A powerful earthquake struck the coast of northern Japan on Monday, triggering short-term tsunami warnings that have since been lifted. As of 12:29 p.m. local time on April 20, Japan is at a slightly elevated risk of experiencing a megaquake over the next week, according to the Japan Meteorological Agency (JMA).
Monday’s earthquake occurred on April 20, 2026 off the coast of Sanriku, Iwate Prefecture at a depth of 10 kilometers (around 6.21 miles), at 4:53 p.m. local time, per the JMA. The earthquake was a magnitude 7.7 on the Richter scale, with an intensity of upper 5 on the Japanese scale of 0 to 7 in the hardest-hit areas.
According to the Pacific Tsunami Warning Center‘s latest tsunami warning for Japan, “based on all available data… the tsunami threat from this earthquake has now passed.” The advisory was initially issued for Japan’s Iwate Prefecture, Hokkaido, Aomori, Miyagi, and Fukushima Prefectures.
In a press briefing following Monday’s earthquake, Prime Minister Sanae Takaichi informed reporters that authorities are doing their “utmost to assess the damage, implement emergency disaster response measures such as search and rescue operations, and provide timely and accurate information to the public,” per the Associated Press. “At this time, we are still confirming the extent of human and material damage, but we will receive detailed reports shortly and proceed with disaster response efforts,” the prime minister added.
Japan issue megaquake advisory
During the April 20 news conference, Japan’s Meteorological Agency reported that there is a 1% chance that a megaquake could take place in northern Japan in the next week following Monday’s earthquake. The alert applies to 182 cities and towns from Hokkaido to Chiba, NHK reports. No evacuation orders are currently in place for the affected areas.
While not a precise scientific designation, a megaquake is generally considered a large seismic event placed at an eight or higher on the Richter scale that ruptures along major faults and can trigger further events like tsunamis. The typical regional risk of a megaquake is placed at 0.1%, meaning the likelihood of the event has increased tenfold. Officials clarified that the announcement was not a prediction and encouraged residents to resume their daily lives with increased preparedness measures, such as assembling emergency food supplies and go bags.
What travelers should know
As of April 20, the US travel advisory for Japan places the country at a level one, which states that travelers should “exercise normal precautions.” The US embassy in Japan reminds travelers that when a tsunami alert is issued, they should stay out of the water and away from beaches and waterways, follow instructions from local officials, and follow evacuation orders by local government until all advisories are lifted.
The country’s Nuclear Regulation Authority said there were no reports of abnormalities at key coastal nuclear plants at the time of writing, but assessments are ongoing, per the AP.
US citizens can “stay updated through official sources such as NOAA Weather Radio, Coast Guard emergency frequencies, Japan Meteorological Agency, and local news,” the Japanese embassy advises. The US State Department also recommends enrolling in the Smart Traveler Enrollment Program (STEP) to receive information and alerts and make it easier to locate you in an emergency overseas.
A version of this article was originally published on Condé Nast Traveller UK. This is a developing news story and will be updated with information. Additional reporting by Kat Chen.
