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Mechanical Implications of Creep and Partial Coupling on the World's Fastest Slipping Low-Angle Normal Fault in Southeastern Papua New Guinea

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posted on 2025-05-18, 22:10 authored by J Biemiller, Carolyn BoultonCarolyn Boulton, L Wallace, S Ellis, Timothy LittleTimothy Little, M Mizera, A Niemeijer, L Lavier
We use densely spaced campaign GPS observations and laboratory friction experiments on fault rocks from one of the world's most rapidly slipping low-angle normal faults, the Mai'iu fault in Papua New Guinea, to investigate the nature of interseismic deformation on active low-angle normal faults. GPS velocities reveal 8.3 ± 1.2 mm/year of horizontal extension across the Mai'iu fault, and are fit well by dislocation models with shallow fault locking (above 2 km depth), or by deeper locking (from ~5–16 km depth) together with shallower creep. Laboratory friction experiments show that gouges from the shallowest portion of the fault zone are predominantly weak and velocity-strengthening, while fault rocks deformed at greater depths are stronger and velocity-weakening. Evaluating the geodetic and friction results together with geophysical and microstructural evidence for mixed-mode seismic and aseismic slip at depth, we find that the Mai'iu fault is most likely strongly locked at depths of ~5–16 km and creeping updip and downdip of this region. Our results suggest that the Mai'iu fault and other active low-angle normal faults can slip in large (Mw > 7) earthquakes despite near-surface interseismic creep on frictionally stable clay-rich gouges.

History

Preferred citation

Biemiller, J., Boulton, C., Wallace, L., Ellis, S., Little, T., Mizera, M., Niemeijer, A. & Lavier, L. (2020). Mechanical Implications of Creep and Partial Coupling on the World's Fastest Slipping Low-Angle Normal Fault in Southeastern Papua New Guinea. Journal of Geophysical Research: Solid Earth, 125(10). https://doi.org/10.1029/2020JB020117

Journal title

Journal of Geophysical Research: Solid Earth

Volume

125

Issue

10

Publication date

2020-10-01

Publisher

American Geophysical Union (AGU)

Publication status

Published

Online publication date

2020-10-09

ISSN

2169-9313

eISSN

2169-9356

Article number

ARTN e2020JB020117

Language

en