“IT was horrible. We were lost. It was like an ocean, an ocean, everything moving.”

So said a survivor of one of the most lethal earthquakes on record. That devastating earthshock struck in 1976 in China, leveling the city of Tangshan and snuffing out some 800,000 lives. Amazingly, that escapee was able to struggle barefoot out of a hotel that, along with 20 square miles (52 sq km) of cityscape, had collapsed into rubble.

Consider Tangshan. It was just a hamlet until the 1870’s. If the 1976 quake had struck then, fatalities could not have exceeded the small number of residents. In 1879 industrial development began. By the 1970’s the population had grown to over a million, setting the stage for grave disaster in 1976.

Furthermore, comparisons based simply on the Richter scale can be misleading. For example, the 1964 earthquake in Alaska killed 115 people and was 8.5 on the Richter scale. The Tangshan quake was rated lower at 8.2. Which one was truly greater? Measured by the human toll rather than by the Richter scale, the Tangshan event was clearly worse, the most severe of the 20th century. Instruments cannot measure the magnitude of human distress.