A massive 7.8 earthquake struck a short time ago in the Pacific, which triggered various tsunami alerts. Fortunately for U.S. coastlines, there does not appear to be a tsunami threat at this time.

The epicenter of today’s powerful 7.8 earthquake is off the coast of Russia near where another massive 7.3 earthquake struck just weeks ago on July 29 triggering Tsunami Warnings for Hawaii and the entire U.S. mainland West Coast.  According to USGS, the earthquake struck at 8:58 am Hawaii Time from a depth of 19.5 km. Since then, more than a dozen after shocks with a magnitude greater than 4.5 have struck the area. The earthquakes are striking the east coast of Kamchatka, Russia near  the village of Petropavlovsk. Damage is likely and injuries are possible there, but there have been no confirmed reports from the epicenter region yet.

Numerous tsunami related bulletins were issued in the moments after the earthquake to Hawaii, the U.S. West Coast, and portions of the Alaskan coastline. A Tsunami Advisory had been issued for the Aleutian Islands but has since been canceled. The National Weather Service’s Tsunami Warning Center says there is no threat to the U.S. by tsunami at this time.

In Hawaii, which saw a Tsunami Warning from the weaker earthquake in July, authorities are communicating with the public that the coast is clear of tsunami threat. On the Big Island of Hawaii, Hawaii County Civil Defense released an alert informing people there that there is no threat of tsunami to the island. The Hawaii Emergency Management Agency initially went on X and wrote, “A TSUNAMI THREAT EXISTS FOR PARTS OF THE PACIFIC LOCATED CLOSER TO THE EARTHQUAKE. IF THERE IS A TSUNAMI THREAT TO HAWAII. THE EARLIEST ESTIMATED TIME THE HAZARD MIGHT BEGIN IS 0251 PM HST THU 18 SEP 2025.” However, they have since released an updated statement confirming there is now no threat of tsunami to the Aloha State.

Similar bulletins stressing there was no threat were issued for the U.S. West Coast. At 2:06 pm PT, the west coast was given a bulletin from the National Tsunami Warning Centerthat “No tsunami danger exists for the U.S. west coast, British Columbia and Alaska.

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel towards land, they build up to higher and higher heights as the depth of the ocean decreases. The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves.

A tsunami is a series of waves. The time between wave crests can vary from 5 minutes to an hour. The hazard may persist for many hours or longer after the initial wave. Impacts can vary significantly from one section of coast to the next due to local bathymetry and the shape and elevation of the shoreline. Impacts can also vary depending upon the state of the tide at the time of the maximum tsunami waves.