Is there an upper limit to normal fault slip rates? The Mai’iu fault, located within the rapidly extending Woodlark Rift, Papua New Guinea, is one of few active continental low-angle normal faults (LANFs) globally. There is ongoing debate regarding how commonly normal faults slip at shallow (<30°) dips, and at what rates. We present a global compilation of reported slip rates on active and inactive extensional detachments that suggests that such faults may slip at >10–20 mm/yr—faster than any reported high-angle normal fault. Cosmogenic nuclide exposure dating (10Be in quartz) of the lowermost Mai’iu fault scarp supports this finding, indicating slip at 11.7 ± 3.5 mm/yr over the past ∼5.5 k.y. Our results highlight the long-term viability of LANFs, and show that the Mai’iu fault represents one of Earth’s fastest active continental normal faults. Rapid and large-displacement slip is likely enabled by extremely low fault frictional strength.

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