What are the different kinds of faults?
Faults are identified by how the two blocks on either side of the fault move. Some types of faulting are driven by extension, others by compression. Animations show the various fault types. • Q: What are foreshocks and aftershocks? A: “Foreshock” and “aftershock” are relative terms. Foreshocks are earthquakes which precede larger earthquakes in the same location. Aftershocks are smaller earthquakes which occur in the same general area during the days to years following a larger event or “mainshock.” As a general rule, aftershocks represent minor readjustments along the portion of a fault that slipped at the time of the main shock. The magnitude 5.0 Robinson Point earthquake of January 28, 1995 that occurred in the Seattle – Tacoma region was preceded by two “unfelt” foreshocks of magnitudes 0.7 and 1.8. Similarly, roughly twenty five “unfelt” aftershocks less than magnitude 2.0 occurred in the region after the M 5.0 earthquake. The frequency of these aftershocks decreases with time. Hi
