Arizona, a state more often associated with stunning desert landscapes and iconic natural landmarks like the Grand Canyon, is not commonly thought of as a hotspot for seismic activity.
Yet, buried in its geological history is a powerful tremor that rattled the state and left an imprint on both its residents and researchers.
This is the story of the largest earthquake ever recorded in Arizona.
A Rare but Powerful Event
While California, Alaska, and other western states regularly dominate earthquake headlines, Arizona typically lies outside the seismically active zones of the Pacific Ring of Fire. However, that doesn’t mean the state is immune to earthquakes.
The largest earthquake to ever strike Arizona occurred on January 25, 1935, near the town of Duncan, located in southeastern Arizona along the border with New Mexico. This quake registered an estimated magnitude of 6.5 on the Richter scale, a surprisingly powerful jolt for a region generally considered geologically quiet.
The 1935 Duncan Earthquake
At approximately 6:03 a.m., residents in Duncan and surrounding areas were shaken awake by a forceful tremor that lasted nearly a minute. The earthquake originated near the Peloncillo Mountains, a lesser-known fault system that was not fully understood at the time.
Although the quake occurred in a relatively remote and sparsely populated area, the damage was still significant. Buildings made from adobe, common in that region during the early 20th century, suffered the worst. Homes cracked or crumbled, chimneys collapsed, and frightened families rushed outside, fearing aftershocks.
Miraculously, no fatalities were reported, though there were numerous injuries and property losses. The quake was felt as far away as Phoenix, Tucson, El Paso, and even Albuquerque, New Mexico.
Geological Impacts and Fault Activity
The 1935 quake helped draw attention to the Arizona-New Mexico Seismic Belt, a zone of tectonic stress that had previously been underestimated by geologists. Although Arizona lacks the major fault lines seen in California—like the San Andreas Fault—it does sit above minor fault zones and buried geological structures capable of producing moderate to strong quakes.
Researchers later linked the quake to a strike-slip fault associated with crustal stretching occurring in the Basin and Range Province, a vast geological region that includes parts of Arizona, Nevada, and Utah. The horizontal movement of this fault caused the intense shaking.
A Wake-Up Call for Preparedness
In a state where earthquakes are relatively rare, the 1935 event served as a wake-up call. While Arizona doesn’t face the same earthquake risk as neighboring California, experts warn that complacency could be dangerous.
“We don’t see large earthquakes often in Arizona, but they can happen,” said Dr. Lisa Holley, a geophysicist at Arizona State University. “The Duncan quake of 1935 reminds us that even in low-risk areas, we need to prepare for worst-case scenarios.”
Despite the lessons of the past, Arizona’s building codes and public awareness campaigns have not historically emphasized earthquake preparedness. Today, efforts are underway to change that. Seismic monitoring stations have been added in key parts of the state, and emergency response teams conduct periodic drills in case of a similar event.
Could It Happen Again?
According to the U.S. Geological Survey (USGS), Arizona continues to experience small tremors every year. These are often too minor to be felt, but they are closely monitored. The most recent widely felt quake occurred near Sedona in 2015, measuring a magnitude 4.1. Though far less powerful than the Duncan earthquake, it reminded residents that the ground beneath Arizona is not completely still.
Experts believe that another 6.0+ magnitude quake is possible, particularly in the southeastern corner of the state. Although such events may be centuries apart, Arizona’s growing population and development in vulnerable areas raise concerns about future impacts.
Modern Day Risk and Earthquake Safety
Even though the 1935 earthquake predates most modern infrastructure, its lessons are still relevant today. If a similar quake were to strike today near cities like Tucson or Flagstaff, the consequences could be far more severe.
Key safety measures for Arizona residents include:
- Securing heavy furniture and appliances.
- Keeping emergency kits with water, food, and medical supplies.
- Knowing evacuation routes and safe places in the home.
- Participating in statewide earthquake drills when available.
State officials have partnered with organizations like the Arizona Geological Survey and ShakeOut.org to raise awareness about seismic safety. “Preparedness is not about fear—it’s about resilience,” said Arizona Department of Emergency and Military Affairs spokesperson Anna Ramirez. “You may only experience one big quake in your lifetime, but being ready can save lives.”
Conclusion
Arizona’s largest recorded earthquake—a magnitude 6.5 in Duncan in 1935—stands as a dramatic reminder that seismic events can and do occur outside traditional earthquake zones. While the state may not be known for ground-shaking disasters, history shows that it is not immune. Understanding this event, preparing for future quakes, and spreading awareness are crucial steps toward a safer and more informed Arizona.