Epicenter distribution and magnitude of earthquakes in fold-thrust belts : insights from sandbox models

• Scaled analogue models are used to illustratethe eect of basal friction and erosion on fault activity andhence on epicentre distribution and magnitude of earth-quakes in the sedimentary cover of active fold-thrust belts.Model results suggest that in fold-thrust belts shortenedabove low-friction ductile decollements (rock salt or over-pressured mudstone), low- to moderate-magnitude earth-quakes (Mw=5:3−5:6), distributed over a wide area, occuralong several long-lived thrust faults. Conversely, in areasshortened above high-friction decollements large-magnitudeearthquakes (Mw=6:6−6:8), distributed over a narrowzone are likely to occur along few short- lived thrust ramps.Calculated magnitude of earthquakes from models and theirdistribution are in agreement with recorded earthquake pat-tern from the Zagros mountain belt, which is partially short-ened above a ductile decollement of Hormuz salt formation.Model results also showed that erosion reactivates older in-active thrusts and promotes formation of out-of-sequencethrusts.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

WEDGES; HIMALAYAS; BEHAVIOR; GEOMETRY; SYSTEMS; IRAN; SALT

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