Afterslip no longer an afterthought

摘要

If you have ever felt the eerie ground-shaking that accompanies an earthquake, then you are one of millions of people who have briefly experienced the dance of the tectonic plates that slowly drift across the Earth's surface. But earthquakes account for only a fraction of the plate displacements that are predicted by models of present-day plate velocities, thereby indicating the existence of a 'seismic slip deficit. Using a relatively new technique for measuring active crustal deformation, Heki and colleagues (page 595 of this issue) demonstrate that seismically invisible slip following earthquakes accounts for some of this deficit. Their work, when combined with other observations of strain release along plate boundaries, bolsters the case that steady motion between plates is accommodated by a continuum of processes that include slow-rupture earthquakes, silent earthquakes, aseismic creep and afterslip (Fig.1).