The strongest earthquake ever recorded on Earth

Lorenzo Pasqualini Meteored Italia 18 Jun 8 min
earthquake seismograph
Never before have seismographs recorded an earthquake as strong as that of 1960 in Chile.

On May 22, 1960, 62 years ago, The strongest earthquake ever recorded with instruments in the history of mankind occurred. With a moment magnitude Mw 9.5, the enormous mega-earthquake also produced a very violent tsunami, with waves up to 25 meters high, that spread for thousands of kilometers in the Pacific Ocean. The tsunami caused thousands of victims in Chile, y dozens of deaths also in areas of the globe located many thousands of kilometers from the epicenter.The epicenter of the earthquake was located off the coast of southern Chile and the event is remembered as the “Valdivia earthquake”, because he severely damaged this city. It is also remembered as the “great earthquake in Chile”.

The tsunami devastated the coast of Isla Mochain Chile, then the tsunami spread for thousands of kilometers in the Pacific Ocean, reaching Hawaii after about 15 hours, with waves exceeding 10 meters in height. The tsunami also reached distant New Zealandwhere the waves reached 10 meters, and even reached Japan, on the opposite shore of the Pacific, more than 15,000 kilometers away!

The earthquake of May 22, 1960, with an impulse magnitude of Mw 9.5, is known as the Valdivia Earthquake. or Great Chile Earthquake.

An earthquake of enormous proportions

The exact number of victims of the Great Chile Earthquake will never be known, but the most accurate estimates indicate at least three thousand dead, many of them caused by the tsunami. There were more than two million people displaced and enormous damage. Compared to the strength of the earthquake, the damage and repercussions were relatively small, considering that other smaller earthquakes have caused hundreds of thousands of victims.

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In fact, in the damage caused by an earthquake weigh many factorsin between them the greater or lesser proximity of the inhabited areas to the epicenter, the way in which the seismic waves are amplified by the terrain and the elements of the local geography. In the case of the Valdivia earthquake, the areas closest to the epicenter were sparsely populated.

The earthquake also woke up the Puyehue volcano, located in the Andes mountain range.

As we said, the 1960 earthquake was the strongest recorded earthquake instrumentally in the history of mankind. It means that since we recorded the power of earthquakes with instruments, this was the strongest earthquake. Earthquakes are recorded with instruments called seismographs.

Magnitude 9.5: how strong is an earthquake like this?

To express the power of an earthquake, the magnitude is used, which indicates the energy released. The smallest earthquakes perceived by man have very low magnitudes, around 2.0 (and you have to be very close to the epicenter to feel them), while magnitudes greater than 5.5 can cause significant damage.

An earthquake causes damage if the epicenter is near inhabited areas or if seismic wave amplification phenomena occur, to name a few. Obviously, it also weighs a lot vulnerability of housing and infrastructure. Another important factor is the depth at which the earthquake occurred (hypocenter), because very deep earthquakes will have less impact.

The strongest earthquakes ever seen on Earth: the strongest is that of 1960 in Chile.

Precisely because great magnitude is not always synonymous with devastation, another way of measuring an earthquake is using the intensity scale, that takes into account the effects on the environment and on things built by man. The intensity of an earthquake is expressed with the Mercalli scale, then modified in the MCS escala (Mercalli-Cancani-Sieberg). This goes up to grade XII: in that case, we speak of total destruction. A very high-magnitude earthquake in the open desert, far from any cities, will probably have a minimal intensity, because it will cause no damage.

And we reached the magnitude of an earthquake with a magnitude of 9.5 like that of Chile, the magnitude is expressed on a logarithmic scale, so each degree increase corresponds to an increase in energy of about 30 times. A magnitude 7 earthquake will be 30 times stronger than a magnitude 6 earthquake, and a magnitude 8 earthquake will be 30×30 times stronger, that is, 900 times stronger.

The tsunami spreads across the planet

The magnitude of the Valdivia earthquake and tsunami gave a strong impetus to the creation of a tsunami early warning system. Below you can see the reconstruction of how the tsunami waves spread in the Pacific Ocean.

The earthquake occurred in the subduction zone where the Nazca tectonic plate meets the South American plate.sinking below it in the ocean trench at a rate of almost 10 centimeters each year (very high values).

This zone of collision between the plates is located along the entire coast of Chile, and is part of the so-called “Pacific Ring of Fire”. The Pacific “ring of fire” is the area of ​​the planet where 90% of the earthquakes that occur in the world are concentrated, as well as a huge number of volcanoes, and includes highly seismic regions such as Japan, the West Coast of America, the Aleutians, the islands of Indonesia, and New Zealand.

Pacific Ring of Fire
The Pacific “ring of fire”, where 90% of the planet’s earthquakes and a huge number of volcanoes are concentrated.

Earthquakes with a magnitude greater than 9.0 after 1960

The 1960 earthquake was the most powerful ever recorded by humans, but in recent decades there have been other earthquakes of magnitude 9 or higher, As the of Sumatra (Indonesia) of 2004which caused a tsunami that left at least 230,000 dead (one of the great natural disasters of the modern era) and that of Japan in 2011, which again caused a terrifying tsunami that caused nearly twenty thousand deaths.