What to Know
- About 5 million Californians were under a brief tsunami warning after a magnitude-7.0 offshore earthquake.
- Shaking was reported on the Northern California and Oregon coasts and in parts of the Bay Area.
- The warning, indicating the possibility of destructive flooding and strong currents, expired later Thursday morning.
- The California Geological Survey says the California's shores have been struck by more than 150 tsunamis since 1800.
A powerful magnitude-7.0 offshore earthquake in Northern California led to a brief tsunami warning Thursday morning for about 5 million people on the West Coast.
A tsunami, a word that comes from the Japanese characters for harbor and wave, is a series of long waves that are often, but not always, caused by undersea earthquakes. The sudden displacement of ocean water can lead to devastation if the wave reach land, making tsunamis some of the most powerful and destructive natural forces on Earth.
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Most of the tsunamis observed in California have been small, causing a slight rise in water levels in coastal areas and little damage.
But whether they're generated by local or distant sources, such as earthquakes in the Alaska Subduction Zone or just off the coast, tsunamis have led to deaths and destruction in the state's waterfront communities, some of which were evacuated Thursday due to the tsunami warning and fears of possible flooding and strong currents.
There were no reports of significant damage or flooding associated with Thursday's undersea quake.
The California Geological Survey says the California's shores have been struck by more than 150 tsunamis since 1800. Below, a look at some of the state's more significant tsunamis.
Jan. 26, 1700: Northern California tsunami
There are no written records, but scientists have reconstructed the event using geologic evidence, oral histories and Japanese documents that describe waves along that country's coast later in the day. A strong quake along the Cascadia Subduction Zone, which stretches from Cape Mendocino to Vancouver Island, British Columbia, likely generated a 50-foot tsunami in Northern California.
Dec. 21, 1812: Santa Barbara tsunami
Low lying areas of Santa Barbara and Ventura were flooded and damage was reported to nearby ships due to powerful waves. Researchers have theorized that a landslide triggered by an earthquake caused the tsunami.
April 1, 1946: Central Coast tsunami
A magnitude-8.6 quake in the Alaska Subduction Zone generated this tsunami, which caused flooding about 1,000 feet inland in Half Moon Bay on California's Central Coast. Damage was estimated at more than $150,000. One fatality was reported in California.
May 22, 1960: : Magnitude-9.5 Chile earthquake and tsunami
In a staggering example of nature's power, a magnitude-9.5 earthquake -- the strongest ever recorded -- off the coast of Chile produced tsunami waves that traveled across the Pacific Ocean in a northwest direction. The tsunami resulted in 61 deaths in Hawaii and 138 deaths in Japan. In California, the waves damaged harbor on the coast and inundated waterfront areas in Crescent City.
March 28, 1964: Deadly Alaska quake causes West Coast tsunami
The West Coast's most devastating tsunami on record was generated by a deadly magnitude-9.2 quake off Alaska. It caused powerful waves that slammed coastal areas, including the Northern California community of Crescent City, where 11 people were killed. A surge about 20-feet high flooded nearly 30 city blocks, according to the Department of Conservation. A total of more than 100 people in the tsunami zone, from Alaska and down the Pacific coasts of Canada and the United States, were killed.
April 25, 1992: Cape Mendocino earthquake and tsunami
The magnitude-7.2 Cape Mendocino earthquake off the coast of Humboldt County caused shaking throughout the region. Like Thursday's quake, the center was in one of California's most geologically complex and seismically active areas. The quake caused a small tsunami that arrived on the coast about 20 minutes later. Waves were recorded on tide gauges on the Oregon and California coasts. A small wave was even detected in Hawaii.
Nov. 15, 2006: Kuril Islands earthquake
Again, Crescent City bore the brunt of tsunami damage in California following a magnitude-8.3 earthquake in the Kuril Islands in the northwest Pacific Ocean. Damage was estimated at about $20 million from a tsunami that caused strong currents.
March 11, 2011: Japan earthquake produces strong currents in California
Although not nearly as destructive as the 1964 tsunami, a magnitude-9.0 earthquake in the Tohoku region of Japan led strong tsunami currents that damaged harbors along California's coast. One death was reported in connection with the tsunami. The worst damage was in Crescent City and Santa Cruz.
Jan. 15, 2022: Tonga volcano collapse and tsunami
The eruption of Tonga's Hunga Tonga-Hunga Ha'apai volcano produced the largest explosion ever recorded by modern scientific instruments. The energy released was so strong, it produced tsunami flooding on California's coast, strong currents and an estimated $8 million to $10 million in damage, including in parts of Santa Cruz and Ventura.
