The sequence
Newest first.
- 4.4south of the Fiji Islands48 km SSW of the mainshock1 week ago· 593.7 km deep
- 4.3south of the Fiji Islands44 km S of the mainshock1 week ago· 599.1 km deep
- 4.6south of the Fiji Islands31 km SSW of the mainshock1 week ago· 587.4 km deep
- 4.7South of Fiji islands40 km S of the mainshock1 week ago· 577.4 km deep
- 4.3south of the Fiji Islands37 km SW of the mainshock3 weeks ago· 591.1 km deep
- 4.5Fiji region39 km WSW of the mainshock3 weeks ago· 602.2 km deep
How the rupture zone is measured
An aftershock is a smaller earthquake triggered as the crust settles around the fault that ruptured. They cluster along that rupture, so the area worth searching scales with the size of the mainshock rather than being a fixed radius.
The 50 km zone above comes from the Wells & Coppersmith (1994) rupture-length relation, doubled because aftershocks routinely extend about one rupture length beyond each end of the fault, then floored at 50 km and capped at 400 km. Anything outside it is counted as separate regional seismicity, not part of this sequence.
Aftershocks are most frequent in the hours right after the mainshock and taper off over days to months. A quiet day does not mean the sequence has ended.
Data from USGS, EMSC and partner agencies. Magnitudes and locations are preliminary and may be revised.