Richter Scale:
The Richter scale is a logarithmic scale, created by Charles Francis Richter in 1935, as a mathematical device to compare the size of earthquakes. The scale gauges the magnitude of an earthquake using data recorded by seismograph stations across the world. The magnitude of an earthquake is determined by the logarithm of an amplitude of waves, with adjustments made for the location of the recorded data in relation to the epicenter.
On the Richter scale, the magnitude of an earthquake is expressed using either a whole number or a decimal (e.g. 3 or 8.1). Magnitudes of 2 and below are generally counted as 'microearthquakes' as they are generally not felt by people and only detected by sensitive instruments. A magnitude of approximately 5-6.9 is typically observed as a moderate to strong earthquake, whereas any earthquake with a magnitude of 7.0 or higher is regarded as a major earthquake.
Due to the logarithmic basis of the scale, each whole number in the scale is representative of a tenfold increase in the amplitude of an earthquake. As an approximation, each whole number releases 31 times more energy than is associated with the preceding whole number. This means, that as earthquakes are placed higher on the Richter scale, they are significantly larger and more damaging than the ones below it.
In Valdivia, the largest earthquake ever recorded was a 9.5 on the Richter scale, whereas more recent major earthquakes have been placed at approximately 8.8. When writing these measurements, the unit is often represented by Mw.
On the Richter scale, the magnitude of an earthquake is expressed using either a whole number or a decimal (e.g. 3 or 8.1). Magnitudes of 2 and below are generally counted as 'microearthquakes' as they are generally not felt by people and only detected by sensitive instruments. A magnitude of approximately 5-6.9 is typically observed as a moderate to strong earthquake, whereas any earthquake with a magnitude of 7.0 or higher is regarded as a major earthquake.
Due to the logarithmic basis of the scale, each whole number in the scale is representative of a tenfold increase in the amplitude of an earthquake. As an approximation, each whole number releases 31 times more energy than is associated with the preceding whole number. This means, that as earthquakes are placed higher on the Richter scale, they are significantly larger and more damaging than the ones below it.
In Valdivia, the largest earthquake ever recorded was a 9.5 on the Richter scale, whereas more recent major earthquakes have been placed at approximately 8.8. When writing these measurements, the unit is often represented by Mw.
The Modified Mercalli Scale
The modified Mercalli scale is another way of categorising earthquakes, however this scale is based on intensity and what is felt during and after an earthquake. It was created in 1931 by American seismologists Frankneumann and Harry Wood, and is currently used as the official American earthquake intensity ranking system.
The intensity of an earthquake is determined by several key reactions, as well as structural damage caused by the quake. The scale is comprised of increasing levels of intensity, ranging from undetectable shaking to severe structural damage and landscape alterations. The scale is measured in Roman numerals and, unlike the Richter scale, does not have a mathematical basis. Instead, it ranks earthquakes based on observed effects.
The lowers numbers on the scale generally refer to what is experienced by the people in the earthquakes, whereas the higher numbers are based upon structural damage.
In Valdivia, the majority of the cities high-magnitude earthquakes have been placed at an IX or larger. The Mercalli scale does not directly respond with the Richter, however they can be loosely compared and evaluated together.
The intensity of an earthquake is determined by several key reactions, as well as structural damage caused by the quake. The scale is comprised of increasing levels of intensity, ranging from undetectable shaking to severe structural damage and landscape alterations. The scale is measured in Roman numerals and, unlike the Richter scale, does not have a mathematical basis. Instead, it ranks earthquakes based on observed effects.
The lowers numbers on the scale generally refer to what is experienced by the people in the earthquakes, whereas the higher numbers are based upon structural damage.
In Valdivia, the majority of the cities high-magnitude earthquakes have been placed at an IX or larger. The Mercalli scale does not directly respond with the Richter, however they can be loosely compared and evaluated together.