That Sinking Feeling
by Carol Camelot
July 29, 2010

The mysterious case of the disappearing house, or street, or even a town. When those on the surface, thinking they are safe, suddenly plummet down into the crust of the earth. Fortunately, it does not happen that often.
A true sinkhole is due to karst processes – the chemical dissolution of carbonate rocks. In popular usage by the media and public, however, sinkholes refer to a depression or cavity which opens up. Sinkholes can occur due to excessive rainfall or water seeping into crevices which expand, with the weight of rock and soil above them becoming too heavy. Also, additional causes are underground water pressure changes, failure of old water or sewer pipes, and even tectonic movement of the crust (which may cause water and sewer lines to pull apart and rupture). Sometimes an earthquake tremor is not the cause – but rather a stretching of the land itself, like a rubber band too taut.

Being a consultant in the disaster readiness field, I pay close attention to a number of key indicators – and the number of sinkholes has been increasing worldwide for years now. Missouri, Florida, Kentucky, Tennessee, Texas, Alabama, California and others have sinkholes occurring. Too numerous to enumerate, this column focuses on those closer to home. Holes can be a foot across and in depth or large enough to swallow up homes and streets.

A 42,000 pound fire truck was swallowed by one in September 2009 in North Hollywood due to a water main break. Interstate 215 in both directions was shut down for several days due to a 25-foot-wide sinkhole in Murrieta, reported The Press-Enterprise on February 19, 2009. It damaged a drain pipe said road superintendent Gino Prudholm.

In June 2010 a car sunk into one in a Las Vegas street due to a 24 inch water line which developed a leak. Victorville residents had to avoid eight sinkholes opening up in January 2010. The original sinkhole measured 25 feet long, three feet wide and about six feet in depth. Palm Springs police diverted traffic around one large enough to engulf a car near the railroad bridge in July 2008.

Sinkholes have been known to empty entire lakes of their water. In June 2004 one disappeared in a just a few days in Wildwood, Missouri. “It’s real creepy, “ said Donna Ripp, who lives nearby. “That lake was 23 acres – no small lake. And to wake up one morning, drive by and it’s gone?”

Officials are scratching their heads trying to understand how two holes opened up in the walls of their dam. WAVY-TV 10 reported on June 18, 2010, that the town of Hope Mills in North Carolina had just completed building and filling their dam’s reservoir – and then it promptly emptied itself!

Regarding the Coachella Valley's risk, the United States Geological Report, updated September 1, 2005 states that "vertical changes in land surface ... occurred in three areas of the Coachella Valley -- near Palm Desert, Indian Wells, and Lake Cahuilla" according to measurements taken between 1996 and 1998. "Land subsidence associated with ground-water-level declines has been recognized as a potential problem in Coachella Valley, California."

So, according to my “Six Principles of Disaster Readiness” what should you do? Principle No. 4 is “Awareness of climate, political, economic and sociological conditions.” It couldn’t be too wordy so I stopped short of naming every danger and catastrophe that could befall a person. Please excuse the omission therefore of “sinkholes.”

It is highly recommended that you be prepared in your home, office and in your car with emergency supplies such as water, food, a first aid kit, flashlight and so on. Bob, a close friend of mine, drives around the country with a life jacket just in case he encounters flooding. It wouldn’t hurt to have a 50 foot length of rope in your trunk or under the seat to enable extrication from a car submerging into a sinkhole!

Just be aware that if you notice on the evening news a sudden increase in underground water and sewer pipes breaking we may find a few sinking asphalt roads around here. Look before you leap!