POSTSEISMIC COASTAL UPLIFT IN SOUTHERN CHILE

Tide gage records at Puerto Montt, referenced to a mareograph in Talcahuano, indicate a large (at least 75 cm) postseismic uplift of the region following the 1960 M(W) = 9.5 event. Field observations carried out in 1989 at the same locations of previous measurements in 1968 are consistent with tide gage records. The postseismic elevation changes are modeled as the result of propagating creep on the downdip extension of the coseismic fault. For a 30-degrees E fault dip, minimum square error indicates a fault creep velocity of 4-6 km/yr and slip amplitude of 3-5 m.