The 1992 Nicaragua earthquake and tsunami had a moment magnitude of 7.7.
The earthquake struck offshore on September 1, 1992, at about 6:16 p.m. local time. It occurred where the Cocos Plate is subducting beneath the Caribbean Plate along the Middle America Trench. The quake generated a destructive tsunami that affected Nicaragua’s Pacific coast and parts of Costa Rica, killing at least 116 people.
This event is especially notable because it was a “tsunami earthquake.” Its initial surface-wave magnitude was only about 7.0–7.2, but longer-period analyses produced a moment magnitude around 7.6–7.7. The rupture was unusually slow and shallow, allowing substantial movement near the trench and producing a tsunami much larger than its first seismic measurements suggested.
The waves reached run-up heights of up to about 9.9 meters, with average heights commonly reported between 3 and 8 meters. A frequent mistake is to treat every magnitude figure as contradictory: the values refer to different measurement methods, while 7.7 is the standard moment-magnitude figure used for the event.