Sunday, January 18, 2009



T. Tashi, Department of Mines, Minerals & Geology

Government of Sikkim, Gangtok-737101, Sikkim


With a total geographical area of 7096 sq. kms., Sikkim is the smallest amongst the North-eastern Council States. It lies between 27000’46” – 28007’48” North Latitude and 88000’58” – 88055’25” East Longitude and has elevation range of 250m to 8598m above main sea level. The State’s increasing population and developmental activities and depleting land and natural resources are in a collision course. Seismic and landslide vulnerability hazard compounds the evolving scenario. Government initiatives are in place to counter and mitigate the existing and perceived negative side effects. Their efficacy is yet to be proved.


The common sight of high relief, swathes of verdant forest, raging fast flowing rivers and rivulets, steep slopes that are under failing and failed conditions, high seismicity and so on characterize the mountain ecosystem of the Sikkim Himalaya. Considering the fragility, diversity and complexity of the existing geoenvironmental settings and the ecosystem, manipulation of natural constants either by nature or man in an unsustainable manner can lead to irrepairable short as well as long term negative side effects and devastation.

The Sikkim Himalaya has never been and will never be free from ubiquity of weak geology, slope instability, frequent seismicity, soil erosion etc. mainly due to natural causes and partly as a result of accelerated degradation. These adverse conditions in tandem can exacerbate the existing fragile, vulnerable and multi-functional mountain ecosystem. So far disasters caused by landslides, earthquakes, floods etc. have not lead to large scale human tragedy in Sikkim in recent memory. However, there is ever increasing human demand of natural resources, especially land for urban development and mega dams in an apparently unsustainable manner, making some of the denizens to adapt and survive at dangerous margins. The emerging crisis can perhaps be minimized by indigenous knowledge based and modern technological interventions. To safeguard against accelerated degradation and improve the living standards of the hill people, the Governments (Centre and State) need to address hill specific issues through systematic and effective integration of the ecosystem services and development, highland and lowland linkages etc. Without a replicable

and hill specific developmental policy, the ever present threat from devastating landslides, earthquake, floods etc. remains and the options and the opportunities of the progeny in jeopardy. A beginning has been made by the State of Sikkim by asking the Department of Science & Technology (DST), Government of India to undertake systematic study of landslide problems in the State. The DST accordingly prepared a status report on landslides in Sikkim. Based on the report, the DST, Government of India, is considering establishment of a multi-disciplinary cell dedicated to landslide studies, not only in Sikkim but the entire Northeastern states. Such a initiative has become imperative because past experience shows that different agencies carry out landslide studies at will and without coordination with each other. Results of such exercises never actually got disseminated and proved futile. Whereas the seismicity monitoring is concerned, site response studies using digital accelrograms located at seven-station-strong motion network in Sikkim by year 2000 and twelve-station network by year 2006 has been done by IIT, Kharagpur and study results are widely published.


Mallet (1875) & Bose (1891) were the first explorers who gave an account of geology and mineral resources of Sikkim Himalaya. Subsequent explorations by Auden (1935), Heim and Gansser (1939), Ray (1947) Ghosh (1952), Raina & Bhattacharya (1975), Raina and Srivastava (1980), Thakur (1986), Ravikant (1993), Neogi et al (1989), Ray (2000) and others gave important and valuable contributions towards understanding of geology of Sikkim.

The current literature describes geology of Sikkim similar to that of the Eastern Himalaya where four distinct geomorphology based transverse zones or tectonostratigraphic domains, separated by major tectonic dislocations, are identifiable. Out of these four tectonostratigraphic units, namely; Sub-Himalaya, Lesser Himalaya, Higher Himalaya and the Tethys Himalaya, the Phanerozoic rocks of the Sub-Himalaya are not exposed in Sikkim. The Lesser, Higher and Tethys Himalaya of Sikkim are typically arranged in a domal shape or arch of thrust surfaces in the form of culmination across Teesta river, popularly known as Teesta culmination (Mcclay, 1992, Ray, 2000). The core of the Teesta culmination is occupied by Proterozoic Lesser Himalaya low grade metapelites of Daling Group of rocks. The distal part is made up of medium to high-grade Proterozoic Higher Himalaya crystalline complex, the Main Central Thrust (MCT) separates the Lesser and Higher Himalaya. Gondovana (Carboniferous to Permian) and Buxa Group of rocks are exposed in the Rangit window zone, small window near Rorathang, East Sikkim and as thrust/fault slices in South Sikkim. The Tethys Himalaya is represented by Cambrian to Eocene fossiliferous sediments of the North Sikkim Tethyan zone which tectonically overlie the Higher Crystalline Complex (see map).


The tectonic frame work and the seismicity of the northern eastern states including Sikkim are considered as a result of collision tectonics in the Himalayan arc and subduction tectonics below the Myanmarese arc. Studies have indicated a very complex tectonic setting of the region due to constant movement of the Indian plate from South to North & Myanmarese from East to West.

The two major structural elements in the Eastern Himalaya are the Main Central Thrust (MCT) and the Main Boundary Thrust (MBT). The Foot Hill Thrust (FHT)/Main Frontal Thrust (MFT) along the Southern edge of the Himalayan bring the Siwaliks in Juxta-position with the thick recent sediments of the Indo-gangetic plain. There are also a large number of prominent lineaments in this region, some of which are reported to extend for several kilometers beneath the Himalayan Foredeep. The Teesta lineaments which pass through Parbatipur area of Bangladesh to Bhadrapur area of Nepal, is considered to demarcate the Western limit of Eastern Himalayan seismicity.

The North Eastern India was subjected to severe shaking by a number of damaging earthquakes. The systematic account of which is available from the middle of nineteenth century only. Besides the Cachar earthquake of 10th January 1869 (Magnitude 7.5), the twenty other severe earthquakes exceeding magnitude of seven and affecting the region during the past hundred years have been tabulated (Ramchandran et al, 1981). Among the recorded earthquakes, the most damaging ones and macroseismically studied are the great Assam Earthquake of 12th June 1897 (M=8.7), Srimangal Earthquake of July 8, 1918 (M=7.1), Dhurbi Earthquake of July 3, 1930 (M=7.1), Assam Earthquake of August 15, 1950 (M=8.6), Assam Earthquake of July 8, 1975 (M=6.7), Cachar Earthquake of December 3, 1984 (M=5.4), Manipur-Burma Earthquake of August 6, 1988 (M=7.3), Assam-Tripura Earthquake of April 13, 1989 (M=5.7) and Manipur Earthquake of January 10, 1990 (M=5.4).

In the Eastern Himalayas, the seismicity is considered as a result of collision tectonics & correlated with the MBF and MCT (Gupta S.K. 2003). The MCT is shown passing through Gangtok to Mangan and then to lower Tolung to north of Sada from where it cuts through North

of Labdang-Tashiding to Gyalshing and then to Kaluk to Soreng before coming out of Sikkim border at an area where it meets the MBF (India-Nepal border).

The IIT, Kharagpur has carried out site response studies using strong motion network of accelerographs in Sikkim during the past ten years. The findings are available in the form of a paper with site response contour maps (Nath, et al 2000) and a paper with microzonation maps (Nath, et al 2006).

The existing record shows (Table 1) that the state has been subjected to local earthquakes of M=5.0 to M=6.5 and non-local high magnitude earthquakes of above M=8.0 (1897 and 1950 of Assam), (1934 of Bihar). The whole of the State is therefore, has been slotted in Seismic Zone IV of IS:1893-1984 and categorized as High Damage Risk Zone of MSK VIII.

Considering the seismically vulnerability of the State all new constructions are subjected to strict observance of BIS codes or seismic codes. The existing unsafe and non-engineered building stock still remains and is practically impossible to address the entire such building stock. The alternative left is to retrofit only the life line buildings such as hospitals, schools, cinema halls, multi-storied hostel/apartments etc.


Mass wasting processes are a universal phenomina in mountain, hill and hilly areas of the world. Their magnitude, frequency and type differ from place to place and on the material that is undergoing displacement either through chemical or mechanical means. In the Himalayas, mass wasting process is dominated by landslides. The magnitude, intensity and frequency of Himalayan

landslides vary from East to West and from South to North. The variation is controlled, mainly by climate, neo-tectonism and seismicity. The eastern Himalaya including Sikkim is a hot-spot for natural hazards, particularly landslides and earthquakes.

Landslides of all types and size occur in almost all types of rocks and quaternary formations of Sikkim. The Daling Group of rocks, especially, Gorubathan Formation appears more prone to landslides than the inhomogeneous quaternary deposits and gneisses and schists of Higher Himalaya. The high landslide susceptibility of the Daling Group of rocks has been attributed to their severe shear distortion due to loading and unloading during orogenesis, higher rate of weathering and mineral composition. A cursory survey of frequency of occurrence of landslides in Sikkim was done in 1991 and the result clearly showed that the East and South Districts where Daling rocks dominate are affected by maximum number of landslides (Table below)






























(* only prominent ones)

Almost all the landslides in Sikkim occur after prolonged exposure to monsoon rains and occasionally during or just after cloudbursts or precipitation intensity exceeding 135-145 mm in 24

hours. The red letter month of October 1968 was considered the most disastrous month in recent years of Sikkim history. On 5th September 1995 heavy rain triggered off a mud avalanche near Gangtok killing 32 people. Similarly, non-stop heavy rain since early June 1997 damaged 300 houses completely, 1000 houses partially and caused death of 51 people in East and North districts of the State. Rain, therefore, has been one of the main triggers besides weak geology, steep slopes with thick overburden, frequent earthquakes etc., causing landslides.

There has never been a systematic study of landslide problems in Sikkim. Most of the existing literature on landslides of Sikkim are written by some fancy expert expatriate on a whirlwind visit to the State. Since no two landslides are identical in any given area, it is not always easy to know the ground realities of mechanism to trigger off landslides. The State Department of Mines, Minerals & Geology, took up a number of landslide prone and affected areas for systematic study and mitigation measures. Besides treating some chronic rotational type of landslides along State highways with slope dressing, benching, installation of effective drainage systems and so on, some planar type slides, controlled by joint, foliation and bedding planes were further subjected to grouting and rock bolting, both tensioned and untensioned (see pics). The notoriety of a landslide is known by its maximum capacity to cause damage to life and property. Some of the well known landslides falling in that category are as shown in Table 2. Sikkim being a land locked State, disruption of road communication by landslides is an annual affair. For every linear kilometer of Sikkimese road there are atleast 10 minor to major slips.

Tensioned Rock Bolting

Tensioned Rock Bolting


Natural hazardous events such as earthquakes, landslides, floods etc. in the Himalayas are a reality. Man and man-made structures stand no chance against the awesome power and fury of such events when they strike. Therefore, a mechanism is needed to safeguard against massive and unwarranted loss of life and property in the event of a calamity. In August 2004, the Government of India came out with a detailed status report on Disaster Management in India. The report specifies various programmes and strategies of the Nation to tackle and mitigate all forms of destructive natural events. Translation of some of the recommendations have already begun in Sikkim. The Department of Land Revenue & Disaster Management, Government of Sikkim and UNDP has undertaken various initiatives in this direction. The general public is sensitized through awareness training/talk shows, mock drills, banners and so on. The North eastern states including Sikkim being in high seismogenic domain, landslide and flood prone areas require special attention and constant vigilance. The on-going research by established institutions in various fields of adverse events needs up-gradation and monitoring by an apex authority for proper and effective coordination of long term research and dissemination of information to stake holders. The existing scenario of haphazard and secretive study of natural events by all sorts of agencies needs to be discouraged.


About Mr Tshering Tashi :-

Mr Tshering Tashi is a 55 yr old geologist who is Director (Dept. Of Mines, Minerals & Geology) Govt. of Sikkim. After completing his school in Tashi Namgyal Academy, Gangtok, he went onto do his M.Sc,(Applied Geology)from IIT, Kharagpur and M.S. (Geology) from Univ. of Colorado(USA).

I know him personally and when he is not immersed in work he is a fun loving person who loves fishing or just relaxing with his family.

praful rao

Thursday, January 8, 2009

A shameful saga (RTI ignored)


I had submitted an application to the State Public Information Officer, Office of the District Magistrate on 19Aug2008 (under the Right to Information Act 2005) seeking certain information as regards Disaster Management in the Darjeeling District. After taking up the issue with the State and National Information Commissions and after the State Commission served them a show cause notice (see blogs of 06Dec08 and 01Jan09), I was finally faxed a reply to my RTI application,almost 5 months after I filed my questionnaire (Copy of FAX is reproduced above as EXHIBIT 1)
I have reproduced the questions which I asked and the replies (in red Italics)recd below:-

The reply to my RTI application makes a mockery of both Disaster Management and the RTI Act2005. Undoubtedly we will be pursuing this issue further.

Office of the District Magistrate,
Darjeeling Date : 19Aug2008

Application under Right to Information Act 2005

Kindly provide the following information with respect to landslide hazard prevention and mitigation in Darjeeling District:-

1) Was a survey carried out by the District Disaster Management Authority (DDMA) to determine the exact extent of damage due to landslides and identify high risk areas in Darjeeling district following the exceptionally heavy rainfall in the first week of Sep2007?
If “YES”, please furnish details and findings
If “No”, please give reasons.

No, DDMA was formed in this district till date. But survey on landslide areas in Kalimpong Sub-Division
was held several times.

2) Please furnish details of any landslide prevention work done in high risk populated areas (such as Alaichikhop, Dr Graham’s dispensary area in Kalimpong and Harsing, Lebong in Darjeeling and Baggaora in Kurseong)after Sep07 to mitigate/prevent any landslide that might occur ( this work would essentially have been short term fire-fighting measures such as jhora training / drainage repair etc).

Will be sent later on

3) Please furnish details of landslide prevention and mitigation work carried out in Darjeeling district in the last 5 years.

Will be sent later on

4) Please specify for the last 5 years:-
a) Total fund allocation for Disaster Management in West Bengal.
b) Fund allocation to Darjeeling district for this purpose.
c) Amount spent on landslide prevention and mitigation.
d) Areas where major landslide prevention work was carried along with expense details and year when the
work was carried out.

a), b), c), d) under process

e) Details of landslide awareness programs carried out in the district by the DDMA.

Awareness programme relating to landslide was scheduled to be held by State Disaster Management Authority on 27.11.08. But due to unavoidable circumstances the programme could not be held.

5) Please furnish details of your short/ mid/ and long term plans regarding landslide hazard prevention and mitigations in the district in the future.

Landslide prevention work will be done by the respective departments as per G.O. No 128 PR dated 16.1.08 (copy enclosed) and this has been informed to all concerned vide this office Memo No. 121/DMS dated 28.3.08

I am depositing Rs10/- as application fee.


praful rao

Monday, January 5, 2009

The way forward - An update on planned STH activities

a) Dr RK Bhandari {former Chairman/ founder of Centre of Disaster Mitigation and Management (CDMM), Vellore Institute of Technology and perhaps the foremost expert on landslides in the country} who has been a strident supporter and also adviser of STH has been contacted. He has asked STH to get in touch with CSIR (Council of Scientific & Industrial Research) and Ministry of Earth Sciences and send them a letter of STH activities and ask for help (for awareness programs etc). He said he would also put in a word for STH with these agencies.

b) Shri KM Singh, Member NDMA who is in charge of the National Disaster Response Force (NDRF) in the NDMA has been contacted. He said he would help regarding, a) Printing publicity material as regards landslide hazards thru NDRF resources. b) Sending NDRF personnel to participate in awareness programs as regards medical first response in landslide disasters.

c) The Director of Cinchona plantations (Dr Gyan Subba) in this region has been contacted. When we talked to him, he was most aware and positive about STH activities and asked me to include the Cinchona plantations in the awareness workshops...he would extend whatever help was possible.

d) Mr Amit Khasnawi is the Officer in Charge Civil Defence, in Kalimpong, and he contacted us sometime ago regarding STH. As we all know the civil defence plays a major role in all rescue operations in a post disaster scenario. STH (Kalimpong) has a meeting with him today to find out how our activities can be integrated with those of the Civil Defence.

e) Dr Sanjay Rana (North Bengal Univ), Dr Subir Sarkar (Head of Dept, Geography - North Bengal Univ), Dr Varun Joshi (Head of Dept, Disaster Management- GB Pant Institute, Gangtok and Mr Manav Prasad, Commander, 764 BRTF, Mr Tsering Tashi, Director Mines, Sikkim have all been contacted in the last few days with a request for articles as well as advice, support, inputs for STH activities. All were very positive.
Besides this ,Mr Trilok Kr Dewan (IAS), former Chief Secretary Andhra Pradesh, now a resident of Darjeeling, has also talked to concerned officials in Delhi regarding the landslide problem in these hills.

f) Mr Suman Rai of ATREE (Eastern Himalayas) has always been an ardent supporter of STH activities. We have invited him over tomorrow for a meeting with STH (Kalimpong). He has kindly agreed.

praful rao

Thursday, January 1, 2009

The light at the end of the Tunnel?

Further to the earlier post dated 06Dec2008 on the RTI application.
I had asked some questions way back in Aug2008 (SLIDE 1) regarding landslide prevention measures in the district....
questions to which I have yet to receive answers despite the West Bengal Information Commission having intervened in Oct2008 (SLIDE 2) and directed the State Public Information Officer (SPIO) at the District Magistrate's office in Darjeeling to answer the relevant queries "within 15 days".
Two days ago I received a copy of the show cause issued by the State Commission to the SPIO, Office of DM Darjeeling (SLIDE 3) on 18Dec2008... the deadline ie "within 7 days of receipt of this letter" is again long passed, nevertheless I see a light at the end of the tunnel.
The press coverage in the Telegraph is reproduced below :-
Info glare on officer

Kalimpong, Dec. 31: The West Bengal Information Commission has showcaused a public information officer for failing to provide disaster management-related information to Save The Hills (STH), an NGO.

In its notice dated December 18, the commission has asked the state public information officer of the disaster management authority, posted in Darjeeling, to explain within seven days from the receipt of the letter why he has failed to respond to the queries of Praful Rao, the president of STH.

It has also threatened to impose penalty on the officer according to the provisions of the the Right to Information (RTI) Act. Under Section 20 of the act, the failure to comply with an RTI request can lead to a fine of Rs 25,000 as well as disciplinary action.

The Kalimpong-based organisation, through an application under the RTI Act on August 19, had sought to know the long and short-term measures contemplated by the district disaster management authority to mitigate landslide hazards in the district. The NGO had also wanted to know whether or not most landslide-prone areas had been identified and the money allocated and spent on disaster management in the district.

Rao said he was compelled to approach the state commission after the district authorities failed to respond within the stipulated one-month period. “Hopefully, something positive will emerge from the commission’s notice,” he said.

Describing the RTI Act as an effective tool to extract information from the government, Rao said STH’s experience had shown that it was almost difficult to get it on time.

“The RTI Act stipulates a time limit of 30 days for questions to be answered, but even after more than four months of submitting the application, we are yet to get any response,” Rao said.

The NGO was formed after landslides caused severe damage in the hills in September last year.

When contacted, the information officer, Biswanath Barik, said: “We have received the notice. We will respond to it in the next three-four days.”


Comment by praful rao

My thanks to Mr NP Dixit, President Citizen's Right Forum, Kalimpong for having written to the State Commission on behalf of STH