One hundred eleven years ago today, on April 18 at 5:12 a.m., a violent earthquake shook San Francisco.

 

This was 30 years before the Richter scale was developed to measure an earthquake’s magnitude, and nearly 70 years before the system we use today, the Moment Magnitude scale. The scale ranks an earthquake on a scale of 1 – 10, with 10 being the most catastrophic. Each step accounts for 32x increase of energy expended.

The 1906 earthquake is estimated to have been a 7.8. For comparison, an average tornado is around 4.8, the atomic bomb on Hiroshima was about 6.2, and a Mt. St. Helen’s eruption is about 7.6.

When you consider the damage done by the earthquake (and most disasters), it is really incredible to think about how quickly they happen. In 1906, the timeline was very short:

5:12 a.m. Strong foreshock occurs, lasting 23 seconds.

5:13 a.m. The main shock occurred, and it lasted 42 seconds.

And it was over by 5:14 a.m. But several separate forces – the damage from the earthquake, the aftershocks, and the gas lines that provided energy to the city – collided with one another and a fire ignited. The city burned for three days.

But San Francisco was destined to be more than a sepia-toned memory. The people refused to let the city lay in ruins, or to scatter and rebuild elsewhere. San Francisco defiantly built itself back up, grander and more flamboyant than before. The fingerprints of the old earthquake are faded but visible,  a reminder of San Francisco’s great courage and resilience.