There are three ways to measure the magnitude of an earthquake. They are the Richter scale, the Moment Magnitude scale (MMS), and the Mercalli scale. The Richter scale was developed by Charles F. Richter in 1934 specifically for earthquakes occurring in California. It is used to rate the magnitude of an earthquake. By using a formula based on the largest wave recorded, calculations are made using a seismograph. In 1979, a more globally accepted measurement was adopted, the Moment Magnitude scale (MMS). This form of measurement takes recordings from several different seismograph stations and is based on the distance a fault moved and the force required to move it. Although it is very similar to the Richter scale, it provides broader accuracy, especially relating to events rating 8 or higher on the scale (UPSeis, n.d.). Giuseppe Mercalli invented the Mercalli scale in 1902. The Mercalli scale classifies earthquakes by their effect and impact using a twelve-point scale ranging from barely noticeable to severe damage. This method of measurement can vary widely depending on a variety of factors. For example, if an earthquake occurs in a heavily occupied area with lots of buildings, the damage may be more severe. However, if a strong earthquake occurs in an isolated area with few people and structures, the damage may be relatively low. In other words, the scale is subject to change depending on various factors. Whereas the MMS will assign a number to the occurrence that will only reflect the energy that was released from the earthquake, not the damage related to it or the impact it had on the area (UPSeis, n.d.).
Measuring earthquakes with a seismograph allows scientists to measure an earthquake's magnitude, the amount of energy it releases. Based on these findings, they are able to determine an earthquake's force, its focus-point or hypocenter underground, and its epicenter. The hypocenter or focus is where the earthquake truly begins. It is located at a tectonic plate boundary. The epicenter is located directly above the hypocenter on the Earth's surface. An earthquake is typically strongest at the epicenter. This is why the epicenter is the most accurate place to measure the magnitude of an earthquake.
To better understand the difference between the Richter scale and the MMS, watch the following video.
Measuring earthquakes with a seismograph allows scientists to measure an earthquake's magnitude, the amount of energy it releases. Based on these findings, they are able to determine an earthquake's force, its focus-point or hypocenter underground, and its epicenter. The hypocenter or focus is where the earthquake truly begins. It is located at a tectonic plate boundary. The epicenter is located directly above the hypocenter on the Earth's surface. An earthquake is typically strongest at the epicenter. This is why the epicenter is the most accurate place to measure the magnitude of an earthquake.
To better understand the difference between the Richter scale and the MMS, watch the following video.