A tsunami is a series of large waves generated by the sudden displacement of the ocean. Large earthquakes below or near the ocean floor are the most common cause, but landslides, volcanic activity, certain types of weather, and near earth objects (e.g., asteroids, comets) can also cause tsunamis. Most tsunamis are generated by earthquakes or landslides caused by earthquakes, and due to the unique terrain along the Santa Monica coast, residents must be prepared for these catastrophic events. Although the Santa Monica coast is great for recreational activities, tsunamis cannot and should not be surfed or swam. Tsunami waves are usually filled with life-threatening debris which can severely hurt someone, and the column of water does not have the same composition as a wind-driven wave.
If you are near the coast during a seismic event, a tsunami can be detected by strong ground shaking, a loud ocean roar, or the water receding unusually far and exposing the sea floor. A tsunami may arrive within minutes or hours later due to the proximity of the seismic activity. Tsunami waves can reach heights of 20 to 50 feet along the coast, but the first tsunami wave may not be the highest and a larger surge may occur hours after the first wave.
When a tsunami is detected, warnings will be issued by Wireless Emergency Alert, radio, television, telephone, text message, and door-to-door contact by emergency responders. By registering with the City of Santa Monica for SMAlerts, you will receive emergency updates via phone, email or text message to assist with evacuations within the City.
Learn more about preparing for other Santa Monica hazards here.