Friday, December 30, 2011

STH stormwatch : Cyclone Thane, first cyclone (and last) cyclone of the year in the Bay of Bengal


Incredibly, as the year draws to an end, the first and most certainly the last cyclone to form in the Bay of Bengal in 2011 has made landfall on the shores of Tamil Nadu.
It is just this sort of weather phenomenon that STH along with IMD (Sikkim) has established an SMS based early warning system which worked well in 2011 and which we hope to expand in 2012

Tuesday, December 27, 2011

At the year end , a sombre warning and a typical reaction - denial and disbelief

News report on the American Geophysical Union (AGU), Fall Meeting 2011, San Francisco, 05-09Dec2011

Experts Call For Valley’s Micro-Seismic Zoning

Srinagar, Dec 9: A study by a prominent US based seismologist has warned that Kashmir Valley is likely to be hit by an earthquake of largest ever magnitude. But the study does not specify any particular time-frame.

However, the Kashmir based experts recommend the state government to undertake micro-seismic zoning in the Valley to minimize loss of human lives in case of any such eventuality.
The study conducted by Roger Bilham, a seismologist and professor of Geology at the University of Colorado at Boulder US, states that the major quake with magnitude 9 is likely to trigger landslides that would dam the Jhelum river, which drains from the Kashmir Valley into Pakistan.
“That could put the Kashmir Valley under water within three months - and would also threaten disastrous flooding in Pakistan if the waters were released too quickly. The two nations should develop a cooperative plan to deal with the aftermath of a Kashmir mega-quake,” Prof Bilham states in the study.
Prof Bilham states that his new Global Positioning System (GPS) data readings revealing the gradual movement of rocks in the Zanskar Mountains north of the Kashmir Valley show that earlier estimates of the maximum possible quake in the region were too low.
“In this region, the Indian plate is slowly burrowing under the Tibetan plateau. Studies on where the relative movement of the Tibetan plateau was slowest, indicates where compression is building up, and a rupture is eventually likely to occur. I expected this to be in the Pir Panchal range, to the south of the Kashmir Valley, but instead it was in the Zanskar range to the north.”
“This means that the zone likely to rupture when a quake eventually happens could be 200 kilometres wide, rather than about 80 kilometres, as was previously thought. The zone would encompass the Kashmir Valley - including the city of Srinagar, home to some 1.5 million people. If slippage occurs over a length of 300 kilometres, as is possible, a mega-quake of magnitude 9 is the likely result. Given building codes and population in the region, that could mean a death toll of 300,000 people,” the study states.
Pertinently the 9-magnitude earthquake which hit Japan on May 11 this year devastated the country.
Bilham points out in the study that seismologists have been caught out by recent mega-quakes, including the 9-magnitude Tohoku quake that hit Japan in March, by basing their estimates on historical patterns, rather than physical measurements. “I think you have to plan for the worst case,” he says.
Bilham revealed his findings at the American Geophysical Union meeting in San Francisco this week.
Prof Muhammad Ismail Bhat, former Head Department of Geology & Geophysics at the University of Kashmir said the earthquake of 9 magnitude can be catastrophic for the Valley.
“We have seen the impact of 7.6 magnitude earthquake in 2005. According to the study, a new fault has been identified in Simthan and Shopian side. It is an active fault. The problem is that we don’t have the relevant data to identify the earthquake vulnerable zones. It is high time for undertaking micro- seismic zoning across the Valley to identity the places which are vulnerable to earthquakes,” Prof Bhat said.
Prof Shakeel Romshoo, Associate Professor, Department of Geology and Geophysics however, said there is no mechanism to predict earthquakes. “But it is a known fact that Himalayas in Kashmir are tectonically active and highly vulnerable to earthquakes,” he opines.
Kashmir is placed in seismic zone five, making it highly vulnerable to earthquakes. Incidentally, the Valley was hit by a 7.6 magnitude earthquake with its epicenter in Muzaffarabad in Pakistan-administered-Kashmir causing massive destruction of life and property in the affected areas.
In August this year, five tremors of moderate intensity were recorded in the Valley with one of them having its epicentre in Jammu and Kashmir. The earthquakes occurred from August 19 to 23 with magnitude ranging between 4.8 to 5.1.
Prof Bilham who has been studying the earthquakes in Himalayan region for past 20 years, had visited Kashmir in 2007 alongwith Dr Susan Hough of US Geological Survey, Pasadena California.
They had interacted with experts here and recommend many measures including identifying locations of future earthquakes, research effects of historical earthquakes, determine their recurrence intervals and educate common masses and people associated with construction about measures to limit losses and save lives.
However, most of the recommendations are yet to be implemented. “We don’t have funds to implement the recommendations or undertake more research on earthquakes in Kashmir. The Government only act when a disaster strikes. Till then it is in a slumber putting the lives and property of people at risk,” said a senior seismic expert of the Valley wishing anonymity.
“The State Government is not prepared to deal with any eventuality arising out the earthquakes. It is high time for the concerned authorities to take the study seriously and gear up to meet any eventuality,” he said.
When contacted officials associated with Disaster Management Cell of Kashmir refused to comment on the issue.

A typical reaction to the above warning is the one given by Pakistan Meteorological Department, Director General below :-

“Talking to this scribe PMD Director General Arif Mehmood played down the findings about any major earthquake in the Kashmir region and said the recent earthquake in Haiti is a grim and embarrassing reminder that seismologists cannot predict earthquakes.
He said if anyone predicts major earthquake anywhere in the world it means he tries to over-simplify a much complicated issue because there is no evidence in the recorded history that anyone was able to rightly predict any earthquake before its occurrence. “The researchers have been doing hectic work and may be sometime in future we are able to rightly predict earthquakes but at the moment I am not ready to believe any such prediction because no science or methodology is yet available to do so,” he said.”
Comment by Praful Rao
Having just gone thru 6.9R earthquake recently and with predictions that we may expect another big one in this region , I find the above reaction of the DG, Pakistan Met Department a typical one, which I am sure we in India share whole-heartedly.
And so rather than work  urgently and proactively towards disaster preparedness.we prefer to live in a world of denial and disbelief.

You may read a more about the AGU meet in San Francisco (USA) here

Monday, December 26, 2011

Earthquake activity in Darjeeling-Sikkim Himalaya - Dec2011

As per IMD there were no earthquakes in the region in Nov2011.

Source of above report is here

Praful Rao

Saturday, December 3, 2011

Excerpt from Sikkim NOW! (27Nov2011)

Stability drastically degraded, future threats present major challenges

Study of 150 earthquake-induced slides flags 12 for urgent attention and recommends longterm measures for another 32. Disaster preparedness plans should seek out local inputs

GANGTOK, 27 Nov: With more than 150 landslides triggered off all over the State by the 18 September Earthquake, there is now genuine concern over the stability of the soil and rock formations and whether they will be able to withstand the next monsoon. Concern over the safety and security of life and property in the coming seasons has become a top priority with the State government now with the Mines & Geology Department reporting that there are likely to be numerous slides next monsoon as the slopes and hill sides have been destabilized and considerably weakened by the impact of the earthquake. Not just landslides, there is also a threat of glacial lake outbursts in North Sikkim.

According to the report, “The overall stability of land and rock mass has undergone drastic degradation. Keeping in view the changed scenario, the safety of life and properties is of great concern in years to come. The challenging task is to unravel the threat that is likely to be encountered in future.”

The report, which was recently submitted to the government, informs that numerous cracks have developed on the slopes throughout the State; with Sikkim being a terrain where landslide and slope modification process are still active, the risk and probability of earthquake induced landslides are very high.

Not just landslides, there is also the danger of mass mobilization. As the report states: “Due to the impact of recent earthquake, the risk of landslide and mass mobilization has risen to alarming stage and disaster mitigation task will be a challenging task for the future before the onset of next monsoon”.

The preliminary investigation, on which this report is based, identified more than 150 earthquake induced landslides out of which 12 landslides are reported to need urgent attention and another 32 slides identified for long term measures. It was observed by the experts during investigations that the impact of the earthquake was more pronounced on crystalline rocks mainly on its quartzites and variants with adverse slopes and on landmasses adjoining steep slopes and water-ways.

Short term measures recommended by the officials include soil compaction on fissures on landmass to minimize seepage and use of local technologies to retain unstable boulders. Apart from recommending identification of risk areas, it is also proposed that a disaster mitigation cum preparedness plan be put in place.

Importantly, it is also underlined that the involvement of local authorities and public will be vital in minimizing further threats and in coming up with local solutions. Also recommended is the creation of watch-posts or police posts at suitable places for timely rescue in road sections falling in high risk zones.

As part of long term measures, a detailed investigation of high risk zones is proposed with vulnerability of inaccessible areas to be accessed by remote sensing and high resolution aerial photographs. The investigation of these areas should be completed in advance to facilitate preparation of disaster mitigation plans ahead of the ensuing monsoon.

The Mines and Geology department has just concluded its preliminary assessment of the earthquake affected areas in the state and submitted its report to the government. A copy of the report has been accessed by NOW! The report, though preliminary and involving only accessible areas, consists of an area wise assessment of locations in the State which were affected by the earthquake of 18 September. Accordingly, some of the affected areas and slopes examined and which have been found to be posing a threat have been highlighted as areas needing urgent attention.
The areas falling between Chungthang and Lachung have been found to be among the worst affected, especially the river bank slopes; besides the landmass has also been found to have developed cracks and fissures here. The area between Lema and Lempokhari experienced the worst situation and a large chunk of landmass was washed away by a flash flood which was found to be even greater than the impact caused due to glacial lake out-bursts flood of the previous century. What is of particular concern, as per the report, is the formation of near vertical slope all along the river bank and formation of cracks on the landmass. In this context the report highlights Lema, Lephkha & Bop areas as needing urgent attention.
It was also studied that the rocks here are brittle and susceptible to weathering and jointly forming geologically vulnerable zones with the recent earthquake having led to further aggravating the degradation. The report further states that “…the area being under frost and thaw environment, the chances of rock bursts at higher elevation is high”. This area needs to be further examined in detail.
The major damages at Lachung area were found to have caused due to earthquake induced flash flood with obstruction of streams by the debris from hill slope resulting in landslide in the area. “There is also apprehension of the threat of glacial lake outbursts. The glacial lakes need to be monitored on regular basis to assess the threat,” states the report.
Lachen was found to have remained comparatively safe except for the development of minor cracks on buildings; besides the Chungthang-Lachen section was also found to be subjected to development of instable zones threatening vehicular movement.
There was also a massive landslide between Lachen and Zemu; however the report states that the exact position of future threat is not known at present and that the area needs to be investigated to assess the future threat. The same goes for areas beyond Zema which also reported severe damages.
Upper Dzongu area was among the worst affected by the earthquake with villages there having taken substantial damage and many killed. Here, the report states that the rocks being brittle in nature and there is apprehension that the vulnerable zones have developed which pose threat to life and property of local people in future. However as far as slides are concerned, as most slides were found to have occurred in inhabitable areas any instability due to degradation should not have future impact on life and property, the report states.
For Lower Lingza too, it is reported that landslide and slope failure have not been noticed within the visible zones the formation of unstable landmass and rocks cannot be ruled out and the area needed further investigation.

Comment by Praful Rao
It is coincidental that this statement by Dept of Mines, Govt of Sikkim comes just days after our Workshop on "Hazards and Critical Environmental Issues of Darjeeling-Sikkim Himalaya" on 23Nov2011, where my talk on "5 Months to go for the next monsoons" emphasized on the very same points made above.