Tectonic Hotspots: the Week's Most Powerful Earthquakes Ranked

A magnitude 6.0 earthquake struck 12 km west of Anacapri, Capri, on 6 March 2026, a stark reminder that Italy's idyllic coastlines sit above one of Europe's most volatile tectonic zones. This event is 3.5% less powerful than the #1 Vallenar quake but represents a significant risk given the Campanian volcanic arc's history of major eruptions. Thirteen people reported feeling it; the USGS estimated a maximum instrumental intensity of 3 on the modified Mercalli scale, with the 10 km depth attenuating shaking better than Japan's shallow #3 earthquake at 4.2 km.

A magnitude 5.9 earthquake struck 21 km northeast of Otobe, Hokkaido, on 5 March 2026, occurring at a notably shallow depth of just 4.2 km. This depth made it 58% shallower than the #4 Kamchatka quake, maximizing local shaking despite its moderate magnitude. Japan experiences roughly 1,500 felt earthquakes annually due to its position above four tectonic plates, with southern Hokkaido sitting where the Pacific Plate subducts at 9 cm/year. No casualties were reported, thanks to strict building codes.

A magnitude 5.9 earthquake struck 160 km south-southeast of Vilyuchinsk, Kamchatka, on 4 March 2026, at 10 km depth. This event matches the #3 Otobe quake in magnitude but occurred in a remote location with no felt reports, highlighting the extreme seismic activity of a peninsula that has produced the magnitude 9.0 1952 Kamchatka earthquake. Kamchatka sits above the Pacific and North American plate convergence, making it one of the most seismically intense landmasses on Earth. Geologically significant, it's a reminder that the region is never truly at rest.

A magnitude 5.9 earthquake struck 15 km west-southwest of the Tongan island of Niuatoputapu on 4 March 2026, tied as the strongest event this week. Tonga sits at the western edge of the Pacific Plate, where it subducts beneath the Australian Plate at the Tonga Trench — one of the deepest ocean trenches on Earth and one of the most seismically active subduction zones. Eight people reported feeling this event; the shallow 12 km depth produced an estimated instrumental intensity of only 4, suggesting the shaking was moderate rather than damaging. This magnitude is 0.4 units lower than the 6.3 Mw event that struck the same region in 2022.

At magnitude 5.7, the Attu Station earthquake on 2 March 2026 is only 0.2 units weaker than the #5-ranked Tonga event but triggered a tsunami advisory due to its submarine setting. The Aleutian Islands extend in a 1,900 km arc from Alaska to Kamchatka and form one of the most active subduction zones on Earth. At 10 km depth, any M5.5+ submarine earthquake here automatically triggers an assessment protocol. The single felt report came from a remote monitoring station; the nearest population centre is hundreds of kilometres away. This event is 0.5 magnitude points smaller than the typical M6.2 that triggers a warning.

A magnitude 5.7 earthquake struck 110 km east of Yamada in Iwate Prefecture on 4 March 2026, near the offshore area devastated by the 2011 Tohoku earthquake and tsunami. The Sanriku Coast of northeastern Honshu sits above the Japan Trench — a subduction zone that produced the catastrophic 2011 event (9.0) and continues to generate aftershocks and new earthquakes more than fifteen years later. With a relatively shallow depth of 10 km, this event could in principle generate localised strong shaking, though the USGS green alert indicated no significant impact expected for a 5.7 magnitude at this depth. This is 3.3 magnitude units weaker than the 9.0 Tohoku quake.

A magnitude 5.5 earthquake struck 2 km south-southeast of Rodotopi in northwestern Greece on 4 March 2026 — the same event that topped the month's significance rankings due to its yellow USGS alert status and 25 felt reports. Shallow at 10 km depth, the event generated an estimated maximum instrumental intensity of nearly 7 — enough for strong shaking to be felt across a wide area of Epirus and Albanian border regions. Greece has been struck by catastrophic earthquakes throughout its recorded history, from the 1953 Ionian Islands earthquake that killed 455 people to the 1999 Athens earthquake that killed 143. This intensity is one point higher than the M5.5 event in Japan at rank #7.

The M 5.5 earthquake south of the Kermadec Islands on 7 March 2026 is the week's ninth strongest tremor, yet it releases less than 15% of the energy of the #1 quake. This event is a routine reminder that the Kermadec Trench, the second deepest oceanic trench on Earth at 10,047 meters, generates numerous earthquakes each year due to intense subduction activity. In fact, the Kermadec arc is faster than the average subduction zone, with convergence rates exceeding 60 mm annually. While no nearby population felt the shaking, the quake contributes significantly to the planet's total seismic energy, and scientists monitor it closely for tsunami potential—unlike smaller events, this magnitude can trigger local waves.

This M 5.4 earthquake, striking 109 km east of Yamada, Japan, is the weakest on the list but occurred just 511 seconds before the #9 event, revealing a tightly linked aftershock sequence. Both quakes ruptured within minutes of each other in the Japan Trench, where the 2011 megathrust still releases strain—this pair alone released energy equivalent to 0.8% of the mainshock. The event is shallower than the typical aftershock in this region, at a depth of 25 km, and falls within the ongoing seismic swarm that has produced over 30 events above M 4.0 this year. Such sequences are common in this subduction zone, where accumulated stress continues to be released years later.