Fig.15) to study the
geometry and continuity of crust and upper mantle discontinuities
beneath the region, seismic ambient noise tomography focusing primarily
on crustal and uppermost mantle structures, and crustal attenuation
characteristics of high frequency body waves.
Strong motion accelerographs
(SMA) have been installed and operated by CSIR-NEIST at different places
in and around the Shillong Plateau and Mikir Hills. The acceleration
time histories obtained from these accelerographs are filtered and
processed for baseline corrections on a regular basis. These are then
used as inputs for the estimation of several ground motion parameters
including PGA, PGV and PGD, and Response spectra. A total of 234
earthquake events (M \(\ge\) 3.5) have been recorded by these SMA stations
during Sep.2016 to Sep.2021.
The Gujarat State Seismic Network (GSNet) under the aegis of the ISR,
Gandhinagar, is operational since July 2006 (Fig.16). Presently, the
network consists of 54 broadband seismograph stations (BBS) spread out
in the state and neighboring areas. The data from almost 45 BBS are
transmitted to the Institute through VSAT, where the earthquake activity
is monitored in near real time (24x7).The network has a detectability of
M 1.5 in the Kachchh region and M 2.0 in the other areas of Gujarat.
Based on earthquake data of the Gujarat region, ISR developed a
calibrated local magnitude scale (ML) for Kachchh and
Saurashtra regions. ISR has also procured 10 compact broadband sensors
with 4G connectivity. In addition, 54 strong motion accelerographs are
also deployed by ISR. It has also established three MPGOs in Kachchh for
earthquake precursory studies.