2018 Fiji earthquake

Initially reported as an 8.0 earthquake, it was later revised by the United States Geological Survey to an 8.2.[3] Due to the earthquake being a deep-focus event, no damage was reported but it was widely felt. Small "tsunami" waves were also spotted along the coast, although it was too deep to generate any negligible tsunami.[4][5] More than 250 aftershocks were seen 34 days after the main event. Focal mechanism suggested that the earthquake had a complex rupture process and fast rupture velocity of 4.1 km/s. Rupture was observed along multiple faults in a mainly north northeast striking plane for a suggested length of 102 to 152 km.[6]

A cross-section diagram showing the Pacific slab under the Fijian Islands and the epicenters for both earthquakes.

Eighteen days after the 8.2 event, another earthquake struck closer to the island of Viti Levu. The M_ww 7.9 earthquake was a downgrade from an initial magnitude of 8.1.[7][8] The earthquake had a complex combination of strike-slip and dip-slip during rupture within the slab. It was an unusual event the portion of the slab is rather aseismic. The depth of this event was slightly deeper than the first quake, and the rupture velocity was much slower, at 2.5 km/s.[6] It was suggested that coulomb stress transfer from the 8.2 quake may have triggered the 7.9 earthquake however, stress from the first quake was not sufficient to generate the next event alone. The M_ww 7.9 event may have been dynamically triggered by the M_ww 8.2 quake but the 18-day interval period was longer than usual as triggered quakes usually nucleate within a few hours to days.[6]