Earthquakes in China

1
Earthquakes in China

• Eastern Sichuan province
• Near city of Chengdu
• 228 pm May 12, 2008

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5

• 7.9 magnitude on the Richter scale
• Shook Beijing (930 mi N), Shanghai, Thailand,
  Vietnam, Pakistan.
• Affected 10 million people killing 15, 000
• Lasted 2 min
• Epicenter was only 6 miles deep

6
Richter Earthquake Magnitude Effects

• Used to measure Earthquake Severity
• Less than 3.5 Generally not felt, but
  recorded.
• 3.5-5.4 Often felt, but rarely causes
  damage.
• Under 6.0 At most slight damage to
  well-designed buildings. Can cause
• major damage to poorly
  constructed buildings over small regions.
• 6.1-6.9 Can be destructive in areas up
  to about 100 kilometers across
• where people live.
• 7.0-7.9 Major earthquake. Can cause
  serious damage over larger areas.
• 8 or greater Great earthquake. Can cause
  serious damage in areas several hundred
• kilometers across.

7
Damage

• Eighty percent of the buildings collapsed
• May be 50,000 people dead
• At least six schools collapsed
• Telephone and power networks were destroyed
• Roads were damaged/blocked
• 5 million people homeless
• Dams may be cracked

8
Landslides Refugees, soldiers and rescue workers
carry survivors out of the county town of
Beichuan. The landslide that buried much of the
town is visible in the background.
9
Why was there a big earthquake here?
10
Faults in China
11
Plate tectonics
12
Plate tectonics
13
Why so many earthquakes?
14
Results of Plate tectonics

• northward collisional convergence (at about 50
  mm/y) of the India tectonic plate against the
  Eurasian plate.
• begun about 55 million years ago
• has uplifted the Asian highlands and the Tibetan
  Plateau to an average elevation of over 16,000
  feet - the highest and largest plateau on Earth
• India has pushed into Asia at least 1,200 kms

15
A folded, faults land
The strong folds control the flow of
rivers Sediments collect in rivers Cities and
villages often build on the rivers Soft
sediments shake more in earthquakes Earthquakes
are more destructive Scientist predict more
serious earthquakes for the future.
16
Los Angeles computer earthquake

• Movie

17
Why so strong?

• Longmenshan Fault
• 155 miles long
• 2 stages slipped in two places
• 1st 7 m, 2nd 4 m
• Very hard land in the area
• Waves travel far, and stay strong
• Waves slow down in softer land
• Had at least seven major aftershocks -- measuring
  between 4.0 and 6.0 magnitudes
• Have been many serious earthquakes in China

18
(No Transcript)
19
(No Transcript)