Three California Hidden Disasters: Tsunamis, Earthquakes and Volcanos


California, celebrated for its stunning landscapes and picturesque coastline, is also a region known for geologic activity. Nestled along the Pacific Ring of Fire, the state is susceptible to a variety of natural disasters, including earthquakes, tsunamis and volcanoes. These three hidden disasters can strike at any time.  The California Governor’s Office of Emergency Services (Cal OES) consistently monitors these hidden threats and encourages awareness to prepare for, respond to and recover from these potential disasters. Cal OES, along with state and local partners, continues to explore measures to mitigate the impacts of these disasters on California communities, providing them the information needed to stay safe.  Earthquakes  Earthquakes are perhaps the most well-known seismic hazard in California. The state’s location along the boundary of the Pacific and North American tectonic plates makes it highly susceptible to seismic activity. The famous San Andreas Fault, which stretches approximately 800 miles through California, is a significant source of concern. When stress along the fault is released, it can result in powerful earthquakes.  California has experienced numerous significant earthquakes throughout its history, such as the 1906 San Francisco earthquake, the 1989 Loma Prieta earthquake and the 1994 Northridge earthquake. These events caused widespread destruction and loss of life. To mitigate the impact of future earthquakes, Cal OES and its partners have invested in public outreach and retrofitting programs for Californians to better endure earthquakes and their aftershocks.     In August 2023, a 5.1 magnitude earthquake occurred in Ojai, coincidentally during Tropical Storm Hilary, serving as a reminder that earthquakes can occur at any time. Cal OES continues to encourage residents of the Golden State to prepare for earthquakes with the following safety tips: 

  • Sign up for alerts: Download or sign up for emergency alerts at 
  • Secure your space: Identify hazards in the home and if possible secure moveable items such as bookshelves, dressers and televisions.  
  • Create an emergency plan: Customize an emergency plan with household members or family based on your specific needs.  
  • As shaking starts: 
  • In a car: Pull over, stop, set the parking brake. 
  • In bed: Turn face down, cover your head with a pillow. 
  • Outdoors: Stay away from buildings, don’t go inside. 
  • Indoors: Drop, cover and hold on to a table or desk.  

Learn more:  Tsunamis  California has 1,200 miles of coastline. Due to the state’s extensive exposure to the Pacific Ocean, tsunamis can pose a significant threat to coastal communities. The 1964 Alaska earthquake, for instance, generated a tsunami that caused damage to the town of Crescent City in Humboldt County. Most recently the 2022 Tonga volcanic eruption triggered the fastest underwater flow ever recorded, causing state and local partners to issue tsunami warnings along the coast.  A tsunami is a series of large ocean waves typically generated by large undersea earthquakes that displace the ocean floor. A tsunami can also be generated by landslides and volcanic eruptions. When the waves enter shallow depths near a coastline, they may rise to several feet or, in rare cases, tens of feet. A tsunami’s threat period can continue for many hours after a major earthquake. Tsunamis can occur during any season of the year and at any time, day or night.  To mitigate the risk of tsunamis, Cal OES’s Earthquake, Tsunami and Volcano program continuously monitors, researches and collaborates with science, industry and academic experts.  To prepare:  

  • Sign up for local emergency alerts. 
  • Create a go-bag if you need to evacuate. 
  • If you are in a tsunami zone, practice your evacuation route. 
  • Listen to local authorities. If you are in a tsunami zone marked by signs, follow posted signs to a safe area. 
  • Seek higher ground or inland and avoid river valley roads. If you are in a tsunami zone marked by signs, follow posted signs to a safe area.  

Volcanoes  While not as commonly associated with California as earthquakes, the state does have active volcanoes, albeit less active than those found in the Pacific Northwest. The most famous of these volcanoes is Mount Shasta, a massive stratovolcano in the northern part of the state. While it has not erupted in over a century, the potential for future eruptions remains. There are a total of eight volcanic threats in California.  A volcano is essentially an opening, or vent, in the earth’s crust from which hot molten rock, gases and volcanic ash escape to the surface. They may erupt explosively or effusively seep out lava. Formed as a result of plate tectonics, volcanic eruptions can result in the formation of mountains, craters, crater lakes, plateaus and islands.  Volcanoes are classified as active, dormant or extinct. An active volcano is the one that erupts or causes seismic activity on a regular basis over hundreds or thousands of years. A dormant volcano is one that has not erupted for a very long time but could erupt again in the future. And, a volcano that has been dormant for more than 10,000 years is considered an extinct volcano.  Volcanic eruptions in the state are not currently imminent. Using the threat levels, these volcanic areas are monitored continuously by Cal OES along with state and local partners. Cal OES utilizes reporting from scientific experts, along with the recently released National Volcanic Threat Assessment, to initiate state level response planning.  To prepare for Volcanoes:  

  • Determine your risk through this MAP. 
  • Obtain and store proper respiratory protections like an N-95 mask or air purifying respirator. 
  • Create an emergency preparedness plan with family or household members. 
  • Know how to turn off household utilities. 
  • Listen to local authorities for evacuations. 
  • Create an emergency go-bag with essential items and important documents in case of evacuation. 

California’s three hidden disasters –earthquakes, tsunamis and volcanoes – underscore the importance of preparedness and resiliency for all communities statewide. Cal OES not only continues to help these communities respond to and recover from these natural disasters but also is active in its public outreach efforts to offer preparedness education and mitigation for all residents of the Golden State.