The western coast of South America is a section of the Circum-Pacific Belt (seismic belt), which is prone to high-magnitude earthquakes. The Andes range and Peru-Chile trench have experienced some of the most destructive temblors in history; the earthquake that hit Peru in 1970 being one of them. Also known as the Great Peruvian Earthquake or the 1970 Ancash earthquake, it was a high-magnitude undersea quake that rocked the Peruvian regions of Ancash and La Libertad on the afternoon of May 31, 1970.
Intensity of the Earthquake
The earthquake, which lasted for about 45 seconds, occurred at 15:23:31 local time. The epicenter of this quake was located 22 mi (35 km) off Peru coast in the Pacific Ocean. The quake having a magnitude of 7.9 to 8.0 on the Richter scale, showed an intensity of 8 on the Mercalli intensity scale used to measure the intensity of earthquakes. Tremors were also felt in Brazil and Ecuador.
The northern wall of the Nevado Huascarán, a mountain in the Yungay province, was destabilized due to this earthquake. This destabilization triggered an avalanche that buried the towns of Yungay and Ranrahirca under rock debris, ice, and snow. A 3000-ft wide and 1-mi long mass of glacial ice and rock detached itself from the mountain. It skidded for approximately 11 mi and came down on Yungay town. This mass of ice was moving at a speed of more than 100 miles an hour. On its way, it collected glacial deposits, rocks, and mud, and by the time it came down on the village at the foot of the mountain, it was carrying 80 million cubic meters of matter that buried the entire town beneath it.
Effects of the Earthquake
An area of about 32,000 sq mi (83,000 sq km), extending over Ancash and La Libertad regions, was affected due to this seismic movement. Over 3 million people had to bear the brunt of this natural calamity. Around 74,194 individuals lost their lives, as many as 25,600 went missing, and 143,331 were injured. At least 20,000 people died in the landslide in Yungay town alone. Additionally, more than a million people were left homeless.
The quake had a huge impact on the infrastructure of the region. Almost the entire communication system was destroyed. The economic loss was estimated to be more than half a billion USD. All the basic facilities were either seriously damaged or totally destroyed. More than 80 percent buildings in the cities of Chimbote, Carhuaz, and Recuay were razed to the ground. The coastal areas were the most affected. Cities like Chimbote, Casma, Huarmey, and Supe suffered large-scale damage, while cities like Huaraz, Caraz, and Aija were partly damaged.
The Cañón del Pato hydroelectricity generator was damaged due to excessive flooding of River Santa. Damage induced to the Pan American highway resulted in delay of humanitarian aid to the affected areas.
The entire town of Yungay, which got buried beneath snow and rock debris, has been preserved as a national cemetery. As a remembrance of this quake, May 31 is observed as the Natural Disaster Education and Reflection Day in Peru. Every year, on this day, an earthquake drill is practiced in schools of Peru to commemorate this calamity.
Even though other parts of the world have experienced earthquakes of higher magnitudes, the havoc caused by the landslide and floods triggered by this earthquake, make it one of the most devastating natural calamities ever to befall mankind.