What is an Earthquake?
An earthquake is a natural hazard where the Earth’s crust experiences intense shaking. This shaking can destroy buildings, damage infrastructure, and cause great loss of life. In coastal areas, earthquakes are capable of creating destructive waves called tsunamis, which can be even more dangerous than the actual quake. Earthquakes cannot be predicted. Geologists can often predict the likelihood of an earthquake occurring in an area, but not when it will occur. Because an earthquake could happen at any time, with no warning, it is important to be prepared for one. Fortunately, Massachusetts does not often experience large earthquakes. Compared to other parts of the United States and the world at large, Massachusetts has a low to moderate earthquake risk.
The History of Earthquakes in Massachusetts
Since records began in 1668, Massachusetts has experienced 408 earthquakes. In addition to these earthquakes, the state has been affected by earthquakes that originated in neighboring states. This may seem like a lot, but it’s important to remember that most of these earthquakes were small and caused little to no damage. Of the few serious earthquakes that Massachusetts has experienced, the most notable is the Cape Ann earthquake of 1755. The New Madrid earthquakes of 1811-1812, originated in Missouri, but caused widespread damage across much of the eastern US, including Massachusetts.
Cape Ann Earthquake
In 1755, a 5.8 magnitude earthquake struck about 30 miles east of Cape Ann, Massachusetts. Chimneys and walls were destroyed, and shaking was felt in the surrounding states. The earthquake was one of the strongest recorded in New England since records began. Geologists hypothesize that this earthquake was caused by stress in an ancient failed rift zone (an area where the crust used to be moving apart), but much remains to be learned about the exact causes of the quake.
New Madrid Earthquake
From 1811 to 1812, three major earthquakes occurred in Missouri, Arkansas, and Tennessee. Collectively, they have been dubbed the “New Madrid” earthquakes, after the town that was one of the closest to the epicenter of the quakes. Shaking from the initial 7.5 magnitude earthquake was felt in Boston, New York City, and Washington D.C. In addition to the three main earthquakes, the region also experienced several aftershocks, smaller earthquakes that followed the initial sequence. Although the shaking was powerful enough to ring church bells in Boston, there was little structural damage reported. Like the Cape Ann earthquake, the New Madrid earthquakes occurred within a tectonic plate, and were likely caused by stress at the site of an ancient rift zone.
Tips for Preparing for an Earthquake
- Develop an earthquake plan
- Speak to your family about what to do during an earthquake
- Discuss where to meet if an earthquake happens
- Secure dangerous items
- During an earthquake, top-heavy furniture like bookshelves and wardrobes is at risk of tipping over. Anchor objects to wall studs when possible, or move them to areas of your home where they pose less risk if they fall over.
- Water heaters, which are connected to both water and gas lines, could cause fire and/or flooding during earthquakes. Secure your water heaters with straps to reduce their movement.
- Secure any flammable or toxic materials that may be in your home.
If you leave near the coast, identify an area of high ground that you can evacuate to in the event of a tsunami.
Tips for Staying Safe During an Earthquake
- If you are inside a building:
- Take shelter under a table or other piece of furniture. If no shelter is available, move to a corner of the room and protect your head however you can.
- Stay away from glass, top-heavy furniture, and anything that could fall on you, like a light fixture or a picture frame.
- If you are in bed, stay there! Protect your head with a pillow.
- If you are outside:
- Get out in the open, away from buildings, streetlights, and vehicles.
- Remain outside until the shaking stops.
- If you are in a moving vehicle:
- Stop as quickly and safely as possible, and remain in your vehicle. If possible, avoid stopping near buildings, streetlights, trees, or other structures that may fall.
- Don't drive if conditions appear unsafe, even after the earthquake ends. Keep in mind that bridges and roads may have been damaged by the earthquake.
- If you live near the coast, get to high ground! Massive waves called tsunamis often follow earthquakes in coastal regions. A sign of an approaching tsunami is water receding from the beach.
Remain cautious, even after the shaking has stopped. Aftershocks (smaller earthquakes that occur after the initial quake) can sometimes occur and inflict additional damage. Additionally, items that were left unattended during the earthquake can also pose a danger. Ensure that no hot objects like stovetops or candles have set anything alight.
What causes earthquakes?
The outermost layer of Earth, the crust, is broken up into massive slabs of rock, called tectonic plates. The boundaries between these tectonic plates are where most earthquakes happen, as the plates slowly push, scrape, and slide past each other over millions of years. In the oceans, the sudden movement of rock caused by earthquakes can displace water, leading to destructive tsunami waves.
Massachusetts is not located on any plate boundaries (places where two or more tectonic plates meet). As such, typical plate boundary earthquakes are less likely to occur. However, earthquakes in the interior of tectonic plates, known as intraplate earthquakes, are still possible. Intraplate earthquakes tend to occur in areas of continental crust that have experienced consistent stress in the aftermath of ancient geological events like rifts and continental collisions.
The destructive power of an earthquake is measured by the Richter scale. The Richter scale is an important tool used by geologists for measuring the energy released by earthquakes, also known as the magnitude of the earthquake. The higher up on the Richter scale, the greater the magnitude, and the greater the damage. Earthquakes with a magnitude of 8 or 9 can cause incredible damage and be felt in multiple countries, but you might not even notice if a magnitude 1 earthquake is happening directly under your feet!
Additional Resources
How to prepare for earthquakes
https://www.usgs.gov/programs/earthquake-hazards/prepare
https://www.fema.gov/sites/default/files/2020-11/fema_protect-your-property_earthquakes.pdf
Learn more about Massachusetts’ earthquake risk
https://www.usgs.gov/programs/earthquake-hazards/science/introduction-national-seismic-hazard-maps
https://nesec.org/earthquakes-hazards/
https://earthquake.usgs.gov/earthquakes/eventpage/ushis7/region-info
https://nesec.org/massachusetts-earthquakes/
More information about what causes earthquakes
https://www.usgs.gov/programs/earthquake-hazards/science-earthquakes