Southern California is earthquake country. It always has been—and it always will be. While scientists cannot predict exactly when the next major earthquake will strike, they agree on one fundamental truth: it’s not a question of if, but when.

The greatest risk is not the earthquake itself—it’s how prepared we are when the shaking begins.

Learning From Our Earthquake History

Many Angelenos remember the 1994 Northridge Earthquake, a magnitude 6.7 event that struck without warning in the early morning hours. It collapsed freeways, damaged tens of thousands of homes, injured more than 9,000 people, and became one of the costliest natural disasters in U.S. history.

Less than a decade earlier, the 1987 Whittier Narrows Earthquake reminded Southern California that even moderate earthquakes can cause serious damage—particularly in older buildings and dense urban neighborhoods.

Neither of these events was considered “the Big One.” Yet both caused widespread disruption, injuries, and long-term recovery challenges.

The San Andreas Fault: Overdue, Not Overhyped

The San Andreas Fault is California’s most well-known and powerful fault system. Stretching more than 800 miles across the state, it marks the boundary between the Pacific and North American tectonic plates and is capable of producing earthquakes larger than magnitude 7.8.

Geological evidence shows that major earthquakes on the southern portion of the San Andreas tend to occur every 130 to 160 years. The last major rupture occurred in 1857.

That means the fault is now more than 150 years overdue for a major release of built-up energy. “Overdue” does not mean imminent—but it does mean the risk is real, ongoing, and unavoidable.

What About Earthquake Swarms?

In recent years, Californians have experienced earthquake swarms—clusters of small earthquakes occurring over short periods of time. These events often raise concerns about whether a major earthquake is about to follow.

It’s important to understand that earthquake swarms are not proof-positive indicators of an impending large earthquake. In many cases, swarms occur without leading to a larger event. Scientists continue to study these patterns, but there is currently no reliable way to predict exactly when or where a major earthquake will occur.

What swarms do provide is a powerful reminder: California’s fault systems are active every day.

California’s Most Threatening Fault Lines

Especially Relevant for Southern California

While the San Andreas Fault often dominates headlines, it is only one part of a complex network of active fault systems—many of which run directly beneath heavily populated communities.

San Andreas Fault

Potential magnitude: 7.8+

Capable of causing widespread, statewide impacts affecting transportation, utilities, water systems, and millions of residents.

San Jacinto Fault

Potential magnitude: 7.0–7.5

One of the most seismically active faults in California, posing serious risk to Inland Empire communities.

Elsinore Fault

Potential magnitude: 7.0–7.4

A slower-moving but dangerous fault affecting Riverside and northern San Diego counties.

Newport–Inglewood Fault Zone

Potential magnitude: 6.5–7.4

Runs beneath some of Southern California’s most densely populated areas and was responsible for the 1933 Long Beach Earthquake.

Puente Hills Thrust Fault

Potential magnitude: 7.2–7.5

A buried (blind) fault beneath Los Angeles capable of producing severe shaking across the entire basin.

Hollywood Fault

Potential magnitude: 6.0–6.5

A localized but serious threat due to its proximity to dense neighborhoods and older structures.

Sierra Madre Fault Zone

Potential magnitude: 6.5–7.0

Affects foothill communities along the San Gabriel Mountains and poses landslide risks in addition to shaking.

Why Fault Location Matters

Earthquakes don’t need to be massive to be devastating. Faults that run directly beneath urban areas can cause:

• Severe shaking in older buildings
• Disruption to power, water, and transportation systems
• Long-term displacement of residents

This is why earthquake preparedness must be local, realistic, and proactive.

The Best Time to Prepare Is Now

Earthquakes provide no warning. There is no evacuation order, no countdown, and no opportunity to prepare once the shaking begins.

Preparation happens before the earthquake.

That means:

• Securing heavy furniture and appliances
• Having emergency supplies for at least 3–7 days
• Creating a family communication and reunification plan
• Knowing how to shut off gas and utilities
• Understanding what to do during and after an earthquake

Preparedness is not about fear—it’s about resilience.

MySafe:LA Is Here to Help

At MySafe:LA, we believe informed communities save lives. Through education, training, and community-focused initiatives, we help Angelenos understand their risks and take practical steps to reduce them—before disaster strikes.

The next big earthquake may not happen tomorrow. Or next year. But it will happen.

Preparedness today is the difference between chaos and resilience tomorrow.