Fig. 10: LFE stress drop, rupture dimensions, and average slip as a function of rupture velocity (modified from⁹).

The estimated constant stress drop is shown (coloured circles) for a rupture velocity that varies from 0.02 β (where β = S-wavespeed) to 0.9 β. Minimum and maximum potential rupture dimensions of the low frequency earthquakes (LFEs) are shown (circle labels), as are their average slips (circle colours). Circle sizes are scaled to the average rupture dimensions. Tidal stresses (grey box)⁸ and teleseismic triggering stress levels (lined box)⁶⁵ are also shown. Reference values for the rupture velocity are given at the top of the Figure, for the assumption β = 3.7 km s⁻¹. The most likely conditions for LFE slip are highlighted by the colour-shaded regions. These involve stress drops greater than observed triggering stress perturbations due to tidal stresses or passing teleseismic waves, and rupture velocities greater than ~200 m s⁻¹, which implies LFE rupture surface diameters of order ~30–400 m, and event slips of order ~0.0004–0.002 m.