HR: 16:30h
AN: T34A-01    [Abstracts]
TI: Spatial Radon and Helium Anomalies along Major Thrust/Faults of Himachal Himalayas, India
AU: * Mahajan, S
EM: mahajansandeep21@gmail.com
AF: Department of Physics, Guru Nanak Dev Univerisity, Amritsar, Pb 143005, India
AU: Bajwa, B S
EM:
AF: Department of Physics, Guru Nanak Dev Univerisity, Amritsar, Pb 143005, India
AU: Kumar, A
EM:
AF: Department of Physics, Guru Nanak Dev Univerisity, Amritsar, Pb 143005, India
AU: Walia, V
EM:
AF: National Centre for Research on earthquake Engineering, Taipei, Taiwan, Taipei, 106, Taiwan
AU: Singh, S
EM:
AF: Department of Physics, Guru Nanak Dev Univerisity, Amritsar, Pb 143005, India
AU: Yang, T F
EM:
AF: Department of Geosciences, National Taiwan University, Taipei, 106, Taiwan
AB: The Himalayan mountains are highly unstable and seismically very active. The seismicity in the Himalayan belt is closely associated with the active faults and folds trending normal or oblique to the main Himalayan trend, which leads to under thrusting of the blocks. The state of Himachal Pradesh is considered to be seismically very active because as per the Seismic Zonation Map of India, most of its area falls in two seismic zones, i.e. Very High Damage Risk Zone, zone V, and High Damage Risk Zone, zone IV. The Himachal Himalayas are broadly divided into two major tectonic zones viz. the Lesser Himalayan tectogen in the south and Tethyan Himalayan tectogen in the north. The lesser Himalayan tectogen lies mainly on the southern part of Himachal Pradesh state and is bounded between Main Central Thrust (MCT) and Main Boundary Thrust (MBT). The MCT and MBT are associated with evolution of Himalayan orogeny. Besides the longitudinal lineaments several transverse lineaments occur as faults and fractures trending normally or obliquely to Himalayan trend. In an effort to signify the role of radon and helium as a productive tool to delineate some active faults and lineaments, measurements were made in the soil-gas along some of the major thrust (MBT, MCT) areas of Himachal Himalayas. Remote sensing data provides the synoptic coverage of any desired area and has been successfully used to recognize structures having tectonic significance. As a step in identification of active faulting and structural investigation, we will discuss the specific geochemical studies applied with aim of further identifying active faults and also complementing and specifying remotely sensed structures and zones. This method to investigate active tectonic structures, using soil gas composition at faults, provides relevant information about regional stress conditions, which can be obtained rapidly and at relatively low cost. Elevated emanation of radon and helium gases were detected over some of the thrust/faults/lineaments, thus indicating anomalous permeability of these zones in comparison with the adjacent areas. The collected soil gas samples were analyzed for radon and helium using RTM-2100 (SARAD) and Helium leak detector (ALCATEL) respectively. It can be concluded from present study that soil gas radon and helium patterns, combined with morphological and geological observations, can supply useful constraints for deformation tectonic environments. These findings may have important connotations for the long-term seismic hazard assessment of the tectonically active regions of the NW Himalaya. This methodology is an inexpensive method of locating unknown faults. Consequently, our work is a preliminary study in this region and the obtained results will considerably help in constructing the radon and helium map of the faults system in the NW Himalayas, India.
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8010 Fractures and faults
DE: 9320 Asia
SC: Tectonophysics [T]
MN: 2009 Joint Assembly