Natural Disaster History: Tangshan Quake, 1976

In Natural Disaster History this month, the Tangshan earthquake

In the wee hours of July 28, 1976, the deadliest earthquake of last century occurred in Hebei province, China. The death toll, while still uncertain, may have been as much as a half million.

As with many earthquakes, the destruction was caused a pair of shakes, the big aftershock coming sixteen hours after the main shock. With magnitudes of 7.5 (revised) and 7.1, the earthquakes lasted no more than fifteen seconds each. Despite what might look like moderate magnitude numbers, the shaking intensity for the central 47 square kilometer affected area was 11 (on a scale of 12).

The weakness of home construction combined with the nature of the soil beneath them was responsible for much of the death; the hour of the quake was also a factor, as nearly everyone was in bed, sleeping. In that fifteen seconds of shaking, few had the time even to dive under a piece of heavy furniture for protection as the roofs came crashing down on them. Of those awake and working, some were coal miners who are assumed to have perished underground.

According to some reports, the destruction in the city of Tangshan (population 1.6 million at the time) was so complete, not a single hospital remained standing. In addition, water, electricity, and sewage infrastructures were destroyed. Highway overpasses and bridges collapsed and rail lines were so bent that travel on them was impossible. Food delivery was therefore nearly impossible to effect. Near the sea, sand volcanoes erupted from the layers of saturated silt underground. Because news reports did not flow readily out of China at the time, we were then--and still are--uncertain about many details.

The death toll is difficult to nail down because of political issues, and it may have been exacerbated by politics as China refused international aid, trying to prove that the Revolution meant they could handle such matters entirely on their own. Volunteer efforts to immediately dig neighbors from the ruble did save lives, as it would today, in your town, were an earthquake like this to strike there.

Sources: Wikipedia, BBC, National Geographic, USGS. If you are interested in more, there are a couple of short videos in Mandarin on youtube, which provide images.