An earthquake shook much of the northeast Friday morning, with tremors felt throughout the New York metropolitan area and in the communities of Baltimore And Philadelphia through New England.
The earthquake had a magnitude of 4.8, according to the US Geological Survey. No major damage was reported as of midday Friday, authorities said.
Here’s how seismic force is measured and what different earthquake magnitudes mean.
How are earthquakes measured?
Earthquakes are recorded by a network of seismic stations that measure ground movement, according to the USGS. Each station captures data on the amount of movement and vibration of the Earth during an earthquake and the amount of energy that escapes from the hypocenter, or the site of an earthquake below the surface of the planet.
Several scales are used to measure an earthquake. Most often, scientists refer to the magnitude of an earthquake as a measure of its strength. Geologists once used the Richter scale, but this measurement is considered obsolete and is no longer used. An earthquake can also be described by its intensity, or by the extent of shaking and damage caused by the earthquake.
USGS
What is the magnitude scale of earthquakes?
The magnitude scale is the most common way to measure the size of an earthquake. The USGS uses the moment magnitude scale to measure earthquakes.
“Moment” is a physical quantity proportional to the slip on a fault line multiplied by the area of the fault that slipped, the USGS said. The moment can be estimated from seismograms and other geological measurements. The moment number is then converted to a scale number, which provides an estimate of the size of the earthquake.
Increasing by a whole number on the scale indicates that the ground motion recorded by the seismic equipment has increased by a factor of 10. This means that a magnitude 5 earthquake would result in approximately 10 times more ground motion than an earthquake magnitude 4, according to the Ministry of the Environment. Geological Mining Engineering and Sciences at Michigan Technological University.
The scale has no upper limit, but no faults long enough to generate a magnitude 10 earthquake are known, according to the USGS.
In some cases, earthquakes can be so small that they have negative magnitude, the USGS explains.
What is the Richter scale and why is it obsolete?
The Richter scale is an older method once used to describe the size of earthquakes. The scale was developed by Charles Richter in the 1930s, but the USGS says it only worked well over certain frequency and distance ranges. New scales have been created to take into account earthquakes outside these ranges.
However, each scale had its limitations, so the moment magnitude scale was developed as a more thorough and uniformly applicable measure for earthquakes.
What is the most powerful earthquake ever recorded?
The most powerful earthquake ever recorded occurred in Chile in 1960. This “megaquake” had a magnitude of 9.5 and occurred on a fault line a thousand kilometers long.
This earthquake lasted more than 11 minutes and triggered tsunamis around the world. The town of Valdivia was the hardest hit area, which is why the earthquake is sometimes known as the Valdivia earthquake.
Two million people were left homeless, according to the National Geographic Society. Around 1,655 people were killed in the first earthquake and 3,000 people were injured. The highest tolls include those killed in tsunamis.
The most powerful earthquake in United States history was the 9.2 magnitude Great Alaska Earthquake of 1964, which also triggered a tsunami.
So, is today’s 4.8 magnitude earthquake considered significant?
An earthquake of magnitude 2.5 or less is usually not felt, but can be recorded by a seismograph, according to the Department of Engineering and Geological and Mining Sciences at Michigan Technological University.
Earthquakes ranging from 2.5 to 5.4 are felt, but cause only minor damage in most cases. This is the beach where this earthquake in the northeast falls, and no significant damage or injuries have been reported so far. At a magnitude of 4.8, it was one of the strongest earthquakes felt in the region in the last century, but it is not a record. A magnitude AA 5.0 earthquake was measured in New York in 1884, and in 2011 a 5.8 earthquake was concentrated in Virginia and shook the whole east coast.
Earthquakes with a magnitude of 5.5 to 6.0 can cause damage.
Earthquakes with a magnitude between 6.1 and 6.9 can cause “a lot of damage in highly populated areas,” while a quake with a magnitude of 7.0 to 7.9 is considered an earthquake major causing serious damage. Next comes an earthquake of magnitude 8.0 or greater, considered a massive earthquake with the potential to “totally destroy communities” near its epicenter.
No tsunami activity is expected due to today’s earthquake, and the possibility of aftershocks remains low, officials said.
Kerry Breen
Grub5
