4.8 Magnitude Earthquake Shakes Northeast, Explained By USGS

• Shallow earthquakes cause more intense shaking at the surface.

• Eastern US rocks are older, denser, and better at transmitting seismic energy.

• Older buildings in the Northeast may not be designed to withstand earthquakes.

A preliminary 4.8 magnitude earthquake centered in northern New Jersey on Friday sent shockwaves across hundreds of miles of the Northeast, affecting regions from Washington, DC, to New England. The US Geological Survey attributes the widespread impact of the quake to several factors.

The earthquake was relatively shallow, occurring just 5 km beneath the Earth's surface. Shallow earthquakes, defined as those between 0 to 70 km deep, tend to produce more intense shaking at the surface compared to deeper ones of the same magnitude due to the shorter distance for energy to travel.

The geology of the eastern US also contributes to the quake's reach. The rocks in this region are older, denser, and harder than those in the West, making them more efficient conduits for seismic energy. This allows the energy released by an earthquake to travel over longer distances in a more potent form.

Another factor influencing the impact of the earthquake is the age of buildings in the Northeast. Older structures, particularly shorter buildings like houses, may not be designed to withstand the intensity of seismic activity. The USGS warns that earthquakes in the East tend to have a faster back-and-forth motion, which can put smaller buildings at greater risk of damage.

The recent earthquake serves as a reminder of the complex interplay between geology, building codes, and seismic activity in the Northeast. While the region may not experience frequent earthquakes, events like these highlight the importance of preparedness and understanding the unique geological characteristics that can amplify the effects of seismic events.