|Magnitude 7.1 Ms|
|Areas affected Chile|
|Date October 15, 1997 (1997-10-15)|
The 1997 Punitaqui earthquake occurred at 01:03 UTC on October 15. It had an estimated magnitude of 7.1. This earthquake was one of the most destructive in the epicentral area compared to other events of subduction of the same size. The extensive damage to structures was the result of an amplification effect on the ground and the poor quality of building materials, this reflects the potential for damage incurred in an intraplate earthquake with vertical fault and how it can be much greater than what which can cause one of interplate of similar magnitude, and caused severe damage in Chilean cities of La Serena, Ovalle, Illapel and Punitaqui.
The earthquake took place along the boundary between the Nazca and South American tectonic plates, at a location where they converge at a rate of seventy millimeters a year. This quake was an oceanic interplate type, occurred in the going slab and not between two plates, the effect of friction, referring to the Nazca and South American Plate. In particular, this event took place under the area of coupling seismic, besides his epicenter is located in an area specific to Chile, ranging between 27° and 33° S, where the going slab is placed almost horizontally at 100 km (62 mi). deep and goes nearly 250 km (155 mi). into the mainland under the continental plate, it generates a large coupling of the two plates in contact and absence of volcanism, among other things.
The October earthquake occurred in the rupture zone caused by the 1943 Ovalle earthquake which had a magnitude of 8.7 MW, as well as related with other quakes occurred in the same area like the Valparaiso earthquake of August 1730, of 9.2 MW and the 1880 Illapel earthquake which registered a magnitude of 8.8 MW. This entire segment is delimited by the rupture zoans of 1965 and 1971 in Aconcagua and 1906 in Valparaíso to the south, while to the north by the 1922 ruptured in Atacama Region.
Punitaqui was practically demolished by the quake, which reached an VIII-magnitude seismic Mercalli. Damage ranged from as far north as the Antofagasta Region to the southern Araucanía Region.
In Santiago, the quake felt undulating because of the distance from the epicenter. Both Santiago and Valparaíso regions lost telephone service and radio transmission. In La Serena, hysteria broke out, and people went into the streets as a precaution. The quake left 8 people dead, 160 injured and 10,913 homeless, concentrating most of those in the provinces of Elqui and Limarí.