During the discussion of earthquakes, many questions arise, but few of them are completely hypothetical. For example, recently the scientific community tried to find an answer to the question of whether an earthquake could be strong enough to destroy the planet.
The question turned out to be extremely difficult and required a lot of work.
Various causes of earthquakes
To begin with, it's worth talking about what causes earthquakes and how strong they can be.
In fact, there are a relatively large number of reasons that cause earthquakes on the Earth's surface, among them there may even be the gravitational attraction of the Moon. However, for the sake of simplicity and effectiveness of our hypothetical apocalyptic scenario, it is worth focusing on two main causes of seismic activity.
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Most earthquakes occur at the boundaries of tectonic plates, in the area of tectonic or geological faults.
Tectonic shifts
For example, the San Andreas Fault, which is a transform right-sided fault. Because of this, destructive, but shallow earthquakes occur in the region. A transform fault means that tectonic plates do not move against each other, but along it, without creating a new earth's crust or destroying the old one.
Geological faults are not always transformable. Sometimes, two tectonic plates move directly on top of each other and collide along a convergent fault line. There are two types of convergent fault: subduction and collision.
Convergent boundaries
Subduction occurs as a result of the collision of an oceanic lithospheric plate with a continental one, or when two oceanic plates collide. The result of subduction is that one slab practically "crawls" onto another. The dense crust of the lower plate (oceanic) dissolves into the mantle, while the continental plate remains on top. The active zone of the continental margin is the Andean coast of South America.
When two oceanic plates collide, an island arc is formed as a result of subduction, that is, an island grows, which does not always appear above the water surface. The Kuril Islands are an example of a modern island arc.
Collision occurs when two continental plates collide and is an orogeny process. Active mountains - Himalayas.
As a result of both processes (both subduction and collisions), deep earthquakes arise that can cause destruction not only in the fault region, but also far beyond its boundaries.
How strong can earthquakes be?
Here are the five largest earthquakes recorded in the last hundred years:
- Earthquake in Kamchatka with a magnitude of 9.0, which occurred in November 1952. As a result of this earthquake, caused by the convergent border of two plates in the Pacific Ocean, a huge tsunami was formed, which destroyed several settlements in the Kuril Islands and Kamchatka.
- The East Japan earthquake of magnitude 9.1, which occurred in 2011 and entailed one of the most destructive tsunamis in human history, killing 20 thousand people.
- An earthquake in Alaska with a magnitude of 9.2, which occurred in the spring of 1964. Due to the fact that the region was not densely populated, even despite the strongest tsunami, only about 30 people were affected.
- The earthquake in the Indian Ocean with a magnitude of 9.3, which occurred in 2004 and had a devastating impact on Indonesia. The tsunami killed nearly a quarter of a million people.
- The great Chilean earthquake of 1960 with a magnitude of 9.5 was not only the cause of the strongest destructive aftershocks, but also entailed a huge tsunami that engulfed almost the entire Pacific coast.
Measuring the strength of an earthquake
Most of us are only familiar with the Richter scale, which measures the strength of an earthquake in relation to the amplitude of the tremors. The higher the amplitude, the stronger the earthquake. Despite the popularity of the Richter scale, since 1970 it has been replaced by a more accurate magnitude scale based on seismic moment.
With new measuring instruments and quantities, seismologists can use the seismic waves of an earthquake to measure the amount of energy released by the collision of lithospheric plates.
For example, as a result of the Chilean earthquake, 8.3 quintillion joules of energy were thrown out in a few seconds. This is 42 times more than in the explosion of the most powerful known thermonuclear explosive device (Tsar Bomba).
The power of mega jerks
If you carefully study the five strongest earthquakes listed above, it turns out that they all occurred along the convergent boundaries of lithospheric faults.
It is almost impossible to describe these earthquakes in relation to their destructive effect. The release of such a huge amount of energy led to the fact that the soil practically floated right under our feet, washing away and carrying away entire cities and settlements.
These earthquakes turned out to be so strong that they affected the length of the day and night, as the planet moved slightly off its axis.
Theoretical model
However, scientists argue that even such a massive release of energy will not be enough to destroy the planet. None of the above earthquakes could even split the earth's firmament, not to mention the mantle, which is almost impossible to split due to its density and high pressure.
In theory, it is possible to imagine an earthquake capable of splitting the Earth into pieces. You just need to calculate how much energy is required for this.
Mega shock earthquakes, especially deep ones, release energy due to friction of lithospheric plates. Assuming that the earth's solid is mostly granite, which melts at 1,260 ° C, it takes very little physical knowledge to come to a conclusion on how much energy can “tear” the earth apart. The ejection of a mega-earthquake should be 4.4 x 1023 joules, which is 53 thousand times stronger than the strongest earthquake recorded by man.
Hypothetical results
If such an earthquake were possible, it would dramatically affect the future of the planet. For example, a jolt of such force would throw the planet out of its usual orbit around the sun, forever changing the seasons.
The molten earth's crust, if dropped into water, would cause an incredible release of hot steam that could wipe out all living things in the region.
Fortunately, an earthquake of this magnitude cannot happen on Earth, since it is physically impossible. There are no solid minerals on the planet that would withstand such mechanical stress. This means that tectonic plates begin to move towards each other long before enough energy is generated to destroy the earth's crust.
Hope Chikanchi