Co-seismic slip, post-seismic slip, and aftershocks associated with two large earthquakes in 1996 in Hyuga-nada, Japan

We analyzed continuous GPS data to investigate the spatial distribution of post-seismic slip associated with two large earthquakes of October 19 and D ecember 2, 1996, in Hyuga-nada, Japan. We found that the moment release due to post-seismic events was comparable to the co-seismic moment release dur ing the two earthquakes. The source parameters of the first post-seismic ev ent are as follows: the moment release = 1.7 x 10(19) Nm; the maximum slip = 0.06 m at about 50 km northwest from the epicenter of the first earthquak e; the characteristic decay time (= final slip/initial slope) = 15 days. Fo r the second post-seismic event, the moment release = 2.0 x 10(19) Nm; the maximum slip = 0.13 m at about 15 km northwest from the epicenter of the se cond earthquake; the characteristic time = 100 days. In both events, the sl ip vectors of the downgoing Philippine Sea (PHS) Plate on the SW-striking i nterplate boundary are directed west, in accordance with the co-seismic sli p. It is also shown that the sites for co-seismic slip, post-seismic slip, and aftershocks do not overlap but complementarily share the plate boundary . This suggests that individual sites are characterized by their own consti tutive laws, which may control modes of moment release as well as the entir e sequence.