# Richter scale of an earthquake

Every time there is an earthquake on the news you may hear about its magnitude in a “Richter scale”, and perhaps in terms of intensity of shaking in the “Mercalli scale,” which are the two perspectives of measuring the energy of an earthquake.

Richter scale is used to describe the approximate amount of energy which is released in an earthquake (the earthquake magnitude) that propagates through the ground. This quantity is measured using seismometers observations.

The Richter scale is “logarithmic”. This means to say that an earthquake scale 6 is 10 times more powerful than a 5 scale earthquake.

*Note of this post: *

*TNT equivalents are estimated considering that the said explosive discharge is done below the surface, within the crust.**Equivalents with respect to objects thrown from different heights consider an acceleration of 9.81 m/s2 gravity constant (although the gravitational acceleration varies with respect to distance from the center of**the Earth)**It is very important to note that energy equivalents are considered just in the place where the earthquake occurs, and that the energy released during an earthquakes dissipates through matter and is felt at different accelerations depending on the distance to the epicenter and hypocenter.*

Earthquakes of magnitude Richter scale 1 would be the equivalent of 2 MegaJoules, or a small explosion at a construction site or the use of 480 g of TNT.

Earthquakes between 2 and 2.9 usually occur around 350,000 each year and usually are not noticeable. The earthquake of 2.5 Richter scale, would be equivalent to 360 MegaJoules or the explosion of a butane tank or use of 85 kg of TNT. Usually there are around 3 million earthquakes of 2.5 each year on Earth, but are imperceptible thus they are called “microearthquakes”.

**We estimate that an earthquake of magnitude 2.5 on the Richter scale would be the equivalent of energy that would have an iron object of 45 cm of diameter thrown from a height of 100 km in the mesosphere just before it hits the Earth’s lithosphere.**

Earthquakes between 3 and 3.9 of Richter scale earthquakes usually occur around 49,000 each year on Earth’s crust, often noticeable but which rarely cause damage. Earthquakes of magnitude 3.5 are equivalent to 11 gigajoules, considered weak and equivalent to the explosion of a gas plant and have the energy equivalent to use 2.7 tons of TNT.

**We estimate that an earthquake of 3.5 magnitude on the Richter scale would be the equivalent of energy that would have an iron object of 1.4 meters of diameter thrown from a 100 km altitude in the mesosphere just before it hits the Earth’s lithosphere.**

Normally occur on Earth around 6200 earthquakes between 4 to 4.9 magnitude on the Richter scale, generating movement in rooms but unlikely damage. The earthquake of 4.3 degrees will not cause damage, and is the equivalent of 180 GJ of energy, which is also equivalent to use 43 tons of TNT at the same instant, or approximate the energy of a tornado.

**We estimate that to happen an earthquake of 4.3 magnitude on the Richter Scale would be the energy equivalent to toss an iron object of 3.6 meters of diameter from 100 km altitude in the mesosphere just before it hits the Earth’s lithosphere.**

When an earthquake is greater than 5 degrees on the Richter scale, it will be reported worldwide, whereas less than 5 degrees earthquake are used nationally for monitoring.

The earthquakes of magnitude between 5 to 6 degrees on the Richter scale will cause slight damage to buildings and other deficient structures within 10 km from its epicenter. Normally there are nearly 800 each year on Earth. The earthquake of 5.5 degrees are equivalent in energy to the use 2700 tons of TNT exploding at the same instant, an energy of 11 TeraJoules.

**We estimate that an earthquake of 5.5 degrees on the Richter scale would be the equivalent of energy that would have an iron object with a diameter of 13.9 meters tossed from a 100 km altitude in the mesosphere just before it hits the Earth’s lithosphere.**

Earthquakes between 6 degrees and 7 degrees (equivalent to 199,000 tons of TNT) on the Richter scale will cause severe damage in areas where many people live. Usually there are around 120 of this type of earthquakes each year. The earthquake of 6.5 degrees are equivalent energy use 85 000 tons of TNT or 360 TeraJoules.

The earthquake of 6.5 degrees on the Richter scale are equivalent energy to use 85,000 tons of TNT at the same instant or 360 TeraJoules. **We estimate that this energy would be the equivalent of tossing an iron of a diameter of 44.8 meters from a 100 km altitude in the mesosphere just before it hits the Earth’s lithosphere.**

Those earthquakes above the 7.1 scale potentially cause serious damage over large areas in a radius of up to 100 km depending on their depth. Usually there are around 18 each year on Earth. An earthquake of 7.5 magnitude is equivalent to the energy of using 2.7 million tons of TNT at the same instant or 11 petajoules.

The earthquake of 8.1 magnitude in the Richter scale (which are equivalent to use 16.46 million of tons of TNT at the same instant), were recorded for example in the 1985 earthquake in Mexico City. It normally once a year on Earth.

The earthquake of 8.5 degrees are equivalent to the energy released at a detonation of 85 million tons of TNT at the same instant, or 360 petajoules. **We estimate that it would be the equivalent of energy generated by a iron object of 447 meters in diameter tossed from a 100 km altitude in the mesosphere just before it hits the Earth’s lithosphere.**

Historically the largest earthquakes are slightlyof magnitudes above 9.0 (equivalent to using 32 billion tons of TNT at the same instant), but there is actually no limit to the magnitude of an earthaquake. Normally one of these earthquakes happen every 20 years and can be classified as “devastating” in areas of several thousand kilometers from the epicenter.

The largest earthquake recorded in modern history was 9.5 degrees in 1960 in Valdivia, Chile (equivalent to using 2.7 billion tons of TNT or 11 exajoules). **We estimate that this is equivalent to the energy released by tossing an iron object of 1.4 km of diameter from a 100 km altitude in the mesosphere just before it hits the Earth’s lithosphere.**

An earthquake of 12.5 magnitude in the scale of Richter would be the equivalent energy caused the meteorite impact on Earth in the Yucatan Peninsula 65 million years ago (would be equivalent to using one trillion tons of TNT, or approximately 420 ZetaJoules). **We estimate that it would be the equivalent of energy generated by an iron object of 47 km of diameter tossed from an altitude of 100 km in the mesosphere just before it hits the Earth’s lithosphere**