When the 4.4-magnitude earthquake hit the Los Angeles area on Monday afternoon, residents reported feeling a prolonged quake with significant shaking. However, the magnitude of an earthquake is not the only factor that determines how it is felt on the surface of the Earth, as explained by Richard Allen, the director of the University of California, Berkeley Seismology Lab.
Magnitude is a measure of an earthquake’s strength and is often expressed using the Richter Scale. Larger earthquakes that last longer have higher magnitudes compared to smaller, shorter ones. The proximity to the epicenter of an earthquake plays a significant role in determining the intensity of the shaking experienced.
Despite this general rule, some higher magnitude earthquakes may have the most intense shaking along the fault line where the earthquake originates. This means that two individuals at the same distance from the epicenter may feel different intensities of shaking if only one of them is near the fault line. Additionally, the type of building you are in during an earthquake can also affect the level of shaking experienced. One- or two-story buildings amplify seismic shaking slightly, while taller buildings and skyscrapers absorb more of the quake’s energy and may sway back and forth.
The composition of the soil and rocks beneath an individual can also influence how strong an earthquake feels. Those living in areas with soft soils, such as sedimentary basins, experience more powerful shaking because the soil amplifies the seismic waves. Conversely, individuals located on harder rocky surfaces may feel a weaker quake due to the different properties of the ground.
The nature of seismic waves can also impact how an earthquake is perceived. P waves, which are the first waves to emerge from an earthquake, are often high-frequency and can result in abrupt shaking. On the other hand, S waves that follow are characterized by more gradual oscillations, giving rise to a rolling sensation. Those closer to the epicenter of an earthquake typically feel the intense P waves, while those further away may only experience the slower-traveling S waves.
In conclusion, the intensity and nature of shaking experienced during an earthquake are influenced by various factors such as magnitude, distance from the epicenter, building structures, soil composition, and the type of seismic waves. Understanding these elements can help individuals better prepare for and respond to seismic events in their area.
