If you count tremors prior to the quake and aftershocks, earthquakes can last for months. But the central event lasts only seconds or minutes.
The great San Francisco earthquake of 1906 began when the ground shuddered for about a minute at 5:11 A.M., April 18. Ten seconds of quiet followed. At 5:12 A.M., the major quake-7.9 on the Richter scale—began.
Three minutes later, it was over, leaving thousands of buildings in pieces, broken gas mains, buckled streets, and raging fires. Ultimately, 75 percent of the city was destroyed.
The disastrous earthquake in Mexico City on the morning of September 19, 1985, also lasted 3 minutes. In that time, 250 buildings were leveled. The next day another quake destroyed another 150 buildings and put a stop to the first earthquake’s relief work.