Notable Earthquake of the Week

Tangshan, China, M8.2 Earthquake  

On July 28, 1976, at 3:42 a.m. local time, a powerful earthquake registering M8.2 occurred in northeastern China about 95 miles east of Peking near Tangshan, an industrial city of about 1 million people. Many eye witnesses said they saw a bright flashed across the sky which was followed by a deafening roar just before the shaking began.

Vigorous shaking lasted for several 10's of seconds and registered a Modified Mercalli Intensity rating of XI at the epicenter (a relative scale rating the intensity of shaking from 1-12 in Roman numerals). A robust aftershock sequence followed and culminated about 18 hours later when another powerful M7.6 earthquake struck just outside Tangshan. Buildings that were partially damaged during the first temblor were wrecked by the second and many participating in rescue attempts were killed. The city was described by some as being totally destroyed, with few buildings left standing.

Officially, the Chinese government estimated between 240,000 and 250,000 people were killed with an additional +600,000 were injured. In the decades since the quake, the death toll has been estimated closer to half a million. Either number would make this the most deadly quake in the twentieth century.

The quake was centered along the Tancheng-Lujiang, or Tan-Lu, fault , a large north-northeast - south-southwest trending fault system which extends for over 3,200 miles from the north bank of the Yangtze River in eastern China across the Russian border. The motion of the fault during was predominantly strike-slip with maximum horizontal displacements on the order of 7 meters or 22 feet.

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