Dams hold danger of floods whenstrong earthquakes hit Himalayas
Prem Kumari Khanal piles corrugated sheets of tin in the destroyed village of Pokharidanda, near the
epicenter of April 25's massive earthquake, in the Gorkha District of Nepal, May 2, 2015. Photo: AP Photo/
Wally Santana
Earthquakes can create massive amounts of damage. The people of Nepal, a
nation of 27 million located in the Himalayan mountain range south of China,
know this all too well. Earlier this year, two massive earthquakes struck in the
Himalayas, killing more than 8,500 people.
The people of Nepal are still recovering. Scientists, meanwhile, are already
worrying about the next earthquakes that will strike the region. One growing
concern has to do with the dams in the Himalayas. More than 600 large dams
have been built or are in some stage of construction or planning in the
By Scientific American, adapted by Newsela staff on 09.10.15
Word Count 830
mountains. Scientists are worried that a large earthquake could cause some of
the dams in the Himalayas to burst. A burst dam would release a sudden flood
of water, posing a grave threat to local communities.
Nepal Quakes Caused Damage
The 2015 earthquakes that hit Nepal cracked or damaged several dams. The
next earthquake could be even stronger. According to a number of engineers
and scientists, many of the dams in the Himalayas are probably not strong
enough to withstand the worst earthquakes that could hit the region.
Burst dams would unleash huge quantities of water, which would rush down
through the mountains toward towns and cities. A collapse of Tehri Dam in the
central Himalayas, for instance, would set loose a wall of water about 650 feet
high. The water would hit two towns. The flooding would affect six additional
cities with a combined population of 2 million.
Earthquakes occur in the region because of the movement of layers of rock
miles below the surface. According to the theory of plate tectonics, different
pieces of the earth's crust ("plates") are in slow, steady motion. One plate below
Nepal, the Indian plate, is pushing under the Asian plate. It moves roughly 6 feet
per century, but it regularly gets stuck. This leads to a build-up of pressure.
When the pressure reaches a certain level, the plates become unstuck, causing
an earthquake. The Himalayas are located on a "fault line," an area where two
plates push against each other below the surface. Because of its location in the
Himalayas, Nepal experiences earthquakes.
"Great" Earthquake Seen As Likely
Laurent Bollinger is a seismologist, a scientist who studies earthquakes, at the
French Alternative Energies and Atomic Energy Commission. He has studied
the effects of the earthquakes that hit Nepal earlier this year. According to
Bollinger's research, the earthquakes destabilized the region, making a "great"
earthquake more likely to occur in the future. A "great" earthquake is any
earthquake that scores an 8.0 or higher on the Richter scale. The Richter scale
rates the strength of earthquakes from 0 to 10. The two earthquakes that hit
Nepal in April and May 2015 were measured as 7.8 and 7.3, respectively.
Other studies indicate that these earthquakes released only a fraction of the
pressure that has built up between the plates below the Himalayas. This
suggests that more earthquakes are likely in the coming years. Vinod K. Gaur is
a seismologist at the CSIR Fourth Paradigm Institute in India. He says that there
could be a 8.0 earthquake in the Himalayas in the near future. If there are no
earthquakes for 200 years, the pressure will keep increasing. When an
earthquake finally comes, it will be even more powerful.
Given the likelihood of more earthquakes in Nepal, the dams in the region have
to be specially reinforced. They must be able to withstand the strong ground
shaking of an extreme earthquake, says Martin Wieland of the International
Commission on Large Dams.
India, China Secretive About Dam Designs
Part of the trouble is that scientists are not always allowed to study the dams
freely to determine whether or not they are strong enough. Most of the dams in
the region supply power to India and China. Although every nation has its own
regulations, India and China are secretive about their dam designs. Outsiders
are rarely allowed to examine Indian and Chinese dams.
Scientists who have been able to study dams in the region have sometimes
found cause for concern. Probe International is a Canadian environmental
research organization. It studied China's Three Gorges Dam. It found that the
designers had not considered worst-case scenarios when designing the dam's
earthquake resistance.
Scientists Seek Safer Construction
If the Indian and Chinese governments have not put in place the proper
reinforcements, hundreds of dams could be in danger of bursting when the next
big earthquake hits the Himalayas. If that happens during a rainy season, when
the dams are full, the burst dams could create massive damage.
A handful of scientists have taken the lead in arguing for safer dam
construction. They have only had limited success, though. For now, all they can
do is call attention to the problem.
Scientists hope that, with the help of public pressure, dams in the Himalayas will
be reinforced to withstand great earthquakes. Otherwise, the next great
earthquake in the area may result in a man-made tsunami.
Quiz
1 All of the following are reasons why another earthquake is likely to happen in the
Himalayas EXCEPT:
(A) The Himalayas are over a fault line.
(B) Often when there is a lot of flooding, there are also earthquakes.
(C) Once there is an earthquake, it makes it more likely for another one
because the area becomes unstable.
(D) The scientists have discovered that the last earthquake only
released a small percentage of the pressure from below the Earth's
crust.
2 According to the article, what is the MOST likely reason why the scientists might be
frustrated?
(A) because they do not have a lot of power to convince countries to
build stronger dams
(B) because the earthquakes in Nepal will probably continue
(C) because a tsunami in the Himalayas could cause a lot of damage
and cost lives
(D) because other countries do not build dams as strong as the ones
that Indian and China built
3 Read the following sentence from the introduction [paragraphs 1-2].
A burst dam would release a sudden flood of water, posing a
grave threat to local communities.
Using the word "grave" in the above sentence adds all the following tones to the
sentence EXCEPT:
(A) formal
(B) sarcastic
(C) serious
(D) pessimistic
4 Read the following selection from the article.
Laurent Bollinger is a seismologist, a scientist who studies
earthquakes, at the French Alternative Energies and Atomic
Energy Commission. He has studied the effects of the
earthquakes that hit Nepal earlier this year. According to
Bollinger's research, the earthquakes destabilized the region,
making a "great" earthquake more likely to occur in the future.
What phrase below is the BEST definition for the word "destabilized"?
(A) to bring peace
(B) to upset people
(C) to keep the status quo
(D) to cause unrest
Answer Key
1 All of the following are reasons why another earthquake is likely to happen in the
Himalayas EXCEPT:
(A) The Himalayas are over a fault line.
(B) Often when there is a lot of flooding, there are also
earthquakes.
(C) Once there is an earthquake, it makes it more likely for another one
because the area becomes unstable.
(D) The scientists have discovered that the last earthquake only
released a small percentage of the pressure from below the Earth's
crust.
2 According to the article, what is the MOST likely reason why the scientists might be
frustrated?
(A) because they do not have a lot of power to convince countries
to build stronger dams
(B) because the earthquakes in Nepal will probably continue
(C) because a tsunami in the Himalayas could cause a lot of damage
and cost lives
(D) because other countries do not build dams as strong as the ones
that Indian and China built
3 Read the following sentence from the introduction [paragraphs 1-2].
A burst dam would release a sudden flood of water, posing a
grave threat to local communities.
Using the word "grave" in the above sentence adds all the following tones to the
sentence EXCEPT:
(A) formal
(B) sarcastic
(C) serious
(D) pessimistic
4 Read the following selection from the article.
Laurent Bollinger is a seismologist, a scientist who studies
earthquakes, at the French Alternative Energies and Atomic
Energy Commission. He has studied the effects of the
earthquakes that hit Nepal earlier this year. According to
Bollinger's research, the earthquakes destabilized the region,
making a "great" earthquake more likely to occur in the future.
What phrase below is the BEST definition for the word "destabilized"?
(A) to bring peace
(B) to upset people
(C) to keep the status quo
(D) to cause unrest