Flooding in Southeast Asia 2011 : 2554 มหาอุทกภัยแห่งเอเชียตะวันออกเฉียงใต้

Thailand and Cambodia continued to cope with widespread flooding at the beginning of November 2011. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured the top image on November 1, 2011. For comparison, the bottom image shows the same area three years earlier, on November 12, 2008.

These images use a combination of visible and infrared light to better distinguish between water and land. Water ranges in color from electric blue to navy. Vegetation is green. Bare ground and urban areas are earth-toned. Clouds are pale blue-green.

Barely discernible in 2008, Thailand’s Chao Phraya River and its tributaries have spilled onto floodplains in 2011. Meanwhile, in neighboring Cambodia, Tônlé Sab (Tonle Sap) and the Mekong River have soaked normally dry land. Rivers are also visibly swollen in eastern Thailand.

Flooding plagued much of Southeast Asia in the 2011 monsoon season. Thailand, Cambodia, Burma (Myanmar), Vietnam, Laos, and the Philippines—which experienced heavy rainfall from intense tropical storms—suffered a collective death toll of more than 1,000, according to The Diplomat. More than 400 people had drowned in Thailand, and 250 people had perished in Cambodia. Besides the human toll, the floods swamped agricultural land. The United Nations warned that the inundated fields raised the possibility of food shortages.

By November 1, Voice of America reported, many communities in Thailand had spent weeks under a meter (3 feet) or more of water, and floods had affected two-thirds of the country’s provinces. The threat of floods in Bangkok was growing. At the beginning of November, Bangkok Post reported, all 50 districts of the capital city were at risk of flooding. The Chao Phraya River flows through the city to the Gulf of Thailand, but high tides from the sea had pushed water up the river for three days, just when high water from floods threatened to overwhelm city canals.

Across the border, flood waters had transformed northeastern Cambodia into “a vast inland sea,” The Guardian reported. Stagnant water, and residents forced to live in close quarters with livestock, contributed to the disease toll. Dengue fever was on the rise, and doctors had diagnosed the first cases of cholera.


  1. Bangkok Post. (2011, November 1). All districts in Bangkok still “at risk.” Accessed November 1, 2011.
  2. Corben, R. (2011, November 1). As floods drag on in Thailand, displaced grow restless. Voice of America News. Accessed November 1, 2011.
  3. Hunt, L. (2011, November 2 [local time]). Asia counts flood costs. The Diplomat. Accessed November 1, 2011.
  4. Tran, M. (2011, November 1). Cambodia floods bring mounting disease toll. The Guardian. Accessed November 1, 2011.

NASA images courtesy MODIS Rapid Response Team, Goddard Space Flight Center. Caption by Michon Scott.

Instrument: Terra – MODIS

Magnitude 6.3 Earthquake near Christchurch, New Zealand

At 12:51 p.m. local time on February 22, 2011 (11:51 p.m. February 21 UTC), a 6.3-magnitude earthquake struck the South Island of New Zealand, the U.S. Geological Survey (USGS) reported. Several smaller aftershocks followed. The quake occurred near the city of Christchurch, a community of some 400,000 residents on the east coast. The initial death toll was 65, according to news reports, and authorities warned that the toll could rise sharply as search-and-rescue efforts continued.

This map shows the earthquakes that occurred near Christchurch since September 3, 2010. On that day a magnitude 7.1 quake struck to the west of Christchurch. Black circles represent earthquakes from September 3, 2010, until February 21, 2011. Red circles show the locations of the magnitude 6.3 quake and aftershocks on February 22 and the morning of February 23. Larger circles represent stronger earthquakes. Yellow shows urban areas, including Christchurch.

The USGS characterized the 6.3-magnitude quake on February 22 as an aftershock of the quake that struck to the west, in Darfield, New Zealand, on September 3, 2010. Darfield lies about 50 kilometers (30 miles) west-northwest of Christchurch. Although no specific tectonic structure linked the two events, numerous aftershocks of the September quake occurred along a roughly east-west line, as this image indicates. The USGS stated that the quakes were associated with regional tectonic plate boundary deformation. The Pacific Plate and the Australia Plate interact under the South Island of New Zealand.

The Darfield earthquake in September 2010 caused no casualties, even though it had a higher magnitude. Besides striking closer to a major population center, the6.3-magnitude Christchurch earthquake had a depth of just 5 kilometers (3 miles). The New Zealand Herald reported that, whereas the Darfield quake happened in the early morning hours, the February 22 quake struck at the “worst possible time” of day—at the lunch hour when city streets were crowded with shoppers, diners, office workers, and school children. Moreover, some of the buildings that collapsed may have been weakened by the September 2010 quake.

Effects of the Christchurch earthquake were felt some 200 kilometers (125 miles) away, along the South Island’s west coast. A 30 million-tonne (33 million-ton) chunk of ice broke off from the Tasman Glacier, and slid into Tasman Lake. In fact, officials had expected ice would break off the glacier, although they expected the event to result from heavy rainfall caused by La Niña.

Source : http://earthobservatory.nasa.gov