Why Mobile Phones Didn't Work After Virginia Earthquake

News Analysis: Every time we have a major man-made or natural event, like the stunning Aug. 23 earthquake in Virginia that shook most of the East Coast, mobile phones stop working. You should plan to live without your mobile service in such emergencies.

The earthquake that struck the U.S. East Coast Aug. 23 was a real surprise for nearly everyone. First of all, the East Coast rarely gets earthquakes that are big enough to feel.

Furthermore, this one was big enough to cause property damage.

The result of this was that anyone with a phone on the East Coast was calling someone else to say (as I did) "Hey! We're having an earthquake!" Of course, there were also calls to report that one was O.K., or calls to see if someone in the affected area was O.K. Finally, there were thousands of calls of derision from people on the West Coast, "Ha! Is that all you got?"

These callsjammed phone networks everywhere near the affected area. Cell systems were overtaxed; landlines had problems handling calls; and the switching centers were trying to cope with far more calls than normal. Adding to this was a scare caused by a rogue Tweeter saying that cell towers were down everywhere. For a few minutes, many people were in a state of panic.

But what's stranger than the fact that people panicked about the clogged networks is the fact that many of these same people panicked the last time the networks were clogged. Depending on where you happened to be, this might have been Hurricane Katrina or it might have been the Giants winning the 2010 World Series, which jammed networks in San Francisco even without the chaos of an earthquake.

Cellphone networks get jammed because the cell sites are only designed to handle a certain number of calls at the same time. Likewise, the switches that the wireless companies use can only carry a specific number of calls at the same time. This is compounded because the cell phones of first responders and others with critical jobs have a priority code attached to their call so they get access to the cell site even if it means kicking you off.

Wired phone systems have similar capacity problems, of course, and their switches can also get overloaded. But it's cell phones that get the most notice. After the recent quake, for example, wireless carriers reported that their systems were clogged for periods, ranging from 30 minutes to nearly an hour. What this means to you is that you and your business need to have a plan for communications during an emergency that doesn't involve making calls on your cell phone.

Wayne Rash

Wayne Rash

Wayne Rash is a freelance writer and editor with a 35 year history covering technology. He’s a frequent speaker on business, technology issues and enterprise computing. He covers Washington and...