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

Tropical glacier disappearing

The Quelccaya ice cap is the largest ice sheet in the tropics and one if its outlet glacers, the Qori Kalis glacier, is fast shrinking due to global warming and the effects of El Nino. There are fears this Peruvian glacier could disappear within just five years as its current retreat rate is 60m yr^-1. The report comes from work conducted by climate scientist, Professor Lonnie Thompson, from Ohio State Univeristy. The image is copied from the BBC web site (link above).

Shifting shores: Adaptation is the answer

The National Trust have published a report 'Shifting Shores' on the effects of coastal flooding and erosion over the next century. The study, conducted by Halcrow, predicts that over 4,000 hectares of Trust land will be at risk of flooding and more than 600km will be subject to erosion. The causes of the predicted flooding and erosion include climate change (especially high tides and severe storms), the ongoing dynamic nature of coastal environments and isostatic rebound. The Trust pledges to take the long term view and adopt a plicy of adaptation rather than defence. This means adapting infrastructure and careful planning for recreation, heritage and wildlife. The full report can be downloaded at: http://www.nationaltrust.org.uk/main/w-shifting_shores.pdf

Glaciers shrinking faster

The BBC reports on new data available from the World Glacier Monitoring Service (http://www.wgms.ch/) which suggest that the rate of glacier shrinking due to global warming is now three times as fast as it was in the 1980's. The photo (from O. Gruber, H. Rentsch and M. Siebers from the Bavarian Academy of Sciences and Humanities) was taken in 1968 at Vernagtferner in Austria. Photos taken at the same location in 1912 and 2003 are shown in the BBC News item and demonstrate the huge shrinkage that has occurred over the last century. During 2005 alone, the glacier was reduced in thickness by more than 0.5m.

Indonesian mud volcano continues to erupt

Remember the unstoppable 'mud volcano' in East Java (see posting on 5th October 2006)? A new report into the disaster has been produced by a consortium of Durham, Cardiff and Aberdeen Universities and GeoPressure Technology Ltd, headed by Professor Richard Davies of Durham University’s Centre for Research into Earth Energy Systems (CeREES). They conclude that the flow is almost certainly the result of drilling. When drilling, boreholes are usually protected by steel casing to prevent collapse of the walls due to gas or fluid pressure. It appears that casing was not used during this exploratory drilling into an artesian limestone aquifer. The rock walls fractured, allowing a mud-water fluid mixture to rise to the surface. Poor drilling practice is cited as the most likely cause of the 'eruption'. The team have rejected antecedent earthquake activity as being a contributing factor. Having studied satellite imagery of the area, they also predict that ultimately, the central vent will collapse, forming a crater. There is further information and images in the BBC News report: http://news.bbc.co.uk/1/hi/world/asia-pacific/6293757.stm.

Satellite images of Philippine mudslides

NASA satellite images taken on 12th December provide impressive visual evidence of the impact of ongoing ash and lava flows from Mayon Volcano in the Philippines. On November 30th, a torrential rainstorm turned the loose ash, which has been accumulating since July, into a series of mudslides. The mud reached the outskirts of Legazpi on the south and west volcano flanks and 1000 people are believed to have lost their lives. The images can be viewed via the link above. Click HERE for further information on NASA's Terra satellite. The disaster was originally reported by CNN. Image (Mayon Volcano) from http://www.arrakeen.ch/phil2/philippinesdec2000.html.

Floodline: Flooding in the UK

At this time when there are a number of severe flood warnings in the UK, it is useful to be reminded of the Floodline service provided by the Environment Agency (click link above for their web site). Floodline provides information on flood risk in your area (using an interactive map) and explains ways in which you can defend your property against flooding. The web site also gives current flood warnings and boasts an extensive library of publications relating to flooding and flood management. An excellent site for students of geomorphic hazards!

99.9% of glaciers shrinking

Dr Georg Kaser (University of Innsbruck), President of the IUGG Commission for the Cryospheric Sciences and one of the lead authors of the IPCC 4th Assessment Report, and his team, have published the results of a global survey of glacier mass balance (Article: Kaser, G., Cogley, J. G., Dyurgerov, M. B., Meier, M. F. and Ohmura, A. 2006. Mass balance of glaciers and ice caps: Consensus estimates for 1961–2004, Geophysical Research Letters 33, L19501). The team concludes that there has been a sharp acceleration in the rate of glacier melting in the last five years and they attribute this directly to global warming. Worldwide glacier melting is likely to lead to substantial losses to water suplies for major areas of South America and Asia.

Exploratory drilling triggers unstoppable mudflow....

A team of geologists from the University of Oslo has stated that efforts to stop the mud flowing 200m from a 2km deep exploratory borehole in East Java are "unlikely to succeed". The mud started gushing from the hole on May 29th and is continuing at a rate of 50,000m³ per day. Two villages have already been flooded and another four will probably have to be destroyed. There are suggestions that the resulting environmental devastation could reach the catastrophic proportions of the Exxon Valdez sunken oil tanker disaster in 1989, Alaska. The geological team have suggested four possible fundamental causes for the mudflow; gas-rich fluid breaching coral mounds on top of the limestone rock; gas produced from a magmatic reaction; a new mud volcano; or migration of hydrothermal fluids from nearby.

Eiger rockfall awaited

Geologists monitoring Mt. Eiger in the Swiss Alps have reported that a major fissure is opening up at the rate of 75cm per day, loosening a block of rock 2x10⁶ m³ in size. If the rockfall occurs (it is expected in the next few days), debris settling onto glaciers below could block streams and cause downstream flooding or affect water supplies, but there is no direct danger to Man or property. The report made to The Guardian blames global warming for this activity but no evidence for this is presented. It is much more likely to be part of the natural cycle of erosion and deposition occurring in the mountains.

Global glacier mass balance in decline

The World Glacier Monitoring Service (WGMS) based in Zurich collects and provides annual mass balance data for glaciers around the world. These data, reported by the WGMS at the recent European Geosciences Union meeting in Vienna, demonstrate a mean loss of 2.9% per decade from 1850 to 1970. This figure has increased to 8.2% for the period 1970 to 2000. Further information is available from the WGMS web site (from which mass balance data are available) and a recent BBC News report.

The image shows Nigardsbreen on the Jostedals ice cap in central Norway. This is one of the few glaciers which is currently advancing, against the gloabal trend....

Severe land degradation in Africa

A new report by The International Center for Soil Fertility and Agricultural Development (IFDC) presents findings of a programme of monitoring soil 'health' in Africa over the period 1980 to 2004. The IFDC concludes that in several countries the use of the land for agriculture is unsustainable because of nutrient depletion. This has arisen due to over-exploitation, use of marginal land and poor land management practices. The situation is exacerbated by the low usage of fertiliser in Africa which has one of the lowest rates of usage in the world.

Rain-induced landslide

Major mudslides have occurred in the Philippines, effectively submerging a village under thick mud. The death toll is still being assessed, but latest reports from the Philippine Red Cross, suggest that at least 200 people have lost their lives and as many as 2,000 are still missing. The landslides have occurred in Leyte Province, following torrential rain and flash flooding. However, while rainfall may have been the main CAUSE of the landslides, the TRIGGER may have been provided by a small earthquake according to Rene Solidum (Director of the Institute of Volcanology and Seismology in Manila). Other potential causes include logging (see report from New York Times).

Landslide in Dorset

On 14th January 2006 a landslide occurred near Charmouth in West Dorset and 17 people had to be rescued from rising tides due to the landslide debris. The landslide has destroyed more of the coastal path and new cracks have opened up in the fields above, indicating further activity is to come. The area is prone to landsliding because impermeable Jurassic clays and limestones underly permeable Cretaceous Greensand. Following prolonged rainfall, the accumulation of percolated water at the boundary between the two formations causes seepage, lubrication and a consequent loss of friction. The result is that the upper strata slide over the underlying strata.

For more information on the geology and landsliding along this stretch of coast, visit the Jurassic Coast web site

World's tallest building triggers earthquake?

The world's tallest building, Taipei 101, situated in Tawain, is being blamed for the increased number and magnitude of earthquake tremors that have occurred beneath it. The building, situated on soft sedimentary rocks, is 508m tall and exerts 0.5Mpa on the ground. It has been argued that these stresses are transferred 10km down to the upper crust and have re-activated an ancient fault. Although the number and magnitude of earthquake tremors have increased since construction commenced, some argue that this could simple reflect short-term variability in the natural cycle of events. Others also argue that stresses cannot be transferred to such a depth below the Earth's surface. Furthermore, the total load applied to the ground by Taipei 101 is negligible compared to some stuructures such as dams. What do YOU think?

Natural disasters producing environmental refugees

According to the United Nations University, there are likely to be 50 million worldwide environmental refugees by 2010. The main sources of refugees are land degradation due to unsustainable land management; and flooding, exacerbated by global warming. The UNU have calculated that the number of refugees created by natural disasters exceeds that produced by war and conflict. The problems are likely to increase as environmental refugees join poor, squatter communities in urban areas.