Tangshan: The Deadliest Earthquake

At 3:42 a.m. on July 28, 1976, a magnitude 7.8 earthquake hit the sleeping city of Tangshan, in northeastern China. The very large earthquake, striking an area where it was totally unexpected, obliterated the city of Tangshan and killed over 240,000 people - making it the deadliest earthquake of the twentieth century.

What was the biggest earthquake ever?

The biggest earthquake known in historical times occurred on 22 May 1960 in Chile, with a magnitude Mw of 9.5. It occurred because of a rupture in the Earth's crust that extended horizontally about 1000 km along the coast of South America; in some places this quake caused vertical uplifts as large as six meters. The second biggest earthquake known, with a magnitude of 9.2, occurred in Alaska on 27 March 1964; it had a rupture length of 800 km, and caused as much as 11 meters of uplift.

Theoretical calculations suggest that these earthquakes are just about as large as possible for planet Earth. Suppose a hypothetical earthquake ruptures the entire 100 km thickness of the rigid tectonic plates, and suppose this rupture extends along a fault with length 1000 km with an average slip of 10 meters. Calculations show that this hypothetical earthquake would have a magnitude of about 9.3. Larger earthquakes would have to rupture an even longer fault with an even greater average slip; apparently this just doesn't happen.

What was the most deadly earthquake ever?

The 27 July 1976 earthquake in Tangshan, China (MS = 7.9) caused the greatest number of deaths of any recent quake known; the most reliable estimates are that about 242,000 lives were lost. Tangshan had a pre-quake population of about a million people; the main industry is mining. One reason the death toll was so high is because most of the structures in Tangshan were multiple-story, unreinforced brick and concrete buildings.

Estimates of loss of life from the worst earthquake disasters are very unreliable; understandably, when tens of thousands of people are dead and most buildings are in ruins, there are more important things to do than to count bodies. However, there have been about five quakes in the twentieth century where reports of lives lost exceeded