Aftershocks from Sichuan earthquake pose threat of secondary disasters
South China Morning Post, 22 April 2013
By Stephen Chen
Secondary disasters such as mudslides and dam-related crises may occur
in the days or even months after Saturday's earthquake, threatening the
safety of residents and rescuers, geologists warn.
Fan Xiao, chief engineer at the Sichuan Geology and Mineral Bureau in
Chengdu, said yesterday the banks along the Qingyi River, in one of the
most geologically unstable regions of the province, had taken a big hit.
Known for its high mountains and deep valleys, the area was already
unstable before the earthquake, with villages and roads sitting almost
in the path of potential landslides, Fan said. And shockwaves from the
earthquake could profoundly increase structural instability in the region.
"Residents and rescuers must be highly alert to the dangers of
mudslides, especially after rain," he said. "There will be lots of rain
in the coming months."
Like all major rivers in Sichuan, the Qingyi has been heavily dammed by
hydropower projects. Though none collapsed during the quake, the biggest
threat to the dams' structural integrity will come during the summer
flood season, Fan said.
Yang Yong , an independent geologist based in Chengdu who is familiar
with hydropower projects in the region, told The Beijing News that he
was worried because of the large number of dams in the quake zone.
"The closest dam was just 10 kilometres from the epicentre," he was
quoted as saying. "Communications and transportation were both cut off.
We don't know the situation there."
The Ministry of Water Resources said on its website yesterday that 14
large dams affected by the shockwaves remained stable, but two
medium-sized dams were damaged. Authorities did not give the extent of
the damage, or the locations or names of the dams. Additionally, 52
small dams were damaged, and states of emergency were issued for five of
them, resulting in downstream residents being evacuated.
More than 3,000 hydropower engineers, workers and military personnel had
been sent to examine all dams in the region and carry out repairs, it said.
The Ministry of Land and Resources said more than 10 landslides had
occurred on roads deemed critical to search-and-rescue work, while
monitors at five possible mudslide sites in Yaan city sounded alerts.
The ministry issued a red alert for mudslides and landslides in towns in
The China Meteorological Administration warned that rain was expected in
the quake zone in the three days following the earthquake, increasing
the risk of secondary disasters.
Sichuan is also known for its nuclear facilities, many of which are for
military purposes. The China National Nuclear Power Corporation
announced on its website that its nine nuclear facilities in Sichuan
experienced various levels of shockwaves at the weekend, prompting
safety checks. There had been no reports of leaking pipes or collapsed
buildings at the facilities.
As of 6pm yesterday, the quake zone had experienced 1,642 aftershocks -
the strongest with a magnitude of 5.4.
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