The 1960 Valdivia earthquake struck Chile on the afternoon of 22nd May 1960, causing widespread damage with Valdivia being the most affected city. Also known as the Great Chilean earthquake, it was a 9.5 MW earthquake making it the most powerful ever recorded till date. The tremor triggered a giant tsunami which caused destruction and deaths as far away as Japan, around a day later. Know about the cause, effects, damage and death toll of the 1960 earthquake in Chile through these 10 interesting facts.
#1 THE GREAT CHILEAN EARTHQUAKE WAS A MEGATHRUST EARTHQUAKE
Subduction is a process that occurs at convergent boundaries of tectonic plates due to the movement of one plate under another. Regions where it occurs are known as subduction zones. Subduction zones produce the strongest earthquakes on earth as their structure allows more stress to accumulate before the energy is released. Earthquakes occurring at subduction zones are known as megathrust earthquakes and nine of the ten most powerful earthquakes in the twentieth century were megathrust, including the 1960 Chile earthquake.
#2 IT WAS CAUSED DUE TO THE SUBDUCTION OF NAZCA PLATE UNDER THE SOUTH AMERICAN PLATE
The South American Plate is a tectonic plate which includes the continent of South America and a sizable region of the Atlantic Ocean seabed. The Nazca Plate is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The Chile earthquake of 1960 was caused by the release of mechanical stress due to the subduction of the Nazca Plate under the South American Plate along the Chile-Peru Trench, which has been the cause of many other earthquakes too.
#3 IT WAS PRECEDED BY THE 1960 CONCEPCIÓN EARTHQUAKES
Before the Great Chilean earthquake, three earthquakes struck Chile which were a fore-shock to the main event and are known as the 1960 Concepción earthquakes. The first Concepción earthquake struck at 06:02 on 21st May 1960. It had a magnitude of 8.1, lasted for 35 seconds and destroyed a third of the buildings in the city of Concepción in Chile. The second earthquake happened the following day at 06:32 and had a magnitude of 6.8, while the third was sized 7.9 and happened at 14:55 on 22nd May, just 15 minutes before the Valdivia earthquake.
#4 THEEPICENTEROF THE 1960 VALDIVIA EARTHQUAKE WAS NEAR LUMACO
The epicenter of the 1960 Valdivia earthquake lay around 100 miles of the coast of Chile in the Pacific Ocean. It was near the town of Lumaco, which is around 570 km south of the Chilean capital Santiago. The focus of the earthquake was relatively shallow at 33 km, as other earthquakes in the region are known to reach depths of 70 km. Focus is the point where an earthquake originates while epicenter is the point on Earth’s surface directly above the focus.
#5 THE MOST AFFECTED CITY IN THE EARTHQUAKE WAS VALDIVIA
The Great Chilean earthquake occurred at 15:11 on 22nd May 1960. It lasted for 11 to 13 minutes and affected all of Chile between Talca and Chiloé Island, an area more than 400,000 squarekilometers. The towns of Valdivia and Puerto Montt suffered the maximum damage. The electricity and water systems of Valdivia were totally destroyed; and around 20,000 people were left homeless due to the destruction of approximately 40 percent of the houses in the town. The port of Puerto Montt collapsed. The train station and numerous buildings in the town were destroyed.
#6 IT CAUSED TSUNAMIS WHICH WERE PRIMARILY RESPONSIBLE FOR THE DAMAGE
Though the tremor caused significant damage, it was the resulting tsunamis or high waves which were responsible for major destruction. The tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia and the Aleutian Islands. Waves as high as 10.7meters(35 ft)were recorded 10,000kilometersfrom the epicenter, and as far away as Japan and the Philippines. 2 million people were left homeless due to the destruction caused by the 1960 Valdivia earthquake and the resultant landslides and tsunamis.
#7 VALDIVIA EARTHQUAKE TSUNAMI HIT JAPAN AROUND A DAY LATER
The Chilean coast was severely battered by the localized tsunamis which reached a height up to 25 m (82 ft) and caused numerous fatalities. The main tsunami raced across the Pacific Ocean and when it reached Hawaii, the waves still had a max height of 10.6 m (35 ft). They killed 61 people and caused $24 million in damage at Hilo Bay on the main island of Hawaii. Waves, as high as 5.5 m (18 ft), struck the Japanese island of Honshu around 22 hours after the earthquake, killing 138 people and destroying 1600 homes. Another 32 people were dead or missing in the Philippines after the tsunami hit those islands.
#8 WAVES SET OFF BY IT BOUNCED BACK AND FORTH ACROSS THE PACIFIC FOR A WEEK
The waves set off by the Great Chilean earthquake bounced back and forth across the Pacific Ocean for a week. Aftershocks were recorded for around a month after the main tremor. On 24 May, 38 hours after the 1960 Valdivia earthquake, the Cordón-Caulle volcano in Los Lagos region of Chile erupted after nearly 40 years of inactivity. Some seismologists believe the eruption was linked to the Valdivia earthquake.
#9 IT CAUSED 1,000 TO 6,000 DEATHS
The death toll and the monetary losses caused by the earthquake cannot be stated with certainty. The monetary cost of the disaster has been estimated in the range of US$400 million to US$800 million (2.9 to 5.8 billion in 2011, after adjusting for inflation). Studies have estimated the total number of fatalities at 1,655, 2231, 3000, 5700 and even 6,000. The death toll for the 1960 Valdivia earthquake was less considering its magnitude. This was because it occurred in the afternoon, many of the structures in affected areas were earthquake-resistant and thefore-shocksmade the population wary.
#10 IT IS THE MOST POWERFUL EARTHQUAKE EVER RECORDED
The moment magnitude scale (MW) is used to measure the size of earthquakes in terms of energy released. It is the most commonly used scale to measure medium to large earthquake magnitudes. An increase of two points on the scale corresponds to 1000 times increase in energy. Thus an MW 7.0 quake contains 1000 times the energy of a 5.0 MW quake and about 32 times of a 6.0 MW quake. Great Chilean earthquake measured 9.5 on the MW making it the largest earthquake of the twentieth Century and the most powerful ever recorded. Among recorded earthquakes, it is followed by 9.2MW 1964 Alaska earthquake and (9.1–9.3) MW Indian Ocean earthquake of 2004.
THE 2010 CHILE EARTHQUAKE
Chile was struck again by a powerful earthquake of 8.8MW in 2010. It was the fifth largest earthquake ever to be recorded by a seismograph and ranks thirteen in the overall list including estimates. The 2010 quake was also megathrust and caused by the subducting Nazca plate under the South American plate. It damaged 370,000 homes in Chile and at least 525 people were killed. The cost of the earthquake was estimated between 4 and 7 billion dollars.
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Now, let's dive into the information related to the concepts mentioned in the article about the 1960 Valdivia earthquake in Chile:
1. The Great Chilean Earthquake was a Megathrust Earthquake
The 1960 Valdivia earthquake, also known as the Great Chilean earthquake, was a megathrust earthquake. Megathrust earthquakes occur at subduction zones, where one tectonic plate is forced beneath another. These types of earthquakes produce the strongest seismic activity on Earth. In fact, nine out of the ten most powerful earthquakes in the twentieth century were megathrust earthquakes, including the 1960 Chile earthquake .
2. Cause of the Earthquake: Subduction of the Nazca Plate under the South American Plate
The 1960 Chile earthquake was caused by the subduction of the Nazca Plate under the South American Plate along the Chile-Peru Trench. The Nazca Plate is an oceanic tectonic plate in the eastern Pacific Ocean basin, while the South American Plate includes the continent of South America and a region of the Atlantic Ocean seabed. The release of mechanical stress during the subduction process led to the earthquake.
3. Preceding Earthquakes: The 1960 Concepción Earthquakes
Before the Great Chilean earthquake, three earthquakes struck Chile, known as the 1960 Concepción earthquakes. These were fore-shocks to the main event. The first Concepción earthquake occurred on May 21, 1960, with a magnitude of 8.1. The second earthquake happened on May 22, 1960, just 15 minutes before the Valdivia earthquake, with a magnitude of 7.9. These preceding earthquakes contributed to the overall seismic activity in the region .
4. Epicenter of the 1960 Valdivia Earthquake
The epicenter of the 1960 Valdivia earthquake was near the town of Lumaco, approximately 100 miles off the coast of Chile in the Pacific Ocean. The focus of the earthquake was relatively shallow at 33 km, while other earthquakes in the region can reach depths of 70 km. The most affected city by the earthquake was Valdivia, where significant damage occurred.
5. Most Affected City: Valdivia
The Great Chilean earthquake affected all of Chile between Talca and Chiloé Island, an area of more than 400,000 square kilometers. However, the towns of Valdivia and Puerto Montt suffered the most damage. In Valdivia, approximately 40 percent of the houses were destroyed, leaving around 20,000 people homeless. The electricity and water systems of Valdivia were also completely destroyed. In Puerto Montt, the port collapsed, and numerous buildings, including the train station, were destroyed.
6. Tsunamis Caused by the Earthquake
While the earthquake caused significant damage, it was the resulting tsunamis that were primarily responsible for major destruction. The tsunamis affected various regions, including southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and the Aleutian Islands. Waves as high as 10.7 meters (35 ft) were recorded 10,000 kilometers from the epicenter, reaching as far as Japan and the Philippines. The destruction caused by the earthquake, landslides, and tsunamis left approximately 2 million people homeless .
7. Tsunami Impact on Japan
The Valdivia earthquake tsunami reached Japan around 22 hours after the earthquake. Waves as high as 5.5 meters (18 ft) struck the Japanese island of Honshu, resulting in the deaths of 138 people and the destruction of 1,600 homes. The localized tsunamis along the Chilean coast caused severe damage, and when the main tsunami reached Hawaii, it still had a maximum height of 10.6 meters (35 ft), resulting in 61 deaths and significant damage at Hilo Bay.
8. Waves Bouncing Back and Forth Across the Pacific
The waves generated by the Great Chilean earthquake bounced back and forth across the Pacific Ocean for about a week. Aftershocks were recorded for approximately a month after the main tremor. Additionally, the Cordón-Caulle volcano in the Los Lagos region of Chile erupted 38 hours after the earthquake, which some seismologists believe was linked to the Valdivia earthquake .
9. Death Toll Estimates
The exact death toll and monetary losses caused by the earthquake are uncertain. Various studies have estimated the total number of fatalities to be between 1,000 and 6,000. The monetary cost of the disaster has been estimated to range from US$400 million to US$800 million (adjusted for inflation). The death toll was relatively lower considering the magnitude of the earthquake due to factors such as earthquake-resistant structures in affected areas and the population being wary after the preceding fore-shocks .
10. The Most Powerful Earthquake Ever Recorded
The 1960 Valdivia earthquake is the most powerful earthquake ever recorded. It had a moment magnitude (MW) of 9.5, making it the largest earthquake of the twentieth century. The moment magnitude scale measures the size of earthquakes in terms of energy released. An increase of two points on the scale corresponds to a 1000-fold increase in energy. The 1960 Valdivia earthquake is followed by the 1964 Alaska earthquake with a magnitude of 9.2 MW and the 2004 Indian Ocean earthquake with a magnitude of 9.1-9.3 MW .
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