Megathrust earthquake causes ‘widespread damage’ in Ecuador

A major earthquake has struck the central coast of Ecuador.

The United States Geological Survey (USGS) has estimated moment magnitude at 7.8 and focal depth at a relatively shallow 19 km (11.8 miles). Widespread damage is reported.

A breakdown of public order has been reported in the city of Portoviejo, prompting mobilisation of 10,000 troops.

According to catastrophe modeling firm AIR Worldwide, the epicentre of the quake was located on a relatively sparsely populated part of the Ecuadoran coast near the northern town of Muisne. Damage, however, has been reported at considerable distance from the epicentre. Roads have been made impassible by large cracks, and power and communications are out in the affected area.  It will take some time before the extent and degree of damage from the current event are fully known, said AIR.

According to firm, seismic hazard in Ecuador is driven primarily by the Nazca subduction zone, which is located just offshore of western South America.

The megathrust earthquake occurred as the result of shallow thrust faulting on or near the plate boundary between the Nazca and Pacific plates, according to the USGS. Here the Nazca plate is subducting eastward beneath the South America plate at a velocity of 61 mm/yr.

Several earthquakes of magnitude 7.0 or greater have affected Ecuador since 1900, including a M7.1 earthquake that caused considerable damage in Manabi province in 1998. In Bahia de Caraquez, a coastal city, that earthquake damaged many engineered mid-rise and high-rise buildings. Fully 71 percent of the city’s reinforced concrete buildings suffered some degree of damage, and 17 percent of these buildings collapsed or were damaged beyond repair. In the town of Canoa, 60 percent of structures were damaged.

The subduction off the west coast of South America has led to uplift of the Andes mountain range and has produced some of the largest earthquakes in the world, including the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile.