Liquefaction Observed During The 2010 Chile Earthquake

On February 27, 2010, at 3: 34 a.m. local time, a large earthquake of Magnitude 8.8 hit the Central-South region of Chile. A significant number of aftershocks followed the initial quake, being the most important of Magnitude 6.2, which occurred 20 min after the main shock. The 2010 Chile Earthquake has been identified as a thrust-faulting type that occurred on the interface between the Nazca and South American plates, at an average depth of 35 km. Seismologists have reported that the rupture zone covered a rectangular area of approximately 550 km by 170 km. High horizontal peak ground accelerations were recorded on soil deposits, being the maximum one 0.94 g at Angol City, located towards South of the rupture zone. To the north of the rupture zone, the horizontal peak ground accelerations (PGA) was recorded in Melipilla City, reaching a value of 0.78 g. Several of the available records show a ground motion that exceeds 2 min of duration, which may explain the significant amount of liquefied sites. Field observations have shown that the earthquake triggered liquefaction in more than 170 different sites, covering a north-south distance of about 950 km, which approximately corresponds to twice of the length of the rupture zone. Liquefaction phenomenon induced damages to the road infrastructure, railroads system, buildings and houses. Liquefaction-induced ground failure displaced and distorted pile foundations of piers impacting seriously the operation of several ports. Especially interesting is the case of Juan Pablo II Bridge, where significant differential settlements were observed, but almost non transversal lateral displacements took place.