Earthquakes have always been one of the most shocking and destructive natural phenomena that our planet can experience. Throughout history, they have left an indelible mark on the lives of many people. Their study has allowed the development of techniques to measure their magnitude and better understand their behaviour. But what has been the strongest earthquake ever recorded?
To answer this question, it is essential to understand how earthquake measurement scales work and what factors determine the power of an earthquake. In this article, we will explore the key concepts, the tools used to measure them, and some of the most devastating seismic events that have ever shaken the Earth.
How do earthquakes occur?
Earthquakes are caused by the sudden release of Energy in the earth's crust due to the movement of tectonic plates. When these plates move, they can generate friction and tension that, when released, cause seismic waves that spread through the soil.
There are several types of geological faults where these movements can occur:
- Normal faults: They are generated when one plate slides downward relative to another.
- Reverse faults: The opposite movement occurs, where one plate rises above another.
- Strike-slip faults: Here the plates move horizontally relative to each other.
An emblematic case is the Falla de San Andres in California, which has been the source of numerous earthquakes throughout history.
Instruments for measuring earthquakes
To quantify the power of an earthquake, seismologists use various tools and scales. One of the most important devices is the seismograph, which records ground vibrations and allows the magnitude of the event to be determined.
In addition to seismographs, other complementary instruments are used such as:
- Accelerometers: They measure the acceleration of the ground during an earthquake.
- Advanced GPS systems: They detect displacements generated by the movement of the plates.
These devices allow you to obtain accurate data to better understand the behavior of earthquakes.
Earthquake measurement scales
To classify the strength of earthquakes, have been developed different scales:
Richter scale
Created in 1935 by Charles Richter, this scale quantifies the magnitude of an earthquake by measuring the amplitude of seismic waves on a seismograph. It is based on a logarithmic scale, meaning that each whole number represents a tenfold increase in the energy released. To understand the relationship to historical events, one can look at how these large earthquakes influenced the elastic properties of the crust, as explained in changes in the elasticity of the crust after large earthquakes.
Moment Magnitude Scale
This modern scale assesses the total amount of released energy by an earthquake. Unlike the Richter scale, it is more accurate for large earthquakes and is used as the current standard in seismology. The history of the most powerful earthquakes is also studied using this scale, as in the impact of earthquakes in Burma.
Mercalli scale
Unlike the previous ones, the Mercalli scale measures the intensity of an earthquake based on the effects perceived by people and the structural damage. It is expressed in Roman numerals from I to XII, where a level of I is practically imperceptible and a XII implies total destruction.
The most powerful earthquakes in history
Over the years, devastating earthquakes have occurred that have changed the geography and history of many regions. Some of the most impactful include:
- Valdivia earthquake, Chile (1960): With a magnitude of 9.5, it was the strongest on record. It triggered a tsunami that affected multiple Pacific countries, and its study is essential to understanding the .
- Alaska earthquake (1964): It reached magnitude 9.2 and generated large landslides and tsunamis. The moment magnitude scale helps compare them.
- Sumatra earthquake (2004): With a magnitude of 9.1, it caused a tsunami that left more than 230.000 victims, making it one of the most devastating in history.
The Volcanoes have also influenced seismic activity throughout history, since eruptions can generate very intense earthquakes.
When should we be concerned about the magnitude of an earthquake?
Depending on their strength, earthquakes can go unnoticed or cause a massive destructionThey can be classified as follows:
- Less than 2.0: Not perceptible to humans.
- Between 3.0 and 4.9: Slightly perceived, but no serious damage.
- From 5.0 to 6.9: They can cause structural damage in weak buildings.
- From 7.0 onwards: The damage is severe and affects a wide area.
Starting at magnitudes greater than 8.0, earthquakes have devastating reach and can change the geography of the affected areas. For example, Earthquake in Nepal predicted by scientists exemplifies how studies in prediction help to reduce its effects.
Earthquakes remain a fascinating but dangerous natural phenomenon. Understanding how they work, how they are measured, and which have been the most intense in history helps us to be better prepared for possible future seismic events. Thanks to science and technology, we are making more progress every day in predicting and preventing these phenomena that have changed the course of humanity.
