Event facts
Estimated shaking · MMI X
Extreme. Few structures remain standing. Bridges destroyed, ground waves visible. Underground pipes broken.
MMI is the Modified Mercalli Intensity scale — what people actually feel. This estimate is derived from magnitude alone; real shaking varies with depth, distance and local soil. The official USGS ShakeMap is the authoritative source.
What an M7.7 feels like
Major earthquake. Felt for hundreds of kilometres. Anyone outdoors will be thrown to the ground; difficult to remain standing.
Heavy damage to most buildings, complete collapse of poorly-built structures. Bridges, roads and underground utilities affected.
What a intermediate depth means
Intermediate-depth events (70–300 km) attenuate more before reaching the surface, so a given magnitude is typically felt over a wider but weaker area than a shallow quake of the same size.
Energy released
This earthquake released roughly 2.24e+16 joules of seismic energy — about 355.35× the Hiroshima atomic bomb.
Caveat: bomb energy is concentrated at a single point in microseconds; seismic energy radiates outward through Earth's crust over many seconds. The comparison is for relative scale only.