Bulletin of the Seismological Society of America; February 2006; v. 96; no. 1;
p. 90-106; DOI: 10.1785/0120050067
© Seismological Society of America
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Figure 9. (a) Forecasted number of events with m 
2 per cell for 23 October
2004 (logarithmic scale). Black circles represent observed earthquakes with
m 2 that occurred during this day. Two of these events are
aftershocks of the m 6.5, 22 December 2003 San Simeon earthquake
(located at latitude 35.7° and longitude –121.1°), three
are associated with the m 6 28 September 2004 Parkfield
mainshock (latitude 35.81° and longitude –120.37°), and one is an
aftershock of a m 3.7 9 September 2004 earthquake (latitude
35.09° and longitude –117.52°). The predicted number of events for
this day was 8.39 and the observed number was 6. Most of these earthquakes are
better predicted by the ETES model than by the time-independent model
(i.e., Np > µ in the cells within which these
earthquakes occurred). Only one event, which occurred at 11 km away from
the San Simeon earthquake (latitude 35.81° and longitude
–121.02°), was better predicted by the time-independent model, because
it occurred just outside of the main aftershock zone. (b) Ratio of the
forecasted number of events estimated using the ETES and the
time-independent models (logarithmic scale). High values of
Np/µ (up to 800) are associated with recent
large earthquakes, such as Parkfield, San Simeon, Landers, Hector Mine, and
Northridge.
