From a Californian: What East Coast residents should know about earthquakes

SAN FRANCISCO — Californians waking up to the news that an earthquake measuring 4.8 on the Richter scale rattled buildings and nerves in New Jersey and across much of the East Coast Friday morning — but caused no reported damage — could be forgiven for reacting with a shrug. After all, the Golden State experiences 25 quakes each year that range between magnitudes of 4.0 and 5.0.

Yet it was surprising for many people to learn that New Jersey lies upon the Ramapo Fault system, which was responsible for the state’s largest earthquake, a 5.3 temblor, in 1783 and a 5.5 quake in New York City in 1884. Richter scale readings above 4.0 are certainly big enough to cause damage, though not nearly to the extent of 1994’s 6.7 magnitude Northridge earthquake or 1989’s Loma Prieta quake, which registered 6.9 and lasted roughly 20 seconds just as a World Series game between the San Francisco Giants and the Oakland Athletics was about to get underway.

What’s in a number?

On its website, the United States Geological Survey notes that “there is not one magnitude above which damage will occur.”

Yet as many Californians have learned, the Richter scale is logarithmic, meaning that for each whole number you go up, the shaking on the ground as measured by a seismograph increases 10 times.

Ready or not?

In 1811, the strongest earthquake to occur in recorded history in the continental U.S. struck the Mississippi River town of New Madrid, Mo. The initial quake is believed to have measured between 7.2 and 8.2 and caught the European settlers and Native Americans who lived there at the time completely unaware. Scientists later dubbed the region the New Madrid seismic zone and have studied the underlying causes for a major earthquake nobody saw coming.

In California, we are well-versed in the names of major fault lines — like the San Andreas and the Hayward, the latter of which runs underneath my home in the East Bay — and we are regularly urged to prepare an earthquake survival kit. At a minimum, that should include a several-day supply of food and water, a flashlight, a crank radio and extra batteries, a first aid kit, a cellphone and a charger.

In November, state and federal officials held what they dubbed Great Shakeout Earthquake Drills, “an annual opportunity for people in homes, schools, and organizations to practice what to do during earthquakes and to improve preparedness.”

The state also offers grants to homeowners to help cover the cost of bolting homes to their foundations to keep them from collapsing during earthquakes.

And California is the first state in the nation to use an earthquake early warning system that can, through alerts on cellphones, buy residents a few precious extra seconds to prepare before a big earthquake hits. The system also delivers alerts to mass transit systems, shutting down train lines when the shaking starts.

How much should East Coasters worry about earthquakes?

The reason Californians have become so accustomed to earthquakes is relatively simple: We live over active fault zones that cause them. Those familiar with plate tectonics may know that California’s coast is located on the boundary of two plates and is part of the Pacific Ring of Fire, a zone that circles the Pacific Ocean and accounts for 80% of the world’s earthquakes.

By comparison, the East Coast is 100 times less active than California when it comes to seismic activity, Forbes reported, and there is no reason to believe earthquakes will become more frequent in the coming years.

That said, some geologists note that the Ramapo Fault system presents risks. In a 2001 interview with the New York Times, Alexander Gates, a geology professor at Rutgers University-Newark, said that the New York area was ripe for another significant shaker.

“We should not forget that we had a 5.4 earthquake 117 years ago,” he said at the time. “The recurrence interval for an earthquake of that magnitude is every 50 years, and we are overdue.”

While the probability of a major earthquake may not be as high on the East Coast as it is in California, that doesn’t make experiencing one any less frightening.