Two moderate earthquakes struck off Japan’s northeastern coast today, the U.S. Geological Survey said — a magnitude 5.5 tremor about 39 miles east of Onagawa Chō and a magnitude 5.0 quake roughly 38 miles east of Tomioka.
No immediate reports of damage or tsunami warnings were issued in connection with either event.
Japan Earthquakes: Where were the epicenters of the earthquakes today?
The epicenters were about 82 miles apart, with the Onagawa quake occurring around 235 miles northeast of Tokyo and the Tomioka quake about 154 miles from the capital. The closest large city to the Onagawa quake is Ishinomaki, with a population of about 140,000, located in Miyagi Prefecture.
Associated Press
Japan’s Earthquake Activity
According to earthquaketrack.com, Japan has had a total of seven earthquakes in the past week, 38 in the past month and 634 over the past year. Friday’s magnitude 5.5 was the strongest across Japn in the past week. Earlier this month, a magnitude 5.9 struck near Yonakuni in Okinawa, while the strongest this year was a magnitude 6.8 off Hokkaido’s Kuril Islands region.
Japan sits along the seismically active “Ring of Fire” and experiences hundreds of earthquakes each year, though most cause little or no damage thanks to strict building codes and extensive disaster preparedness measures. The country has endured some of the world’s most devastating quakes, including the magnitude 9.0 disaster in 2011 that triggered a tsunami and nuclear crisis in Fukushima. Authorities closely monitor seismic activity, and Japan’s early warning systems are considered among the most advanced globally.
Last month, a massive magnitude 8.8 earthquake struck off Russia’s Kamchatka Peninsula on Wednesday, triggering Pacific-wide tsunami warnings and sparking evacuations along coastal areas. Waves as high as 13 feet hit parts of Russia’s far east, and alerts extended to Japan, the United States, Chile and New Zealand. More than 1,400 aftershocks, including one of magnitude 6.9, followed the quake, raising concerns of continued seismic activity. Despite its strength, officials reported limited damage.
What was the longest earthquake ever recorded?
On December 26, 2004, a massive undersea earthquake measuring between magnitude 9.1 and 9.3 struck off the coast of Sumatra, Indonesia, rupturing for nearly 10 minutes in what scientists called the longest quake ever recorded. The tremor unleashed a devastating tsunami across the Indian Ocean that killed an estimated 227,000 people in 14 countries, from Indonesia and Sri Lanka to Thailand and Somalia.
Entire coastal communities were washed away, making it one of the deadliest natural disasters in modern history. The quake’s extraordinary duration and destructive waves prompted a global humanitarian response and spurred efforts to expand tsunami warning systems worldwide.
Update: 8/29/25, 1:58 p.m. ET: This article was updated with new information.
Update: 8/29/25, 5:39 p.m. ET: This article was updated with new information.
