Tsunami Watch: What is it and why is Hawaii on watch after magnitude 8 earthquake hits Russia's Kamchatka Peninsula

A powerful magnitude 8.0 earthquake struck off Russia’s Kamchatka Peninsula on July 29, triggering a tsunami advisory in Japan and a tsunami watch for Hawaii. The quake, centered approximately 250 kilometers from Hokkaido at a depth of about 19 km (12 miles), prompted Japan’s meteorological agency to forecast waves up to one meter along its Pacific coast. Meanwhile, the Pacific Tsunami Warning Center in Honolulu issued a watch and has warned that tsunami waves may reach Hawaii as early as 7:17 p.m. HST, pending further analysis. Emergency leaders are monitoring the evolving threat closely.


Earthquake and tsunami threat:

On July 29 at roughly 23:24 UTC (1:24 p.m. HST), the U.S. Geological Survey reported a magnitude 8.0 quake approximately 52.2° N, 160° E, located off the east coast of Kamchatka Krai in Russia. With an origin depth of only about 19 km, the event is considered shallow, significantly increasing the likelihood of tsunami generation.

Why is this earthquake notable?

Its magnitude of 8.0 places it among the most powerful recorded in the region in recent decades. Its shallow depth and relatively near distance to Japan raised immediate alarm. Its potential to generate widespread tsunami effects, even in distant shores like Hawaii, was sufficient for an elevated alert status within minutes.

Japan’s Meteorological Agency issued a tsunami advisory for its Pacific coastline, especially Hokkaido through Kyushu, anticipating waves up to one meter starting around 10:00 a.m. local time in Hokkaido, and progressing southwards between 10:30 a.m. and 11:30 a.m. Authorities urged residents to stay away from beaches and coastal waters.


What is a tsunami watch?

A tsunami watch is a type of tsunami message issued by tsunami warning centers to alert emergency management officials and the public that a tsunami may later impact a specific area. Tsunami watches are normally issued based on seismic information (like an earthquake occurring in a tsunamigenic zone) without confirmation that a destructive tsunami is already underway. A tsunami watch may be upgraded to a tsunami advisory or warning, or it may be cancelled altogether, depending on updated information and analysis from the tsunami warning centers.


Here’s what to do under a tsunami watch:

Stay informed: Pay close attention to official sources of information, such as your local radio and television stations, weather radios, credible weather service websites, and local emergency management officials.

Be prepared: This includes having a household emergency plan, knowing your evacuation routes, and having a getaway kit ready.

Know your evacuation route: If you live, work, or play on the coast, you should know if you are in a tsunami hazard area and plan evacuation routes to higher ground or further inland.

It's important to remember that a tsunami watch is a precautionary measure, allowing you and emergency officials to prepare for the possibility of a tsunami.

How is it different from a tsunami warning or a tsunami advisory?

A tsunami warning is issued when a dangerous tsunami with the potential for widespread inundation is imminent or expected and requires immediate action, potentially including evacuation. A tsunami advisory is issued when a tsunami with the potential to generate strong currents or dangerous waves in or very near the water is imminent, expected, or occurring.


Why is Hawaii on watch?

Although epi-centered thousands of kilometers away, Hawaii faces a potential threat due to the quake's magnitude and ocean depth. The Pacific Tsunami Warning Center (PTWC) issued a tsunami watch at 1:33 p.m. HST, stating that a tsunami “may have been generated… that could be destructive on coastal areas even far from the epicenter.” The earliest possible arrival of waves to Hawaiian shores was 7:17 p.m. HST that same day.

Currently, PTWC analysts are investigating tsunami propagation models to determine wave height, direction, and timing. Updates are expected hourly or sooner as available data comes in.


Residents, particularly in coastal areas of Hawaii and Japan, are advised to:

Stay out of the water and off beaches,

Monitor official channels and local media for real-time updates,

Prepare to move to higher ground if a warning is declared,

Avoid low-lying waterfront properties until the watch is lifted.

At this time, no tsunami warning has been issued for Hawaii, only a watch. That means the threat is possible rather than confirmed. Authorities are cautioning patience and vigilance over panic.

Aside from Japan and Hawaii, Alaska’s Aleutian Islands, specifically areas from Samalga Pass to Attu, are under a tsunami advisory, indicating potential hazardous waves and strong currents. Alerts have also been issued for Guam, American Samoa, and other Pacific territories under evaluation.