Constraints on slow earthquake dynamics from a swarm in central italy, Science 286 (5447

Several clustered slow earthquakes have been recorded by a geodetic inter-ferometer in central Italy. The strain rise times of the events range from tens to thousands of seconds, and the seismic moment scales with the square root of the rise time. This scaling law contrasts with the conservative assumption of constant rupture velocity in fault modeling but is consistent with the oc-currence of a slow rupture propagation analogous to heat diffusion in a slab. Slow earthquakes have been observed in Japan and California as nearly exponential strain changes with durations ranging from about 1 hour to 3 days and strain steps larger than 3 3 1028 (1–4). Indirect evidence for slow earthquakes comes from seismograms with anomalous long-period spectral behav-ior (5–9). In these cases, the durations of the slow earthquakes range from a few second