Astypalaea Linea: A Large-Scale Strike-Slip Fault on Europa

B. Randall Tufts, Richard Greenberg, Gregory Hoppa, Paul Geissler

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Astypalaea Linea is an 810-km strike-slip fault, located near the south pole of Europa. In length, it rivals the San Andreas Fault in California, and it is the largest strike-slip fault yet known on Europa. The fault was discovered using Voyager 2 images, based upon the presence of familiar strike-slip features including linearity, pull-aparts, and possible braids, and upon the offset of multiple piercing points. Fault displacement is 42 km, right-lateral, in the southern and central parts and probably throughout. Pull-aparts present along the fault trace probably are gaps in the lithosphere bounded by vertical cracks, and which opened due to fault motion and filled with material from below. Crosscutting relationships suggest the fault to be of intermediate relative age. The fault may have initiated as a crack due to tension from combined diurnal tides and nonsynchronous rotation, according to the tectonic model of R. Greenberg et al. (1998a, Icarus135, 64-78). Under the influence of varying diurnal tides, strike-slip offset may have occurred through a process called "walking," which depends upon an inelastic lithospheric response to displacement. Alternatively, fault displacement may have been driven by currents in the theorized Europan ocean, which may have created simple shear structures such as braids. The discovery of Astypalaea Linea extends the geographical range of lateral motion on Europa. Such motion requires the presence of a decoupling zone of ductile ice or liquid water, a sufficiently rigid lithosphere, and a mechanism to consume surface area.

Original languageEnglish (US)
Number of pages1
JournalIcarus
Volume141
Issue number1
DOIs
StatePublished - Sep 1999

Keywords

  • Europa
  • Satellite
  • Satellites of Jupiter
  • Surfaces
  • Tectonics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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