On early morning Sunday, July 30, 1995, at 01:11 local time, an earthquake took place in northern Chile (23° 21.72'S, 70° 21.6'W, 05:11:23.7 UTC, NEIC), nearby the city of Antofagasta. Initial estimates of magnitude were: mb=6.6, Ms=7.8 (QED), Mw=7.3 (Kawakatsu), Mw=7.5, h=57 km (Sipkin), Mw=8.1 (Harvard).

Damage was concentrated in the city of Antofagasta, particularly in the sea port, only 30% of its capability can continue operations. Three persons lost threir lives and more that a dozen were injured. From the initial 50+ houses scheduled to be demolished, now the count stands in the 300's.

More than thirty 4+ magnitude aftershocks have been recorded during the first forty hours, being the largest a 6.1 event.

From the aftershocks distribution a rupture area of about 180 km by 70 km emerges, this elongated in a north-south direction and it is located partly inland and partly offshore. The low dip angle (19 degrees) of this almost pure thrust event, precluded the generation of a tsunami. Reports of high marks of water were between 1 1nd 1.5 m above the tide.

It is a gap filling event, it extends from Antofagasta at the northern extreme to the latitude of village of Paposo, about 180 km to the south. Previous large magnitude earthquakes in this region are the March 5, 1987 (Ms=7.3) and the Dec 28, 1966 (Ms=7.8) Tal-Tal earthquake.

No local tsunami was reported, this is mainly due to the fault plane location. It lies right under the coast, some aftershocks offshore and some aftershocks inland. Rupture length is about 180 km (width around 70-80). We estimate that there should have been coastal uplift of about 1 m. Some fishermen say that there was only a wave about 1.5 m above normal tide.

More information and details on intensities can be found on our Web page http://www.dgf.uchile.cl

Sergio Barrientos

Depto. de Geofisica
Universidad de Chile