International Research Journal of Management Sociology & Humanities ISSN 2277 – 9809 (online) ISSN 2348 - 9359 (Print) An Internationally Indexed Peer Reviewed & Refereed Journal Shri Param Hans Education & Research Foundation Trust www.IRJMSH.com www.SPHERT.org Published by iSaRa Solutions IRJMSH Vol 8 Issue 12[Year 2017] ISSN 2277 – 9809 (0nline) 2348–9359 (Print) Rudraprag As a very Sensitive Zone in Terms of Disaster Pramod Kumar Anthwal Abstract: This report assimilates detailed geological account of Rudraprayag district where rocks of both Lesser Himalaya and Central Crystalline are observed to be exposed. Besides some local faults, major dislocations of the area viz., Vaikrita Thrust and Main Central Thrust (MCT) have been mapped. Geologists, particularly those interested in structural set up of the area would appreciate this effort. Key-Word: MCT, Thrust Faults, Seismic Zone, Topography. Introduction: Rudraprayag district falls in Zone V of the Seismic Zoning Map of India (IS 1893, 2002) and earthquakes of 1803 and 1842 reportedly devastated the region. Heavy losses were inflicted to residential and other structures in the areas around Jakholi, Okhimath and Rudraprayag by 1999 Chamoli Earthquake. The course of Mandakini river was reportedly blocked for three days due to landslides in 1857 and then again in 1976. Flash floods in Kunjya Gad, a tributary of Mandakini, inflicted heavy losses in Kontha, Chandranagar and Ajaypur in 1979. The area represents highly rugged and immature topography characterized by moderate to steep slopes that are intervened by narrow valleys. The topography of the region appears to be controlled by the structural and lithological factors. High ridges and summit surfaces of the area remain snow covered from November to March. Major ridges of the area include Bisuri Dhar (4,008 m), Khiri Dhar (3,768 m), Ragsi Dhar (2,818 m) while Sumeru Parvat (6,350 m), Bhart Khunta (6,578 m), Kedarnath (6,940 m), Mahalaya (5,970 m) and Hanuman Top (5,320 m) are some of the well-known peaks. The area thus exhibits high relative relief. Presence of overburden on steep slopes and high precipitation make this area prone to landslides. The "U", "V" and "S" shaped meanders are generally observed all along the valley. On the upstream side valley is narrow and deep, while to the downstream side it becomes wide and sinuous; i.e. around Chandrapuri, Agastmuni and Tilwara. This is attributed to the nature of the bed rocks and bank material. The Study Area: The study area is located at 30° 14’ 29.98” N latitude, 78° 53’ 55.90 E longitude in the middle of Pauri and Rudraprayag district and belongs to lesser Himalaya of Garhwal Region. It lies on the left bank of Alaknanda River and about 15 km upstream of Srinagar to Rudraprayag road NH-58.The study area falls in Survery of India Toposheet No. 53 J/15. The most important historical and religious place i.e. Dhari Devi, located just nearby this slide. The landslide mainly consists of metamorphic rocks, which has been highly weathered due to the tectonic activity of that area (Negi et al, 2013). Geological setting: Two rock sequences are observed to be exposed in Rudraprayag district; sandwiched between North Almora Thrust (NAT) and Main Central Thrust (MCT) constitutes the Lesser Himalaya, while that exposed to the north of MCT constitutes the Higher Himalaya. Geological investigations in the Mandakini valley have been carried out by Dungarkoti and others (1976), Bist and Sinha (1980), Valdiya (1980), Naithani (2002), and Kumar (2005). The Higher Himalayan Central Crystalline rocks are observed to comprise of low, medium and high grade rocks that have been intruded by both acidic and basic rocks. On the basis of lithology and tectonic setup, these rocks are divided into different litho-units. The main rock types observed in the area include granitic gneiss, augen gneiss, garnet mica schist, calc zone and amphibolites. At Bheembali in Mandakini valley and at Gaundar in Madhyameheshwar valley predominance of garnetiferous gneisses of Central Crystallines is observed. Gneisses with calc zone are observed along the Main Central Thrust (MCT) zone; mostly in the area around Kund Chatti, Parakandi, Ransi and between Bareth and Silgad in Sauri Gad catchment (Fig. 10). Downstream of Barasu near Kaladungi Nala quartzite with calc zone is International Research Journal of Management Sociology & Humanity ( IRJMSH ) Page 308 www.irjmsh.com IRJMSH Vol 8 Issue 12[Year 2017] ISSN 2277 – 9809 (0nline) 2348–9359 (Print) observed locally. The area is observed to be traversed by major lithotectonic groups delineated by Main Central Thrust (MCT) and Vaikrita Thrust. Besides these Banswara Thrust is observed to be a major tectonic discontinuity of the area. Rocks of Central Crystallines are observed to be thrust over the rocks of Garhwal Group along MCT. This tectonic boundary is prominently observed across the Mandakini river in close proximity of Kundchatti near Okhimath where it has almost east west trend. In the study area high grade Central Crystalline rocks are observed to be thrust over low to medium grade Central Crystalline rocks along Vaikrita Thrust of Valdiya (1980) that is observed to the north of Gaurikund. The areas in the proximity of tectonic boundaries are observed to be covered with large fans and cones of landslide debris. Apart from large landslides, subsidence zones are also observed around tectonic discontinuities. Lithotectonic succession of the area is given in Table 1. Group Formatiom Member/Rock type Vaikrita Gaurikund Garnetiferous gneiss, schist, quartzite and migmatite Higher Himalaya Vaikrita Thrust (VT) Jutogh Kalimath Porphyritic gneiss and mica schist Okimath Gneiss, garnetiferous schist and calc zone Main Central Thrust(MCT) (Pre-Cambrian to Patroli Granite Sillurian) Garhwal Patroli Quartzite Gwana Garh Dobri dolomite, Dobri Lesser phyllite, Bhishna (Lameri Himalaya B), Massive dolomite (Lameri A) quartzite, Dhanpur dolomite Lameri Massive dolomite (Lameri C), Phyllite/slate Rudraprayag Orthoquartzite-volcanic association with metabasics, phyllite and slate member North Almora Thrust (NAT) Dudhatoli (Pre-Cambrian) Maithana quartzite Pauri Khirsu quartzite Pauri phyllite phyllite, Bhainswara quartzite North Almora Thrust (NAT) separates the Pauri phyllite and Khirsu quartzite of Dudhatoli Group from the Garhwal Group. This contact is observed near Koteshwar, 5 km upstream to Srinagar town. The Garhwal Group rocks of Lesser Himalaya are observed to comprise of low grade metasediments that are intruded by acidic and basic igneous rocks. These consist of thick succession of low grade metasediments made up of quartzite along with penecontemporaneous metabasics and carbonate rocks. The main rock types observed in the area include schistose quartzite, limestone, quartzite, slate, phyllite, granite and metabasics. Granites exposed in the area are observed to be tourmaline and at places chlorite rich and these intrude Rautgara Formation of Garhwal Group to the west of Tilwara. The volcanics are largely observed to be very course grained, non - foliated and generally porphyrytic. The Rautgara Formation is observed to be a sequence of massive cream coloured, purplish and brownish fine grained quartzites that are exposed along Koteshwer - Rudraprayag section in the Alaknanda valley. Garhwal International Research Journal of Management Sociology & Humanity ( IRJMSH ) Page 309 www.irjmsh.com IRJMSH Vol 8 Issue 12[Year 2017] ISSN 2277 – 9809 (0nline) 2348–9359 (Print) Group of rocks in the area around Rudraprayag, in both Koteshwar and Tilni sections, are characterized by massive dolomitic limestone having dislodged blocks. This rock is observed to show shrinkage features and local folding . Alaknanda Fault (Kumar, 1971) offsets almost all the earlier structures and is a sub-vertical reverse fault dipping towards northeast with angle of dip varying from 25 to 40. Madhyamaheshwar Fault The Crystalline rocks exposed to the north of MCT are traversed by 040°-220° trending Madhyamaheshwar Fault which is observed to extend for a distance of about 6 kilometers from Jaggi to Paundar. Location Map: Seismicity Map of Uttarakhand International Research Journal of Management Sociology & Humanity ( IRJMSH ) Page 310 www.irjmsh.com IRJMSH Vol 8 Issue 12[Year 2017] ISSN 2277 – 9809 (0nline) 2348–9359 (Print) Subdivisions of Himalayas and associated thrust planes in Uttarakhand Source by Google International Research Journal of Management Sociology & Humanity ( IRJMSH ) Page 311 www.irjmsh.com IRJMSH Vol 8 Issue 12[Year 2017] ISSN 2277 – 9809 (0nline) 2348–9359 (Print) Methodology: In the present study critical locations were identified for priority assessment. With the help of Survey of India Toposheets and Handset GPS, locations of studied points were confirmed and the same were marked on the respective Survey of India toposheets (1:50,000). These include change in landscape, landslide and cloudburst distribution map and overburden material map. Lithology and structural data were collected and assessment was made to categorize the landslide. Apart from landslides information regarding localized rainfall/cloudburst events was gathered from the local people and the same were correlated and analyzed. Attempts were also made to assess the causative factors of the damage as to suggest control measures for the stability of affected structures. We have used many such tools which helped in our Field work. Some of the very common tools that I use are named Brunton, Rock hammer, hand lens,