What If an Earthquake was Predicted to Happen in Four Days? What Would You Do??

 The Great Shakeout is planned for Oct. 16, 2025, at 10:16 AM. 

And why aren't you doing it now?!

Art by Zeo

NOTE: THIS IS HYPOTHETICAL, NOT A REAL PREDICTION!

It is reported that there is a 50% chance that your region is going to be hit with a magnitude 7.5 earthquake within the next four days. What are the most important things you would do in response to this prediction? What questions would you ask?

This is an exercise I do with my students and their responses are quite extensive, and exceedingly logical. They speak of storing up water and food supplies, checking their first aid kits, preparing family emergency plans, and oftentimes, evacuating the region and getting away from the quake damage.

They are great ideas, but some thoughts arise as they consider their options...

• If people know an earthquake is coming, there would be chaos in stores as people hoard up emergency supplies. Remember the shortages during the Covid epidemic. Or any hurricane in the last few years. 
• Traffic will be horrific, and where exactly would hundreds of thousands, or even millions of people go?
• And...how many people would actually question the source of the prediction and its reliability. Predications have caused panic in the past. We've never been able predict earthquakes on short notice before, so why would this prediction be different?

The San Andreas fault in the Carrizo Plains of Southern California

It's a real problem because millions of people in California and other parts of the country live with the threat of earthquakes. And few of them have given thought to what they would do, and they are not in any prepared for an actual catastrophe. How many people have stored up emergency water and food supplies, and how many actually have an emergency plan?

So my response to my students is this:

We cannot know precisely when an earthquake will strike, nor where. We know the potential for earthquakes for many areas, especially in California, and in many cases have a broad idea about the probability of a quake taking place within a few years or decades. 

If you live in area with possible earthquake activity, you must prepare beforehand. Otherwise you'll be a victim. The California Earthquake Authority has lots of information about how to prepare, but let my students give you the short list:

• Become familiar with the risk of quakes where you live. Know what possible level of magnitude and shaking you could face.
• Have emergency supplies of water and nonperishable food sufficient for at least a week
• Have a first aid kit handy and know how to use it (emergency services will be overwhelmed)
• Consider how you will deal with the loss of power, phone service, and water for at least week
• Have a go-bag of clothing, medicines, important documents in your vehicle or at least close at hand (a good idea for many kinds of emergencies)
• Have an emergency plan in place for all members of your household

Be prepared!!

Myths and Misconceptions about California and Earthquakes for the Day of the Great Shake-Out!

Today is the Great Shake-Out in California: At 10:18 AM, around 9 MILLION people participated in a statewide earthquake drill. This is also the day after the 23rd anniversary of the Loma Prieta earthquake that caused so much damage in the San Francisco Bay-Santa Cruz region, and given that many people in northern California weren't even born by then, and others have moved in, it helps to be reminded that earthquakes are a fact of life in our fair state (and our state is quite fair because of the long-term activity of earthquakes: it's how our mountains formed). Last year I posted a series of assumptions that people sometimes make about California and earthquakes, and it seemed to be a good time to dust off some of these old posts...

It starts with a modest little quiz....

True or False?

• California is going to fall into the Pacific Ocean
• The San Andreas fault causes all California earthquakes
• California has more earthquakes and bigger earthquakes than anywhere else
• The ground opens up and swallows people during earthquakes
• Psychics and animals predict earthquakes
• We in California are waiting for the "BIG ONE"

Comic art courtesy of Zeo

The answers are pretty extensive, so click below to read more...

Just Gotta Love Days Like This...Earthquakes, Earthquakes, Earthquakes

I just love days like this...The Great California ShakeOut has people thinking about earthquakes all over the state of California, with upwards of 8 million people practicing and preparing for a major seismic event in the state. I just happen to be introducing the topic of earthquakes in my physical geology classes today. I just finished blogging about the myths of earthquakes in California. Then...two earthquakes just happen to shake the Bay Area! The events, registering magnitude 4.0 and 3.8, were felt across the region, but probably caused little damage. They took place on or near the Hayward fault, which is one of the major active fault zones in the state. It is capable of generating events in the magnitude 7 range.

The quakes today did a great job of making people aware of the seismic hazards of living in the state (and really...just HOW did the ShakeOut people arrange for actual earthquakes???). Few people were hurt, but everyone is talking about them.

There is a more ominous note in the quakes today. The Hayward fault is one of the most dangerous fault zones in California at this time, partly for the size of the quakes that it can produce, but even more for the level of urbanization along the trace of the fault. A magnitude 7 quake has the potential to kill and injure tens of thousands, and to cause untold billions of dollars of damage. The U.S. Geological Survey calculates a 31% chance of a 6.7+ magnitude quake along the Hayward within the next 30 years (and only a 21% chance along the San Andreas within the same time period).

Foreshocks may often precede a major earthquake, and there is a slight chance (maybe 5%) that today's events are precursor quakes. They are reminders that to live in California is to live in earthquake country, and that it is critical to be prepared. All Californians, and especially those in the urban centers of the Bay Area, Los Angeles, and the Inland Empire should always have spare water, food and first aid supplies handy, both at home and in their cars. Find out what the hazards are in your particular area. Have a family plan for when you are separated following a major event. Check out the Great ShakeOut website for more information.

Stay safe!