Image: Arunachal Pradesh (Wikimedia commons)
The Tuting-Tidding Suture Zone (TTSZ) is a major part of the Eastern Himalaya, where the Himalaya takes a sharp southward bend and connects with the Indo-Burma Range.
Basic Facts
This part of the Arunachal Himalaya has gained significant importance in recent times due to the growing need of constructing roads and hydropower projects, making the need for understanding the pattern of seismicity in this region critical.
A study by the Wadia Institute of Himalayan Geology (WIHG) an autonomous institute of the Department of Science & Technology (DST) exploring the elastic properties of rocks and seismicity in this easternmost part of India revealed that the area is generating moderate earthquakes at two different depths.
Low magnitude earthquakes are concentrated at 1-15 km depth, and slightly higher greater than 4.0 magnitude earthquakes are mostly generated from 25-35 km depth. The intermediate-depth is devoid of seismicity and coincides with the zone of fluid/partial melts.
The crustal thickness in this area varies from 46.7 km beneath the Brahmaputra Valley to about 55 km in the higher elevations of Arunachal, with a marginal uplift of the contact that defines the boundary between crust and the mantle technically called the Moho discontinuity.
This, in turn, reveals the underthrusting mechanism of Indian plate in the Tuting-Tidding Suture Zone. Extremely high Poisson’s ratio was also obtained in the higher parts of the Lohit Valley, indicating the presence of fluid or partial melt at crustal depths. This detailed assessment of seismicity in this region will be helpful for planning any largescale construction in this region in the future.
(Source: PIB)
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