At 10 a.m. Nov. 13, more than 3.5 million people in homes, schools, businesses, government offices and public places all over Southern California will drop, cover and hold on during the largest earthquake preparedness drill in U.S. history. The Great Southern California ShakeOut Drill will start with a magnitude 7.8 earthquake on the southern San Andreas fault, one approximately 5,000 times larger than the magnitude 5.4 earthquake that shook Southern California on July 29. Lisa Grant Ludwig, public health professor and local earthquake researcher, was key in the development of the ShakeOut scenario.

Q: For years, we’ve been warned about “the big one.” As a researcher, have you come across clues indicating when or if it will happen?

A: There is no question about if it will happen. Data from several recent studies, including from my research group, show the San Andreas fault has generated a large earthquake approximately every 100 years, and it has been 151 years since the last “big one” in Southern California. There are several ways to calculate probabilities, but they all agree that a large earthquake is likely in our lifetime – it is geologically inevitable. People tend to ignore this problem, in part because scientists can’t say exactly when it will happen. By analogy, if you knew you were on course for a head-on collision, would you waste time wondering when? Or, would you take action to improve your chance of survival? I can’t tell you when, but I can tell you it is time to tighten your seat belt, step on the brakes and make sure your airbag is functional because sooner or later we’re going to crash.

Q: The centerpiece of the ShakeOut is a doomsday 7.8 earthquake. Why did you develop a scenario featuring such a devastating temblor?

A: Because it is realistic. Our data show that similar earthquakes happened here in the not-too-distant past. As Shakespeare said, past is prologue. In the past, large earthquakes on the San Andreas fault affected very few people. Now, millions of people are at risk. Earthquakes cannot be prevented, and the severity of impact depends on what we do – or don’t do – between now and when they occur.

Q: What have you learned about the network of faults in Southern California?

A: “Network” is a good term to describe the system because there are many active faults that generate earthquakes. The San Andreas has the highest probability of generating a “big one” but the network of smaller faults adds significant risk. By comparison, the recent May 2008 Wenchuan earthquake in China is a good example. The earthquake occurred on a fault that received little attention until it killed almost 90,000 people, injured 375,000 and caused nearly $1 trillion in damage. The Southern California landscape was shaped by a network of similar faults linked to the larger San Andreas.

Q: What are common misperceptions about earthquakes?

A: Earthquakes happen during earthquake weather. California will fall into the sea in the next big one. Since earthquakes can’t be prevented, there is nothing you can do to protect yourself.

Q: What do you hope can be learned from the ShakeOut?

A: I hope people will learn what a big earthquake means – for them, their loved ones and their livelihood. I hope they will learn where and how they are vulnerable, and what they can do to improve their chances of riding it out safely. This already has happened among the scientists and others involved in developing ShakeOut. We’ve had a preview of what such an earthquake will look like. It will be scary to live through and miserable to survive. Just think – how would you function without water for weeks? Can you take care of yourself and your loved ones without electricity and plumbing? Forget phone, Internet and ATM cards. It will be our Hurricane Katrina without the ability to evacuate. Now is the time to learn what you can do to protect yourself and your family.
Q: Everyone is aware of the need for earthquake preparedness. How much preparedness is necessary?

A: This is a question everyone in Southern California should ask themselves. Assume you will be taking an unscheduled camping trip with your family or co-workers for several weeks – possibly several months. There will be no potable tap water or plumbing or electricity or convenience store or telephone. What should you pack?