Earthquakes are considered among the most powerful natural disasters on Earth. An earthquake occurs when energy stored within the Earth’s crust is suddenly released, creating seismic waves that cause the ground to shake. To evaluate the strength and impact of an earthquake, scientists and researchers use seismic scales to calculate the damage. These seismic scales help authorities assess destruction, issue warnings before subsequent disasters and improve preparedness for public welfare.
What Is a Seismic Scale and How Does It Help?
A seismic scale is a system used by scientists to measure the size, strength, and effects of an earthquake. Different scales are used depending on whether researchers want to measure the physical energy released by the earthquake or the actual level of damage it has caused. The two scales most commonly referenced during an earthquake are the Richter Scale and the Moment Magnitude Scale
While the Richter Scale was widely used in the past, the Moment Magnitude Scale is now considered the global standard because it is much more accurate for measuring modern earthquakes. Unlike older methods, the Moment Magnitude Scale calculates the total energy released by looking at factors such as the size of the fault rupture, the amount of physical movement along the fault, and the rigidity of the rocks involved.
How Are Earthquakes Measured?
Earthquakes are measured using instruments called seismometers or seismographs. These devices detect and record the seismic waves that travel through the Earth during a quake. When an earthquake occurs, seismic waves spread outward from the epicenter. Seismographs record these waves, allowing scientists to analyze the wave patterns, travel times, and other core measurements. This data is then used to calculate the earthquake’s precise magnitude and location. Today, modern seismic networks around the world provide real-time earthquake monitoring and power early-warning systems.
Measuring Earthquake Effects
While magnitude measures the energy at the source, scientists measure the localized effects of an earthquake using the Modified Mercalli Intensity (MMI) Scale. Instead of calculating energy, the MMI scale determines intensity based on what people actually feel and the visual damage caused to buildings and infrastructure. The MMI scale ranges from roman numerals I (Not Felt) to XII (Total Destruction). This helps emergency authorities understand exactly how communities are affected, which is crucial for directing rescue and relief efforts.
