Shear zone evolution and the path of earthquake rupture
نویسندگان
چکیده
Abstract. Crustal shear zones generate earthquakes, which are at present unpredictable, but advances in mechanistic understanding of the earthquake cycle offer hope for future forecasting. Studies fault zone architecture have potential to reveal controls on rupture, locking, and reloading that control temporal spatial patterns earthquakes. The Pofadder Shear Zone exposed Orange River South Africa is an ancient, exhumed, paleoseismogenic continental transform preserves source near base seismogenic zone. To investigate rupture geometries crust, we produced a high-resolution geologic map core mylonite consists ∼ 1–200 cm, pinch-and-swell layers mylonites variable mineralogic composition, reflecting diversity regional rock types were dragged into Our displays centimetric unique black ultramylonite along some interfaces, locally adding thick composite suggesting reactivation or bifurcation. We set criteria identifying recrystallised pseudotachylytes (preserved frictional melts) show pseudotachylyte, with its distribution representing ancient surfaces. Pseudotachylytes most abundant interfaces between strongest wall rocks. find geometry lithologic hosted earthquakes differs from lacking pseudotachylyte wavelengths ≳ 10 m. argue structure mylonitic layering, enhanced by viscosity contrasts different mineralogy, expected spatially heterogeneous stress during viscous creep zone, dictated path ruptures. condition rheologically layered materials causing stresses should be reasonably any major creep, represents pre-seismic background conditions through nucleate propagate. This has implications recurrence explains why surfaces favored over others.
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ژورنال
عنوان ژورنال: Solid Earth
سال: 2022
ISSN: ['1869-9529', '1869-9510']
DOI: https://doi.org/10.5194/se-13-1607-2022