Saturday, October 29, 2011

Quake report : 29Oct2011

Date of Occurrence:
06:13:41.0 HRS(IST)
Lat. 27.4°N Long. 88.4°E

Source :

No loss of life or damage reported

Praful Rao

Thursday, October 27, 2011

Affordable & effective means of erosion control/slope stabilization

Whereas traditional engineering methods (such as gabion retaining walls, river training etc) and new technologies (see here) for landslide mitigation and soil erosion control are effective, most are exorbitantly costly, requiring huge investments.
Placed above are some other methods of slope stabilization which are much more affordable and therefore do-able at the community level and which are also very effective.
For those interested some more literature on use of jute geotextile and bamboo check dams for slope stabilization are here (1 & 2) and most of the 10,000 saplings of vetiver grass that we planted  in the monsoons are doing well. Next year we plan large scale plantation of this grass in this area.

Photo credits : Suren Chhetri (Tindharia) and self

Praful Rao

Friday, October 21, 2011

Picture of the day :20Oct2011 (Water Crisis in Kalimpong)

As the placard carried by the retired policeman suggests the water crisis in Kalimpong is largely due mismanagement, a faulty distribution system and huge amount of leakage which is never rectified - this was further exacerbated, when some pipelines were damaged by landslides in Sep2011.
Availability of potable water is already a huge crisis in many towns all over the Himalayan region as natural springs dry up due to a variety of reasons . As demands increase, due to burgeoning population and tourism, contractors supplying water from dubious & untested sources are thriving whereas little thought is being given to long term solutions to a disaster in the offing.

Praful Rao

Tuesday, October 18, 2011

STH stormwatch : Trouble brewing in the Bay (18Oct2011)

Excerpt from IMD midday bulletin

The low pressure area over eastcentral Bay of Bengal now lies as a well marked low pressure area over eastcentral and adjoining westcentral & northwest Bay of Bengal with associated upper air cyclonic circulation extending upto midtropospheric levels. The system may concentrate into a depression during next 24 hours.

  • Widespread rain/thundershowers would occur over Nagaland Manipur, Mizoram and Tripura.
  • Fairly widespread rain/thundershowers would occur over Arunachal Pradesh, Assam & Meghalaya, coastal areas of Gangetic West Bengal & Orissa, Tamil Nadu, Kerala, Lakshadweep and Andaman & Nicobar Islands.

    Praful Rao

Quake report : 17Oct2011

Date of Occurrence: 17/10/2011
Time: 18:34:50 HRS(IST)
Intensity: SLIGHT
Magnitude: 3.5
Epicentre: 27.3 N,88.4 E
Region: SIKKIM

Source :

No loss of life or property reported

Friday, October 14, 2011

All about rainfall

End of the Monsoon report (excerpts from IMD report)
  • For the country as a whole, the rainfall for the season (June-September) was 101% of its long period average (LPA).
  •  Seasonal rainfall was 107% of its LPA over Northwest India, 110% of its LPA over Central India, 100% of its LPA over south Peninsula and 86% of its LPA over Northeast (NE) India.
  • Four depressions formed during 2011 monsoon season as against the normal of 4-6 monsoon depressions per season.

    The Flood Meteorological Office at Jalpaiguri (W Bengal, India) has signed off its operational watch from 14Oct2011 due to withdrawal of the SW monsoons from the Sikkim & W Bengal region.

    Praful Rao

Thursday, October 13, 2011

An article from 'The Hindu'

Periphery shaken by Centre's neglect

Recalling the September 18 earthquake, Sikkim University Vice-Chancellor Prof. Mahendra P. Lama says the hill areas lack sensible disaster management.
Interview of  Prof Mahendra P Lama, in
The Hindu of today.
What are the lessons learnt from the September 18 earthquake that left a trail of devastation across Sikkim?
There are quite a few lessons we have learnt from this calamity. Firstly, our ability to cope up with natural disasters is still very nascent and limited.
We have not developed any formal institutions in this regard in the real sense of the term. More seriously, we suddenly realised that the robust system of community-based, voluntary management of natural calamities which remained the most pre-dominant phenomenon for centuries together is also fast vanishing. Today the disaster management task has become government centric whereas traditionally it used to be essentially community centric. Many of the States including Sikkim still do not have proper disaster management plans. We, therefore, must rethink our strategy.
Secondly, the communication system and other physical connectivities are also in a state of infancy despite so much of plans and projects.
Thirdly, the entire development dynamics in the mountain areas need to be reconsidered and reoriented in view of the fact that the casualties and destruction could be unprecedented and unmanageable if such calamities recur.
Fourthly, scientific studies and research on issues like seismology, hydrology, geo-morphology and the very nature and dimensions of natural disasters and their impact on the hills and mountain areas need to be strengthened and disseminated to the people at the grass roots. This has to be blended with traditional wisdom and belief about the impending disasters so that the communities are involved in disaster forewarning and management.
And finally, each disaster in the mountain areas is intensely integrated with other national interest issues including national security, physical dislocations and environmental injuries. This is more so as these theatres of disasters are located in the geo-politically sensitive border locations.
How can the challenge of roads blocked by landslips, hampering relief and rescue missions in States like Sikkim, be overcome?
Massive concrete-based development works that go in the mountain areas pose a serious threat to the carrying capacity of these roads. Unless the entire road construction contracting system is reviewed and a five-year guarantee is ensured by these road agencies with strong punitive measures; and techniques like covering toe-cutting edges of the streams and rivers down below is used, the situation is going to be more pathetic and vulnerable. All these are time consuming and demand a lot of engineering wisdom and precision.
Key agencies like the Border Roads Organisation have to rethink both the techniques and technology of road building in the mountain areas. Two very vital traditional wisdoms on road building in the hill and mountain areas have been blatantly ignored. Firstly, the road has to have a drain on the hill slope side so that the water trickling down can be channelled. Secondly, the sinking area requires very careful maintenance and rocks and mud pouring to fill up the sinks must be avoided.
The basics of disasters and their management have to be taught at the village and community levels and also in all the educational institutions.
Universities, with their colleges and other outreach programmes, could in fact be a major bastion for disaster related studies and management.
What role do you envisage for the government, people and private players for effective disaster management?
This disaster has again brought forward the critical issue of connectivity — both physical and virtual — in the Northeast and the mountain areas. This has to be seen in the context of both centre-periphery disconnects and deprivations, say between Delhi and Meghalaya, and also in the larger context of national security needs. This region provides comprehensive security to the nation. However, the blatant lack of political sagacity, absence of bureaucratic resurgence and the feebleness of the civil society to do something substantive and leap-frogging for this region has eaten into the vitals of this so-called Indian periphery.
We are not only ill-prepared but also myopic in our thought process. One accident or a small landslip could dislocate the entire national highway for hours and sometimes days together. Disasters only shake us and do not wake us up.
For us in this region, BSNL is another white elephant. It just does not want to move an inch from its routine activity and tunnel-like thinking. The role of private players in the aftermath of the earthquake needs to be thoroughly inquired. The communications stopped working when you needed it most. We need to really delve into their social responsibilities and make them sensitive and robust to cope with unforeseen calamities.
Popular perception is that the multiple dams on the Teesta have adversely affected the fragile ecology of Sikkim and induced seismicity.
Energy is required for national and local development. For that, a potential renewable source is the unharnessed rivers flowing in the mountain areas. If done properly it can transform the entire development dynamics in the region. Bhutan is a good example.
People are not against the hydel power projects as such. They are against the way these projects are done, the casualness with which the environmental impact assessment is conducted and clearances are given and the way project developers are selected. The location, size and scale of these projects, the knowledge and experience of these project developers, the capability of project regulating agencies and the way projects have been designed and the technology used have been questioned all across the fragile Himalayan ecology. Unfortunately, in many cases these issues come up for public discussion only in the aftermath of disasters.
What are the short-term and long-term impacts of the disaster on Sikkim's economy and growth prospects and what needs to be done now?
The short-term impacts are, of course, the scar on ordinary people's psychology about the fear of recurrence; the time and resources taken to rebuild the devastated areas; disruption in the flows of tourists and other productive activities; and the disengagement of governmental machineries from their regular delivery systems and governance. The long-term impacts are more in the form of formidable challenges in terms of material and service demands on the State and the government; reorienting the development strategies; refurbishing and implementing the building regulations and proper urban planning; checking on the quality of construction works; integrating the system with agencies like BRO and GREF and several other central agencies like the Geological Survey of India.

Praful Rao

Saturday, October 8, 2011

Look, Ma! - no Cyclones!

Cyclones, depressions and low pressure areas which form in the Bay of Bengal usually cause periods of intense, heavy downpours which result in landslides in the Darjeeling-Sikkim Himalayas. As such STH has been plotting/tracking these phenomena on the Internet for some time now (see 1, 2, 3, 4 & so on) .
A record of the cyclones which brewed up in the Bay of Bengal in 2010 (with date and surface wind) is placed above and what is absolutely amazing is that in 2011, we have not had a single cyclone forming in the Bay till date and the number of depressions which have formed is also below normal.
All this when the Philippines has been hit by 3 major back-to-back typhoons within the last one week!
But then our cyclone season lasts upto December ....
For those interest please find below the Classification of bad weather phenomenon as per the IMetD :-

Classifications of cyclonic disturbances for the north Indian Ocean region are given below:-

Weather system                               Maximum wind speed
1. Low pressure area…………………..Wind speed less than 17 kt (31 km/h)
2. Depression………………………….. Wind speed between 17 and 27 kt (31 and 51 km/h)
3. Deep Depression…………………….Wind speed between 28 and 33 kt (52 and 61 km/h)
4. Cyclonic storm ……………………….Wind speed between 34 and 47 kt (62 and 88 km/h)
5. Severe cyclonic storm……………… Wind speed between 48 and 63 kt (89 and 118 km/h)
6. Very severe cyclonic storm…………Wind speed between 64 and 119 kt (119 and 221 km/h)
7. Super cyclonic storm ………………..Wind speed 120 kt (222 km/h) and above

Praful Rao

Wednesday, October 5, 2011

From the Bengal Post - The Earth shook & all hell broke loose

The Sikkim Earthquake is a prelude to bigger disasters. Constructing even concrete houses in the region is fraught with risks.

The Darjeeling-Sikkim Himalaya sits in a seismically high-risk zone. This was a fact that almost everyone in the hills has known fora while. However, there is no record of any great earthquake (less than7.0 Richter scale magnitude) in the history of the Darjeeling-SikkimHimalaya. This led to a sense ofcomplacency in the hills and urbanisation and development mushroomed. The “Ikra” Assam type houses gave way to “plainstype” flat- roofed multi-storeyed concrete houses that were more often than not built by slicing-up hill-slopes like “tosh-roti” (bread) or on precariously balanced stilts on hill slopes. Those who were aware shivered at the very thought of a great earthquake occurring in the Darjeeling-Sikkim Himalaya and collectively yelled from every available roof-top about the earthquake hazard and the associated disaster we were like to face.
Nevertheless, dams are being built on the Teesta, tunnels are being driven deep into the hills of Darjeeling-Sikkim based on the fact that the largest earthquake that the Darjeeling-Sikkim Himalaya recorded before September 18, 2011 was of a magnitude of 6.2 earthquake on November 19, 1980 which did not cause much damage. As Seismic Zonation is done on the basis of the highest magnitude earthquake recorded in a region, the Darjeeling-Sikkim Himalaya was put at IV rather than V.
This made sense till the mid 1990s when Global Positioning System (GPS) came along and changed the whole game. The Global Positioning System allows us to measure positions on the surface of the earth very accurately and also determine how much the point is getting displaced over time. This information gets translated into surface velocities that give us an insight into how the ground is moving even when earthquakes are not being recorded. GPS measurements tell us that India is moving like a car towards Northeast at about 5 cm/year and slamming into a wall-like Tibet in extreme slow-motion along the Himalayan boundary that decelerates it from 5 cm/year at Bangalore to 4.7 cm/year in North Sikkim; the Himalaya is the front end of this colliding and continuously crumpling car. The difference of 0.3 cm of motion is being absorbed into the Darjeeling-Sikkim Himalaya as strain energy every year since millions of years. The accumulated strain keeps getting released as earthquakes when it crosses a particular threshold determined by the strength of the rocks. Given this fact, not experiencing a great earthquake is not good news. It merely points to the fact that the strain that has gone into the Darjeeling-Sikkim Himalaya has not been released in a significant manner.
The front-end of the colliding car has not finished crumpling! Every new crumple results in a major earthquake. This is the backdrop against which the September 18, 2011 earthquake occurred.
The good:
There were a number of good things about this earthquake. First, its epicentre was located in the Kanchenjunga Range far away from populated regions and not in Mangan. So, the location of the epicentre was fortuitous. Second, the earthquake was a moderate 6.9. Not quite a great earthquake but, as Bharat Mani Pradhan put it, “Powerful enough to shake us and hopefully stir us into some action”. The third good thing about this earthquake was that it was a strike-slip earthquake which is basically similar to the motion of rubbing your hands when held vertically. In terms of the colliding car, it was not a new crumple developing in its front end but just a big scrape on its side during the process of frontal head-on collision.
Would the scrape on its side slow its forward motion and prevent new crumple zones from developing? That is a question that future GPS measurements will be able to address. For now, we have to view this earthquake as a wake-up call and get our act straight.
The bad: It is obviously the confirmation of our worst fears and the resultant death and destruction that was caused by the earthquake.
Reinforced cement concrete (RCC) buildings are bad in seismically active zones. The risk of having concrete over our head was established beyond doubt for Darjeeling- Sikkim during this earthquake. Earthquakes also trigger landslides and the double whammy of earthquakes and landslides is something we have to be aware of, expect and plan for in Darjeeling-Sikkim. The less we mess around with intact rock in widening roads or tunnelling deep into the mountains, the better. The fact that tunnels collapsed in Chungthang and multiple landslides impeded the ability to transport relief and rescue teams has to be viewed with extreme seriousness. An honest evaluation of the performance of the dams during the earthquake must be carried out to assess how they will behave when earthquakes of higher magnitude strike the Darjeeling-Sikkim hills. Will the dams increase the speed of our colliding car and cause it to crumple sooner? That is again a question that needs to be revisited in the aftermath of September 18, 2011. The earthquake has forced us to address some tough question sooner rather than later.
The ugly!: This has to be the realisation that we are grossly under prepared to tackle a calamity that would descend upon us if a great earthquake with an epicentre in the Teesta Valley would strike us. Also, it confirms what GPS results are telling; the Darjeeling-Sikkim Himalaya is continuously getting strained and it is only a matter of time before we get a great earthquake. The ugly truth of the situation is that we cannot predict earthquakes in human time-scales because the processes in the earth operate in a super-slow mode spread over millions of years. However, science is letting us know that we are overdue for a great earthquake in our space. The other ugly part of the situation is that a vast majority of us have already committed our lifetime’s savings into constructing the spacious and “pucca” RCC dream houses. Can we financially afford to abandon the houses that we have built even after the realisation that we may be living in buildings that may end up being tombs? Like it or not, we have to make very tough personal decisions. We have to decide if we want to risk it all and continue to live in our RCC houses and hope that we can find a “triangular space of life” in our collapsed concrete structures when the big ones strikes. A real “Ram Bharose” or “whatever will be, will be” existence as Wing Commander Prafulla Rao put it. The other choice is to cut our losses and go back to not having concrete over our heads. That is the tough and ugly personal choice each and every one of us will have to make. The least we can do is to not build any new concrete over our heads and keep the earthquake hazard in mind when making decisions on all future developmental activities in the Darjeeling-Sikkim Himalaya. We owe it to each and every person who had to sacrifice their lives on September 18, 2011 to give us this wake-up call and this lesson. This has to be the lasting legacy of this tragic event and the best way to pay our respects to those who were taken away from us on September 18, 2011.

- Published in the Editorial of Bengal Post (04Oct2011)

Dr Malay Mukul is an ex-student of
Dr Graham’s Homes, Kalimpong & is presently
Associate Professor,
Department of Earth Sciences,
IIT (Mumbai)
Praful Rao

Saturday, October 1, 2011

To insure or not to insure (your home)

One of the after effects of the 18Sep2011 earthquake in our area will be that the insurance companies will be thronged by people who will want to insure their homes or buildings against earthquakes and maybe landslides. This is a good thing and I strongly advise insurance of homes and assets.
However, a word of caution - insurance companies can be tricky people and not all of us have the time or patience to read the small print in the "terms and conditions", so more often we end up signing on the dotted line and leaving the rest to the insurance agent.
Having had personal experience of this earlier, here are some words of advice :-

  • If possible visit the insurance company office, talk with the Branch Manager and ask him to send an agent who is responsible and a good service provider.
  • When the agent arrives, confirm that the insurance policy covers landslide and earthquake damage. (A reputed insurance company representative told me last week that they may stop insurance against these hazards in this area since we are in a high risk zone and they would lose large sums of money if they continued the insurance)
  • Confirm that the retaining walls of the house/building will also be covered by the insurance.
  • Check the depreciation that will be levied on your building/structure and be sure that old buildings will be valued at considerably less than what you might think!
  • While filling up the insurance papers, be specific and list each building/structure separately – with dimensions.
  • Some companies require details of contents of the building/home to be listed out before insuring –provide this information if necessary.
  •        Ask the insurance agent  about the procedure to be followed in case of claim :-
o                   An FIR is to be made at the police station immediately after damage.
o                   Land ownership documents and site plan will be required.
o                   Approved building plan also will be required.
  •  When your building is damaged, intimate damage on telephone and writing immediately to the agent and Insurance Company office. DO NOT START REPAIRS.
  • Photograph all damages and cracks with a camera which has a date stamp.
  • On getting your intimation, the company will send a representative to assess the damage. Discuss the claim procedure with him and commence repairs only after getting his clearance. Go thru the claim form that he hands over to you and clarify any doubts. You will require an engineer to be available to prepare an estimate of the costs.

    Comment by Praful Rao
    Would appreciate any comment on the above since financial wizardry is not exactly my forte...