Glacier Lakes: Growing danger in the Himalayas.

The Guardian published an article on 11 October 2001 entitled “Deadlier by the day. The Himalayan lakes that are threatening a disaster.” This article is about the hazard of Glacial Lake Outburst Floods (GLOFs), and the increased hazard with more glacier front lakes developing as glaciers retreat due to climate warming. The article PLUS A VIDEO ON THIS TOPIC can be reached via the link above, or via: http://www.guardian.co.uk/environment/2011/oct/10/glacier-lakes-melt-himalayas?newsfeed=true
An example given in the article is Glacial Lake Imja which did not exist in 1953 when Everest was first climbed. In 1992 the lake was about 1.3km long ( see http://iahs.info/redbooks/a218/iahs_218_0319.pdf ) Teije Watanabe has been studying this lake since the 1990s and returned in September this year and found the lake much larger (about 2.4km long). Like many of these ice front glacier lakes, this lake is dammed by moraine deposited by the glacier as it retreated. Some moraine barriers are even more hazardous because they are ice cored (ice buried in glacial sediment), and the moraine may subside as the ice melts. Now there is a risk of the moraine barrier on Lake Imja being eroded by a meltwater flood (possibly aided by collapse of buried ice, if present). This could release the large volume of water held behind the moraine barrier and a mega flood would surge down the valley destroying villages, drowning people, damaging agricultural land etc. There are a range of possible counter measures: reducing lake volume by siphoning water or by diversion tunnels , strengthening the natural spillway over the moraine dam, etc. However the remote location of many of these glacial lakes makes all engineering work difficult and more expensive.
John Reynolds, a British engineering geologist with much experience of this topic, cautions that Lake Imja is not the most hazardous, but it has had more attention because it is close to the main route to Mount Everest. There are many potentially hazardous glacial lakes. He advises that a Himalaya wide evaluation of GLOF risk is needed and an action plan needs to be drawn up to tackle this hazard in the Himalaya on an international scale.

Large Coastal Rockfall caught on Video.

Large Coastal Rockfall caught on Video.
A video of a large rockfall at North Cliffs, Cornwall, England, has been recorded due to quick thinking of someone on the spot. This has been reported with some useful comment in The Guardian of 7 October 2011 at:
http://www.guardian.co.uk/science/2011/oct/07/massive-cornwall-rockfall-on-video
This is an exceptional opportunity to see a natural rockfall. It is estimated that about 100,000 tonnes of rock fell. This is an extremely unusual video as it is very unlikely someone is at a suitable place with a camcorder ready at the right time. The 50 second video shows a rockfall which converts a 100m high rock cliff to a debris slope. A second video shows the same site 2 weeks later when the lower portion of the debris slope has been eroded by the sea, and conversion to a new, more complex, coastal slope form is underway.
These videos were originally placed on You Tube and if the link above doesn’t go to both videos, you can see them by opening You Tube and searching “Massive Cornwall Rockfall” and “North Cliffs Failure (2 weeks later)”.

Sinkhole appears after storm

A large sinkhole, some 70m deep, has appeared in the ground, swallowing two buildings, during a heavy storm in Guatemala City. Following more than 1000mm of rainfall in a single storm event, many instances of flooding and local landslides were also reported. It is likely that the sinkhole, formed from dissolution of limestone over thousands of years, was infilled with sediment which was washed away as a result of the storm. The link above goes to a clip of the sinkhole on the BBC web site.
The image is from http://www.blindloop.com/wp-content/uploads/2010/04/Sinkhole.jpg. There are some other spectacular images at http://tinyurl.com/2942est.

Hazardous landslide lake

In the Hunza Valley, Pakistan, a large landslide on 4th January this year blocked the valley, with the potential to produce a very large and hazardous lake. The initial landslide killed 19 and displaced 250 families. Since then attempts have been made to construct spillways to limit the volume of the lake, which is now about 20km long and 100m deep in places. 25,000 people have been evacuated by boat from the upper valley. The lake volume increased slowly in the winter, but in May, with the onset of summer and much melt water, the lake has increased rapidly in volume. Evacuation of 18 villages to 30m above river level is underway and warning sirens installed to aid last minute evacuation. The situation is extremely hazardous as the lake may now overflow within days. The exact size of the possible flood is obviously unknown but some estimate that it may exceed the 30m planned evacuation level. A web search for "Hunza Valley Landslide" gives a large amount of extra information.

Ice avalanche produces a “tsunami” in Peru

On Tuesday 13 April Rory McCarroll, Guardian Latin America correspondant, wrote an article entitled "Peruvian glacier split triggers deadly tsunami". A mass of ice 500m by 200m split of the Hualcan Glacier and dropped into a lake, "triggering a tsunami that breached 23m high levees". 50 homes and an important water processing plant were destroyed and at least one person was killed. Settlements in the valley were evacuated because there was risk of further ice avalanches. The town of Carhuaz, population 25,000 (Reynolds, 1992) and nearby settlements were affected. Carhuaz has been threatened by glacial flooding hazards in the past (Reynolds, 1998). Further outburst floods and related are likely as the glaciers in this region retreat under the influence of global warming.

Reynolds J.M. 1992. The identification and mitigation of glacier-related hazards: examples from the Cordillera Blanca, Peru. In McCall G.J.H., Laming D.J.C. & Scott S.C. (eds) Geohazards. Chapman & Hall, London 143-157.
Reynolds J.M., Dolecki A. & Portocarrero C. 1998. Construction of a drainage tunnel as part of a glacial lake hazard mitigation at Hualcan, Cordillera Blanca, Peru. In Maund J.G. & Eddleston M. (eds) Geohazards and Engineering Geology. Geological Society, London, Engineering geology Special Publications, 15, 41-48

Remote sensing of disasters

SciDev Net asks the question; satellite remote sensing data can provide crucial information for managing natural disasters. How can developing countries access and make use of these data? And what must policymakers do to prepare? Click on the link above to explore some of the facts and figures relating to the use of remote sensing for disaster management. There are also discussions about the lack of political support in some developing countries, case studies of where remote sensing has been used to good effect (including forest fires, drought and volcanic activity), and issues around improved education for hazard monitoring.

2008 - the year of the disaster

An international insurance company, Munich Re, has said that 2008 has been one of the worst years for natural disasters. A string of floods, tsunami, earthquakes and hurricanes has led to £137bn in financial losses and more than 220,000 deaths. It is thought that climate change has led to an exacerbation of certain hazards, particularly flooding and weather-related events such as hurricanes. The worst single events of the year have been the Chinese earthquake that left 70,000 dead and the Burmese cyclone Nargis that killed 130,000.

Jurassic Coast Landslide

On 6th May 2008, 95m high cliffs along a 400m wide section of World Heritage Coast between Lyme Regis and Charmouth collapsed. This stretch of coast is no stranger to landsliding and comprises a similar range of weak shales and marls as much of the Isle of Wight, also subject to frequent landslide activity. Long term inundation from prolonged summer and winter rainfall produces high pore water pressures that contribute to instability and such events can be expected to become more frequent with more the extreme weather associated with climate change. Video footage of the slide can be seen at the BBC web site http://news.bbc.co.uk/1/hi/uk/7388564.stm and a Google Earth image of the coast affected is available at http://tinyurl.com/69hn2b.

Snakes Pass Landslide

The A57 Snakes Pass road (the main link between Manchester and Sheffield) has been closed for two weeks due to a landslide (image from Prof. Brian Whalley). The landslide occurred following heavy rain, a sequence of events not unusual in this locality (e.g. http://tinyurl.com/23gmww). The steep hillslopes in this region of the 'Dark Peak' are particularly vulnerable to mass movement being underlain by thin sandstones interbedded with weak, easily weathered shales. Other notable landslides in the immediate vicinity include Alport Castles (see http://tinyurl.com/2snvl2) and Mam Tor (see http://tinyurl.com/38fkq2) - (image from DTN).

Flooding in Australia

For news of recent inland and coastal flooding in eastern Australia click on the link in the title above. For some video aerial footage visit http://tinyurl.com/3cvc63. Flash flooding has occurred in some parts. Ironically, the spate of heavy rainfall leading to this flooding follows months of severe drought.

Tsho Rolpa outburst threatened

The Tsho Rolpa glacial lake in the high Nepalese Himalayas, has been carefully monitored for a number of years. The lake is constrained by a moraine dam which is vulnerable to ground movements (from landslides, glacier falls and seismic activity) and from melting of ice blocks contained within it. The glacial outburst flood that could potentially result from a breach of the moraine dam would reach villages as far as 100km downvalley. Subsequent water shortages would have severe effects on the Ganges as well as Nepal. The glacier which feeds Tsho Rolpa has receded rapidly over the last 10 years - a function of global warming - and the lake grows in length by 100m each year. Controlled lake drainage via an artificial outlet channel ensures that water levels are gradually being reduced, but not at a sufficient rate to reduce pressure on the moraine. Nepal has 17 similar glacial lakes which have no control measures in place. Further information can be found at: http://tinyurl.com/ytkkpm. The image shows a small ice-marginal lake at Hoffelsjokull in Iceland.

Flooding in Mexico

Prolonged and heavy rainstorms over more than a week have caused seven rivers in the Mexican state of Tabasco to swell, flooding 70% of the land area of this Gulf coast state. It is thought that 100% of crops will be lost. Estimates vary as to the number of fatalities so far, but numbers are small. At the onset of the storms last week, 23 died in an oil rig collision. The state was similarly affected, though not as severly, by unprecendented rainfall in the summer of 1999 (further details at http://www.fas.usda.gov/pecad2/highlights/99-10/fsa101499.htm).

The image is copyright of BBC News.

Calving glacier hazard

Holidaymakers aboard a cruise ship, sailing off Svalbard, were injured when calving ice from the Horn Glacier crashed onto the side and deck of the ship. It would appear that most injuries were caused due to the ship listing due to the ice collapse. It is unusual for the calving of glacier ice to result in direct risk to humans in this way but direct risk to tourists occurred at the Miage Glacier in the Italian Alps in 1996 (Tinti et al 1996).

Further reading:
TINTI S., MARAMAI A. and CERUTTI A. V. 1999. The Miage Glacier in the Valley of Aosta (Western Alps, Italy) and the extraordinary detachment which occurred on August 9, 1996. Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 24 (2), 157-161.
REYNOLDS, J. M. 1992. The identification and mitigation of glacier-related hazards: examples from the Cordillera Blanca, Peru. Chapter 13 In: G. J. H. McCall, D. J. C. Laming and S. C. Scott (eds). Geohazards: Natural and Man-made. Chapman and Hall, London, 143-157.

More flash floods and landslides in the UK

Today has seen yet further incidents of flash flooding and associated chaos in the UK, including a landslide at the side of a motorway. BBC News report here: http://news.bbc.co.uk/1/hi/uk/6907316.stm BBC video clip here: http://tinyurl.com/2u33qq

Cataclysmic flood creates new island

A study by Sanjeev Gupta and Jenny Collier of Imperial College has revealed a deep, sub-marine trench through the English Channel which is believed to have been carved out by cataclysmic floods 400,000 years ago. The sub-marine scouring, identified on sonar images, is thought to have occurred due to overflow of a massive ice-dammed lake in the southern North Sea. It is estimated that the discharge was between 200,000 and 1 million cubic metres per second - this is at least four times as much as peak flow from the 1996 Icelandic jokulhlaup. Prior to this event Britain was connected to the European mainland via a land promontory.

Flash flooding in England

Late yesterday evening (Tuesday 19th June) saw flash flooding in many areas of south west and central England. The photograph (Adam Heskins) shows what 15 minutes of rain did in Portishead. There are many reports of road damage and closures, helicopter rescues, airport closures, loss of power, and flooded homes. The Environment Agency still has 27 rivers and their tributaries on Flood Watch and the Met Office has continued to issue severe weather warnings, notably for Grampian region of Scotland which is expected to receive heavy rainfall throughout Wednesday 20th June. A BBC video can be found at: http://www.tiny.cc/flashflood

Columbian floods and landslides

Several villages in Columbia have been hit by flooding and landslides as a result of heavy rainfall. Floods have destroyed a number of homes. Flooding is exacerbated by sediment accumulation in rivers causing narrowing of the channel. Localised rain-induced mudslides have also left around 8 people, mainly children, dead.

Every year dozens of lives are lost as a direct result of the heavy annual rainfall. The poor, living in makeshift accommodation on steep hillslides, are most at risk.

Karst collapse in Borneo

A large sinkhole collapse in Sarawak, on the Malaysian island of Borneo, almost led to the loss of c.100 lives. A traditional longhouse, occupied by around 100 people, was quickly evacuated after a man, taking a late night trip to the toilet, raised the alarm when he felt the earth move beneath him and saw the end of the longhouse sinking into the ground.

For further information on the geology and karst landforms of the Sarawak region, visit http://www.oucc.org.uk/procs/proc11/borneo_karst.htm.

For further information on sinkholes, how they develop and why they collapse, visit http://www.dyetracing.com/karst/karst.html.

New Zealand lahar

On 18th March 2007, a lahar (volcanic mud flow) spilled down Mount Ruapehu in New Zealand. After an eruption of the volcano in 1995, a 40m high wall of tephra had built up around the crater rim. In this latest event the wall was breached, allowing a mixture of acidic rock fragments, volcanic ash (tephra) and water to spill down the flanks of the mountain. Although there was reported to be no loss of life and no significant damage as a result of the lahar, the potential for extremely hazardous events still exists. This is demonstrated by a 1953 lahar from the same volacno which killed 151 people. The image is from NZPA/Stephen Barker/Associated Press.

For a video clip of the event go to the BBC link: Volcano spews rivers of mud

Indonesian mudflow update