Real-time coverage of earthquake event — 212 km E of Onagawa Chō, Japan — Pandita Data.
🌍 OPEN LIVE 3D EARTHQUAKE MAPA magnitude 5.6 earthquake struck 212 kilometers east of Onagawa Chō, Japan at 19:21 UTC on August 26, 2026, at a shallow depth of 10 kilometers. The USGS issued no tsunami warning and assigned a GREEN PAGER alert, indicating minimal expected casualties and negligible economic damage. The event occurred within Japan's hyperactive Pacific Ring of Fire, where the Pacific Plate descends beneath the North American Plate at rates of 8–9 centimeters per year.
This shallow rupture—occurring at just 10 km depth—released seismic energy typical of subduction zone megathrust adjustment. Though moderate in magnitude, shallow earthquakes transmit energy more efficiently to the surface, making them felt across wider areas than deeper events of equivalent magnitude. Only 1 person reported feeling this quake, consistent with its offshore location and moderate size. The event poses no regional tsunami risk due to its modest energy release and predominantly strike-slip rupture mechanism rather than vertical seafloor displacement.
Japan's earthquake activity stems from the collision of four major plates: the Pacific, Philippine, Eurasian, and North American. The coordinates 38.129°N, 143.848°E place this event within the Japan Trench subduction system, where the Pacific Plate descends at approximately 8.5 cm/year. This region has produced some of Earth's largest recorded earthquakes, including the 2011 Tohoku M9.1 event, which occurred 200 km south of this epicenter. Shallow subduction zone earthquakes like this one represent interplate stress release as overlying plates are dragged seaward during subduction initiation.
At magnitude 5.6, this earthquake released approximately 1.1 × 1018 joules of energy—equivalent to 263 kilotons of TNT. The 10 km depth classifies it as a shallow crustal or interplate rupture, which efficiently couples plate motion and releases energy across smaller fault segments than deeper events. Shallow ruptures generate higher-frequency ground motion (4–25 Hz), which damages mid-rise buildings and resonates with structures 5–20 stories tall. However, the offshore epicenter 212 km from Onagawa Chō limited exposure to populated areas.
Shallow events (0–35 km): Couple seismic waves efficiently to surface. High frequency, sharp acceleration pulses. Greater structural damage per magnitude unit. This event: 10 km depth = efficient energy transmission, but offshore location reduces impact. Deep events (>300 km): Attenuate energy before reaching surface. Lower frequency, minimal damage.
Onagawa Chō and coastal Miyagi Prefecture lie ~212 km west of the epicenter—outside the primary damaging ground motion zone for a M5.6 event. Seismic intensity in Miyagi likely reached I–II on the Modified Mercalli Scale (weak shaking, minimal perception). The 2011 Tohoku earthquake, originating 200 km to the south, generated M9.1 energy and triggered devastating tsunami waves. This M5.6 event, with no vertical seafloor displacement recorded, poses zero tsunami risk. Japan's earthquake early warning (EEW) system detected the rupture within seconds, issuing alerts to rail networks, utilities, and emergency services—standard protocol for all seismic events >M4.5.