Attention Southern California: Here's Why A Tsunami Advisory Was Issued Saturday

A tsunami advisory was issued Saturday morning due to a massive undersea volcano explosion in the South Pacific that sent waves rolling east toward the U.S. West Coast.
The U.S. National Tsunami Warning Center says we should be prepared for higher water in bays and harbors. Waves due to the tsunami were expected to peak in Southern California between 7:30-8 a.m. Saturday morning. But the effects of the tsunami are longer lasting. Meteorologists and seismologists warned that the waters near shore are likely hazardous.
As Lucy Jones, a noted seismologist, said to her followers on Twitter: "Moving water has huge momentum."
This is a classic demonstration of how tsunamis will slosh water in and out of harbors as a result of the broad waves that pile in and back out for hours following the first surge. #tsunami https://t.co/SvJHPtgDNw
— NWS Los Angeles (@NWSLosAngeles) January 15, 2022
Orange County alerted people by cell phone in the morning and again after noon that all beaches — from Seal Beach to San Clemente — there have been closed. The Orange County sheriff took that step as a precaution. City police departments in the O.C. closed their piers.
Beaches in San Diego County were also closed.
Beach web cams and eyewitnesses indicated that the waves hitting beaches here did not seem extraordinary.
Further up the coast, Port San Luis reported flooding that reached parking lot. The south facing beach is just north of Pismo. The National Weather Service said tide gauges there indicated some of the highest tsunami waves recorded on the West Coast.
Measured sea-level reached 8.1-feet at the Port San Luis Tide Gauge at 8:24 a.m. due to the Tonga volcano eruption that generated a tsunami. This is the highest sea-level measurement since the Jan. 27, 1983 storm that produced a sea-level measurement of 8-feet at Port San Luis. pic.twitter.com/5V2D9OAXaX
— John Lindsey (@PGE_John) January 15, 2022
Here is an updated statement on the Tsunami Advisory currently in effect for the coast. Max wave heights reported from Port San Luis. #SoCal #CAwx #CentralCoasthttps://t.co/eX1ZgOW6QG pic.twitter.com/BTXRVdLxSZ
— NWS Los Angeles (@NWSLosAngeles) January 15, 2022
The Origin
The surge was generated by a huge explosion of an undersea volcano near the South Pacific island nation of Tonga on Friday.
The coast of the main island in Tonga was swamped by a surge of water and falling ash. The initial explosion was captured by a satellite camera.
1.14.2022: (correction on date) Large volcanic eruption near Tonga (Hunga Tonga-Hunga Ha'apai volcano) today as seen from outer space. Shown on visible imagery using the Himawari satellite. #hiwx #tsunami #earthquake pic.twitter.com/Y18W7wvXl9
— NWSHonolulu (@NWSHonolulu) January 15, 2022
Why You Should Be Careful
The National Weather Service is urging caution, since rip tides are likely even if massive waves are not.
"A tsunami capable of producing strong currents hazardous to swimmers, boats, and coastal structures is expected," the NWS office is L.A. tweeted this morning.
Seismologist Lucy Jones had these reminders:
With a tsunami advisory in effect, some reminders about what that means:
— Dr. Lucy Jones (@DrLucyJones) January 15, 2022
1. An advisory means expect waves of 1-3 feet, so a short term increase in sea level of 1-3 ft. If you are more than 3 feet above sea level it will not affect you. This is only an issue near the beach
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2. Tsunamis are not one wave. It's more like sloshing and that sloshing can continue for a day. Just because the first wave has passed, it is not time to go see the beach.
— Dr. Lucy Jones (@DrLucyJones) January 15, 2022
3. Much tsunami damage happens in ports because of the currents. Moving water has huge momentum.
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Here's a guide to warning levels:
Here are the different alerts issued by the National Tsunami Warning Center. More at https://t.co/h1CR82bF8o. #tsunami pic.twitter.com/EaAlz3HlHN
— NWS Los Angeles (@NWSLosAngeles) January 15, 2022
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