In the early morning of April 18th, 1906, residents of San Francisco were shaken from their slumbers. Also shaken were their belongings, which tumbled from tables and shelves, and their homes, many of which were flattened. The Great San Francisco Earthquake had struck. Over 500 people lost their lives in the disaster and subsequent fires.
Weeks later, the rebuilding process was in full swing, as was the quest to historically document the quake. In the midst of this mission, a curious story surfaced:
Paine Shafter, a ranch owner living just outside of San Francisco reported that during the quake the ground suddenly and swiftly opened up and swallowed one of his milking cows whole, and seconds later, "the crack closed and left just her head and tail sticking out."
A peculiar sight, indeed; but did it actually happen?
To answer this question, one must first know a bit about fissures - long gaps or cracks in the ground. For starters, most fissures that result from earthquakes are not directly created by the quakes, themselves. They form due to associated landslides or slumps tied to the rapid withdrawal of groundwater.
"Most such cracks are on unconsolidated ground (as opposed to bedrock)," University of Utah seismologist James Pechmann told RCScience. "They can develop from shaking, settling, and 'lurching' of the ground during an earthquake..."
These common fissures take time to form and are often no more than a few feet deep. But occasionally, they can be quite large. A fissure five kilometers in length formed after an 1868 earthquake in Hawaii! But this fissure paled in comparison to another that developed in the wake of Mongolia's gigantic 1957 quake. This crack was over 250 kilometers long, as deep as 36 feet, and as wide as 10 feet!
The fissure type perpetuated by Hollywood -- where the ground rapidly ruptures and swallows unsuspecting bystanders - is almost certainly a myth. When a normal fault slips, the soil near the surface can potentially rip apart, creating jagged cracks in the ground up to a meter in width. However, fissures of this variety aren't very deep or long -- you could probably safely stand in them -- and they definitely don't spew red-hot lava or seal themselves back up.
This information renders the story of a dairy cow getting swallowed by the earth hard to swallow. It also does the same to an alarming U.S. army report filed in the wake of Japan's 1948 Fukui Earthquake. According to the report, soldiers witnessed a Japanese woman working on a rice paddy fall into a four-foot-wide fissure, which subsequently closed and crushed her. That could very well have happened, but it probably didn't.
And by more recent accounts, the case of the crushed dairy cow definitely didn't happen. Many years after the 1906 earthquake, H.H. Howard, a cousin to Paine Shafter, sent a letter to the historian Robert Iacopi. In the message, Howard recalled a candid conversation between Paine and his father, Pax:
"Look Pax," [said Paine], "the cow had died, and we had to bury her. That night along came the earthquake which opened up a big crack and tipped it in, with the feet sticking out. Then along came those newspaper reporters and... we weren't about to spoil a good story..."