The Philippine Institute of Volcanology and Seismology (Phivolcs) has assured the public that a powerful magnitude 7.4 earthquake which struck off the east coast of Honshu, Japan, on Monday poses no tsunami threat to the Philippines.
The earthquake occurred at 3:52 pm Philippine time on 20th April 2026. Phivolcs said that while hazardous tsunami waves are possible for coastal areas within 300 kilometres of the epicentre, the Philippines is not among those at risk. The advisory was issued for information purposes only and no action is required from the public.
Japan’s Meteorological Agency (JMA) reported the quake as magnitude 7.5 and issued a tsunami warning for waves of up to three metres. The tremor struck in Pacific waters off northern Iwate prefecture and was strong enough to shake large buildings as far as Tokyo, hundreds of kilometres away. Around 40 minutes after the quake, an 80 centimetre tsunami wave hit a port in Kuji in Iwate.
“Evacuate immediately from coastal regions and riverside areas to a safer place such as high ground or an evacuation building,” the agency said, warning that tsunami damage was expected. “Tsunami waves are expected to hit repeatedly. Do not leave safe ground until the warning is lifted.”
Footage from national broadcaster NHK did not show any immediate visible damage around several ports in Iwate. A JMA official warned in a televised press briefing that more quakes could strike the area.
Prime Minister Sanae Takaichi urged residents in affected areas to move to higher ground, adding that the government was working to confirm whether there were any casualties or property damage. The prime minister’s office said it had set up a crisis management team.
Japan sits atop four major tectonic plates along the western edge of the Pacific Ring of Fire. The country typically experiences around 1,500 seismic jolts a year and accounts for about 18% of the world’s earthquakes.
Japan remains haunted by the memory of a 9.0 magnitude undersea quake in 2011 that triggered a tsunami killing around 18,500 people and causing a devastating meltdown at the Fukushima nuclear plant.
In 2024, the JMA issued its first special advisory of a possible megaquake along the Nankai Trough, an 800 kilometre undersea trench where the Philippine Sea tectonic plate is slowly slipping underneath the continental plate that Japan sits atop. The government has said a quake along the trough and subsequent tsunami could kill as many as 298,000 people and cause up to two trillion dollars in damage. The 2024 advisory, which was lifted after a week, triggered panic buying of staples and led holidaymakers to cancel hotel reservations.
A second megaquake advisory lasting one week was issued in December 2025 following a magnitude 7.5 tremor off the northern coast. The December tremor produced tsunami waves of up to 70 centimetres and injured more than 40 people, though no major damage was reported.
Phivolcs, which routinely monitors distant earthquakes to assess potential impact on Philippine shores, defined a tsunami in its advisory as a series of sea waves commonly generated by undersea earthquakes, capable of reaching heights of more than five metres. It noted that tsunamis are often incorrectly referred to as tidal waves and are sometimes confused with storm surges.
About the Author
