2010 Chile Earthquake: The Maule Quake and Its Coastal Tsunami

The 2010 Chile earthquake, also called the Maule earthquake, was a magnitude 8.8 earthquake that struck off the coast of central Chile at 3:34 a.m. on 27 February 2010. The shaking and the tsunami that followed killed about 525 people and caused damage estimated at around 30 billion US dollars. It was one of the largest earthquakes ever recorded, yet Chile’s strict building standards meant that the toll was far lower than in many smaller disasters.

Background

Chile lies along one of the world’s most active plate boundaries, where the oceanic Nazca plate slides beneath the South American plate at about 7 centimetres a year. This subduction zone produced the largest earthquake ever recorded, the magnitude 9.5 Valdivia earthquake of 1960, further south. The section of the fault off Maule and Biobío had last ruptured in a great earthquake in 1835, described by Charles Darwin, who visited Concepción during the voyage of the Beagle.

Because of this history, Chile had developed strict seismic building codes, revised after a damaging earthquake in 1985. The country was also politically in transition: President Michelle Bachelet was in the last days of her term, and Sebastián Piñera was due to take office on 11 March 2010.

The earthquake and tsunami

The rupture began roughly 20 to 35 kilometres below the seabed off the coast of Maule Region and spread along roughly 500 kilometres of the fault. Strong shaking lasted around two to three minutes and was felt across much of Chile and in Argentina. The cities of Concepción and Talca and many small towns suffered heavy damage, and buildings were also damaged in Santiago, about 330 kilometres from the epicentre.

Within minutes, tsunami waves reached the coast. They devastated the port of Talcahuano, the seaside towns of Constitución, Dichato and Pelluhue, and the island of Robinson Crusoe in the Juan Fernández archipelago, about 670 kilometres offshore. Water ran up to heights of up to about 29 metres in a few places near Constitución, though along most of the coast the waves were a few metres high.

The tsunami crossed the Pacific, prompting warnings and evacuations in Hawaii, Japan, New Zealand and elsewhere, but it caused little damage outside Chile.

The earthquake was so large that it measurably changed the shape of the land. GPS measurements showed that Concepción had moved about 3 metres to the west, and parts of the coast were lifted or lowered by up to 2 metres or more. Thousands of aftershocks followed in the weeks after the main shock, several of them above magnitude 6.

The warning failure

In the dark and confusion after the earthquake, Chile’s warning system broke down. The navy’s hydrographic and oceanographic service (SHOA) and the national emergency office (ONEMI) failed to issue a clear tsunami alert, and officials told the public that a tsunami was not expected. Some campers and residents who stayed on the coast were killed by the waves.

Many people survived because they followed long-standing local knowledge: after a strong earthquake near the sea, move to high ground immediately. The failure led to official investigations and a major reform of Chile’s tsunami warning and emergency services.

Damage and response

About 370,000 homes were damaged or destroyed, many of them older adobe houses in rural areas. Roads, bridges, ports, hospitals and the airport at Santiago were damaged. In Concepción, a newly built 15-storey apartment block, the Alto Río building, collapsed, killing several people and prompting scrutiny of its design.

Looting broke out in Concepción in the days after the disaster, and the government deployed troops and imposed a curfew. President Bachelet was criticised for a slow initial response, and Piñera’s incoming government launched a large reconstruction programme. Total damage was estimated at about 30 billion US dollars, roughly 15 to 18 percent of Chile’s annual economic output.

Timeline

• 1835, 20 February: A great earthquake strikes the same region, witnessed by Charles Darwin.
• 2010, 27 February, 3:34 a.m.: A magnitude 8.8 earthquake strikes off Maule Region.
• 2010, 27 February, early morning: Tsunami waves strike Talcahuano, Constitución, Dichato and Robinson Crusoe Island.
• 2010, 28 February: Troops are deployed and a curfew is imposed in Concepción after looting.
• 2010, 11 March: Sebastián Piñera takes office; strong aftershocks shake central Chile on the same day.

Legacy

The Maule earthquake became a case study in earthquake engineering. Despite the enormous shaking, relatively few modern buildings collapsed, a result widely credited to Chile’s building codes and their enforcement. The contrast with the Haiti earthquake six weeks earlier, which was far smaller but killed vastly more people, was widely noted.

The failure of the tsunami warning, however, showed that preparedness depends on people and procedures as well as buildings. Chile reformed its warning system, and evacuations during later earthquakes, such as the magnitude 8.3 Illapel earthquake of 2015, were faster and more effective.

Why it matters

The 2010 Chile earthquake was one of the most powerful ever recorded. It showed both the life-saving value of strong building standards and the deadly consequences of a failed tsunami warning, lessons studied by earthquake-prone countries worldwide.