Distribution of slip at the northern Sumatran fault system

J. F. Genrich, Y. Bock, R. McCaffrey, L. Prawirodirdjo, C. W. Stevens, S. S O Puntodewo, C. Subarya, Shimon Wdowinski

Research output: Contribution to journalArticle

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Abstract

We model spatial variations in horizontal displacements of 117 geodetic sites measured during annual surveys in 1989-1996 with the Global Positioning System (GPS) as elastic strain across a locked strike-slip fault to infer the contemporary slip rate, locking depth, and location of the Sumatran fault (SF) in northern Sumatra (1° S-3° N). GPS-derived slip rate estimates increase slightly northward from 23±3 mm/yr at 0.8° S to 26±2 mm/yr at 2.7° N. They agree with geologic estimates north of the equator, but at 0.5° S they are ∼ 10 mm/yr higher. Strain appears to be distributed asymmetrically about the fault. South of 2° N, about 5 mm/yr of shear is required within the offshore forearc, west of the fault, to achieve a closer agreement of fault locations inferred from GPS velocities with geologically identified traces of the SF. Locking depth estimates are of the order of 10-20 km. The western branch of the major fault bifurcation near 1° N slips at a rate 5 times higher than the eastern branch. The two main strands of the fault at the northwestern tip of Sumatra (5.5° N) appear to be nearly free of horizontal strain; significant slip must occur away from the two strands, probably farther east at two other geologically active branches. The Banda Aceh embayment is extruded to the northwest at a rate of 5±2 mm/yr. Within the estimated velocity uncertainties of several millimeters per year, fault-normal deformation along the SF is insignificant. Almost strain free, the northern part of the back arc basin is part of the rigid Sunda Shelf, while the northern forearc is subjected to 8±5 × 10-8yr-1 of extension nearly parallel to the arc.

Original languageEnglish (US)
Article number2000JB900158
Pages (from-to)28327-28341
Number of pages15
JournalJournal of Geophysical Research C: Oceans
Volume105
Issue numberB12
StatePublished - Dec 10 2000
Externally publishedYes

Fingerprint

slip
Global Positioning System
Global positioning system
strands
Strike-slip faults
locking
estimates
arcs
Electric fault location
GPS
slip rate
equators
shelves
distribution
shear
bifurcation
strike-slip fault
normal fault
spatial variation
basin

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

Genrich, J. F., Bock, Y., McCaffrey, R., Prawirodirdjo, L., Stevens, C. W., Puntodewo, S. S. O., ... Wdowinski, S. (2000). Distribution of slip at the northern Sumatran fault system. Journal of Geophysical Research C: Oceans, 105(B12), 28327-28341. [2000JB900158].

Distribution of slip at the northern Sumatran fault system. / Genrich, J. F.; Bock, Y.; McCaffrey, R.; Prawirodirdjo, L.; Stevens, C. W.; Puntodewo, S. S O; Subarya, C.; Wdowinski, Shimon.

In: Journal of Geophysical Research C: Oceans, Vol. 105, No. B12, 2000JB900158, 10.12.2000, p. 28327-28341.

Research output: Contribution to journalArticle

Genrich, JF, Bock, Y, McCaffrey, R, Prawirodirdjo, L, Stevens, CW, Puntodewo, SSO, Subarya, C & Wdowinski, S 2000, 'Distribution of slip at the northern Sumatran fault system', Journal of Geophysical Research C: Oceans, vol. 105, no. B12, 2000JB900158, pp. 28327-28341.
Genrich JF, Bock Y, McCaffrey R, Prawirodirdjo L, Stevens CW, Puntodewo SSO et al. Distribution of slip at the northern Sumatran fault system. Journal of Geophysical Research C: Oceans. 2000 Dec 10;105(B12):28327-28341. 2000JB900158.
Genrich, J. F. ; Bock, Y. ; McCaffrey, R. ; Prawirodirdjo, L. ; Stevens, C. W. ; Puntodewo, S. S O ; Subarya, C. ; Wdowinski, Shimon. / Distribution of slip at the northern Sumatran fault system. In: Journal of Geophysical Research C: Oceans. 2000 ; Vol. 105, No. B12. pp. 28327-28341.
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