A powerful magnitude 8.8 earthquake east of Russia’s Petropavlovsk-Kamchatsky triggered tsunami advisories for the California, Oregon, and Washington coasts.
The July 29 earthquake off the coast of Russia was the largest in the world since the 2011 magnitude 9 earthquake in Tohoku, Japan. According to the U.S. Geological Survey, at the location of this earthquake, the denser Pacific plate is slipping under the lighter North America plate at a velocity of 80 millimeters per year—making it one of the fastest areas in the world where two tectonic plates are colliding.
San Luis Obispo County, which went on tsunami advisory as soon as the earthquake occurred, experienced relatively little impact.
“One of our concerns was Port San Luis, and they didn’t report any damage,” SLO County Office of Emergency Services coordinator Scott Milner said. “The main concern is abnormal currents. They don’t want people to be dragged around on water.”
Emergency officials had advised residents and the public in coastal areas to stay away from beaches, shorelines, ports and harbors; to not go to the beach to see waves; to avoid entering the water for any reason; and to remain alert for any sudden changes in sea level or strong, unexpected currents.
The county prepared for a tsunami with a potential wave height of 1.7 to 3.2 feet that could have hit around 12:30 a.m. on July 30. SLO County Fire had issued an evacuation warning for parts of Los Osos, but Milner confirmed that no one had to vacate the premises.
He told New Times that wave activity was only slight.
“We didn’t close the beaches because we were never put on a tsunami warning, which is the next level,” he said. “They’re monitoring the tidal gauges and buoys.”
Milner added that Port San Luis experienced sea surface elevation of 1.5 feet above its normal expected tidal level. The maximum recorded elevation at Port San Luis took place at 2:14 a.m. when the sea surface level rose to 2.7 feet.
For a tsunami advisory to be lifted, the sea surface elevation must drop below 1 foot and should stay that way for at least three hours, Milner said. The tsunami advisory was lifted for SLO County around 1:30 p.m. on July 30.
The advisory was still in place for Santa Barbara County, as of 2 p.m. July 30, because that area is farther south than SLO, Milner said.
Stay up to date on the advisory and preparedness by checking ReadySLO.org and prepareslo.org/en/tsunami.aspx. Community members can also check the county Instagram page @countyofslo and the Office of Emergency Services X feed @slocountyoes.
“It’s been over 10 years since we last had a tsunami advisory, so it’s been quite a while,” he said. Δ
This article appears in Jul 31 – Aug 10, 2025.