The environment in the news thursday, 19 August, 2010
BBC: Smos satellite tracks Pakistan floods
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- BBC: Mass rescue after landslide hits China village
- BBC: Earthquake ‘double whammy’ caused 2009 Tonga tsunami
BBC: Smos satellite tracks Pakistan floods17 August 2010 Europe's "water satellite" has provided a different perspective on the floods in Pakistan. The Smos spacecraft senses the wetness of soils, and its unique instrument has detailed how the earth became saturated in the monsoon rains. The floods, which began more than two weeks ago in the mountainous northwest, are the worst in recorded history. Some 20 million people and 160,000 sq km of land - a fifth of the country - have been affected by the disaster. Data from the European Space Agency's new Smos satellite has been processed to make a series of maps. The four snapshots featured at the top of this page run from 17 July to 4 August. They show the ground getting progressively wetter, indicated by the shift from warmer (yellow/orange) to cooler (blue/grey) colours. The consistent blue in the south reflects the naturally wetter landscape that surrounds the Indus River where it enters the Arabian Sea. Smos is a scientific satellite that is pioneering a novel Earth observation technique. It carries an 8m-wide interferometric radiometer that senses the natural emission of microwaves coming up off the planet's surface. Variations in the sogginess of the soil will modify this signal. Satellite data is frequently used in the relief response to major disasters, and in the case of Pakistan the world's satellite fleets were mobilised on 2 August to provide space-borne information under the International Charter [on] Space and Disasters. The charter was activated by US Office of Foreign Disaster Assistance. Radar data, in particular, is used to identify the presence and extent of floodwater. But there is an expectation that once the Smos observation technique has become sufficiently mature, it too will be able to play a leading role in disaster mitigation. By identifying the soils closest to saturation, the satellite would provide advance warning on which areas in a flood-stricken region were likely to flood next if weather conditions failed to improve and rains continued to fall. Dr Claire Gruhier is a Smos researcher from Cesbio in Toulouse, France. She told BBC News the results were preliminary: "What we show is not the flood area; what we show is the water content in the soil. So, it is not exactly the same information. But our maps are very consistent with the flood-affected areas in Pakistan revealed by other satellites." Smos carries an 8m-wide, three-armed interferometric radiometer Smos principal investigator, Dr Yann Kerr, added: "I am quite confident that in a few months when the calibration and validation is [completed on Smos] and the algorithms are fine tuned, we will be able to infer also the extent of the actual floods. Smos is less accurate than optical/radar sensors, no question; but it is all-weather and sees any point of the globe in less than two days." The Smos team is particularly encouraged to have got good results out of a mountainous area, a type of terrain from which it is harder to retrieve soil moisture values from space. The Smos satellite was launched in November last year, since when it has been going through a commissioning phase. Fully processed data products are due to be released to the world's scientific community next month. As well as studying soil moisture, the spacecraft's instrument can also sense changes in salinity in ocean water. The radiometer's three-armed arrangement has earned Smos the nickname of the "space chopper" because of its resemblance to the rotors of a helicopter. Back to Menu _________________________________________________________________ BBC: Mass rescue after landslide hits China village18 August 2010 Most of the 67 people missing after a landslide in south-western China have been rescued, reports say. Residents of Puladi, in Yunnan province, were trapped in their homes by the rushing mud as they slept. Unusually severe summer rains have triggered mudslides and floods that have killed more than 1,500 people across China in recent months. About 470 people are still missing in Zhouqu county, Gansu province, after a landslide enveloped the town recently. More than 1,200 people have been confirmed dead after the disaster hit on 8 August. More than 305 million people across China have been affected, with damage totalling $1.7bn (£1.1bn), according to state media. Swollen river Roads, power lines and telecoms have been cut to Puladi, a mountainous area that borders Burma. The Chinese news agency Xinhua reported that mudslides also destroyed a bridge and swelled the Nujiang river. It quoted the Yunnan Provincial Emergency Response Office saying the river level had risen by 6m (20ft). It cited sources as saying that Litoudi Village, about 10km from Puladi, was also badly hit by mudslides. Last month, workers in Puladi building a hydro-electric power station were hit by a landslide. Eleven people died. The National Meteorological Centre said the chance of more landslides was "relatively large".
18 August 2010 A strange double earthquake was responsible for the tsunami that devastated parts of the South Pacific in 2009, scientists claim. In a rare set of events, an initial 8.1 magnitude earthquake was immediately followed by a second 8.0 shock. The resulting tsunami devastated the South Pacific islands of Tonga and Samoa. An estimated 192 people died as four waves each more than five metres high surged inland. And international team led by Professor Thorne Lay of the University of California, US, studied the causes of the tsunami. The results are published in the journal Nature. Record shock The earthquake was unusual, not only because of the double shock, but also because of the location of the first event. Almost all great earthquakes - shocks of magnitude 8.0 or bigger - occur at locations where fragments of the Earth's rigid crust, known as tectonic plates, grind against one another. However, the initial Tonga earthquake occurred up to 100 km (62 miles) from the closest tectonic plate boundary. As such it is the largest ever earthquake of this type reported in more than 100 years of monitoring. A radio DJ describes the moment the tsunami hit American Samoa in 2009 Professor Lay commented that the Tonga earthquake was "unlike anything seismologists have seen before". This "out of place" earthquake was triggered as part of the Earth's crust was dragged under another piece of crust. As it bent, it snapped near its middle sending out shockwaves. Earthquakes and tsunamis are a common feature of the Pacific. The region - known as the Ring of Fire because of its many volcanoes - is one of the most geologically active parts in the world In 2004, a massive 9.1 magnitude earthquake triggered the infamous Boxing Day Tsunami. This catastrophic event killed nearly a quarter of million in 14 countries throughout the Pacific and Indian oceans. Back to Menu _________________________________________________________________ Directory: cpi -> briefs briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news briefs -> The environment in the news Download 231.95 Kb. Share with your friends:
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