# Why are there earthquakes in the middle of the North American plate? **URL:** \ **Category:** Factual Questions\ **Created:** [April 5, 2024, 4:48pm UTC](https://boards.straightdope.com/t/why-are-there-earthquakes-in-the-middle-of-the-north-american-plate/999887 "2024-04-05T16:48:19Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Measure\_for\_Measure](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/measure_for_measure/32/557_2.png) [@Measure\_for\_Measure](https://boards.straightdope.com/u/Measure_for_Measure)\ **Post date:** [April 5, 2024, 4:48pm UTC](https://boards.straightdope.com/t/why-are-there-earthquakes-in-the-middle-of-the-north-american-plate/999887/1 "2024-04-05T16:48:19Z")
Plate tectonics posits that earthquakes arise from plates rubbing against one another, or moving under one another. New Jersey recently had an earthquake. In 1755 there was an estimated magnitude 6.0 tremblor just outside of Boston, MA. The northeastern United States is located in the middle of the North American plate. So why are there earthquakes outside of major fault zones? Here’s a link to a map of earthquakes in the northeast from 1975-2017. They are small, but there are a lot of them, scattered throughout the region. I see a few larger ones on both sides of the St Lawrence River. [https://nesec.org/massachusetts-earthquakes/](https://nesec.org/massachusetts-earthquakes/) (I assume the answer involves smaller plates, but I didn’t locate a good treatment of that hypothesis on the web.) #geology ---
**Author:** ![Moriarty](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/moriarty/32/49_2.png) [@Moriarty](https://boards.straightdope.com/u/Moriarty)\ **Post date:** [April 5, 2024, 5:38pm UTC](https://boards.straightdope.com/t/why-are-there-earthquakes-in-the-middle-of-the-north-american-plate/999887/2 "2024-04-05T17:38:06Z")
> [@Measure\_for\_Measure](#): > > So why are there earthquakes outside of major fault zones? Apparently, earthquakes on the East coast can be felt _farther away_ than western earthquakes. > [@](#): > > The Earth’s crust beneath the Eastern U.S. iolder and colder" than out West. The fault lines are more healed. As a result, the East is far less seismically active – but when earthquakes do hit, that hard ground is far more effective and conducting the seismic waves. > > “When you hit it, it rings like a bell,” said Christopher Scholz a professor of geophysics at Columbia University’s Lamont-Doherty Earth Observatory at Columbia University. “Even with a 5.9 you just feel it for a long, long way. There’s nothing to slow that wave down.” > > In the West, where the earth is newer and more faulted, it’s more like hitting a brick. “When you get an earthquake it’s sort of like a thud. The waves don’t propagate as far,” Scholz said. > **[Why are East Coast earthquakes so widely felt?](https://www.cbsnews.com/news/why-are-east-coast-earthquakes-so-widely-felt/)** > > The harder earth beneath the Eastern Seaboard conducts seismic energy much faster and farther than in quake-prone California ---
**Author:** ![Measure\_for\_Measure](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/measure_for_measure/32/557_2.png) [@Measure\_for\_Measure](https://boards.straightdope.com/u/Measure_for_Measure)\ **Post date:** [April 5, 2024, 6:13pm UTC](https://boards.straightdope.com/t/why-are-there-earthquakes-in-the-middle-of-the-north-american-plate/999887/3 "2024-04-05T18:13:01Z")
Nonetheless, the epicenter of the recent New Jersey earthquake was near Lebanon, New Jersey, closer to Pennsylvania than the Atlantic Ocean. The seismically active Mid-Atlantic ridge runs down the center of the Atlantic, over 1000 miles away. My link shows epicenters scattered around the Northeast, extending to the Great Lakes region. Frederik J. Simons, a professor of geosciences at Princeton University tells NBC news that the latest earthquake occurred in the Ramapo fault system, “a boundary where the continental and oceanic tectonic plates meet and are stuck together.” That explanation puzzles me, as the epicenter was fairly far inland. Cite: [Earthquake shakes U.S. East Coast, impacting New York, Pennsylvania, New Jersey and others](https://www.nbcnews.com/science/science-news/earthquake-shakes-us-east-coast-rcna146575) ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [April 5, 2024, 6:26pm UTC](https://boards.straightdope.com/t/why-are-there-earthquakes-in-the-middle-of-the-north-american-plate/999887/4 "2024-04-05T18:26:12Z")
The general answer is: tectonic plates stretch and squeeze more than you might think. Most plates, for example, are moving in a somewhat different direction one one side than on the other – so, there must be some mid-plate stretching and squeezing going on. ---
**Author:** ![flurb](https://avatars.discourse-cdn.com/v4/letter/f/51bf81/32.png) [@flurb](https://boards.straightdope.com/u/flurb)\ **Post date:** [April 5, 2024, 6:26pm UTC](https://boards.straightdope.com/t/why-are-there-earthquakes-in-the-middle-of-the-north-american-plate/999887/5 "2024-04-05T18:26:57Z")
> [@Measure\_for\_Measure](#): > > The northeastern United States is located in the middle of the North American plate. So why are there earthquakes outside of major fault zones? Faults don’t only occur at plate boundaries. Intraplate faults are less common but can exist where there’s a failed rift or partial fracture within a continental plate that is subject to tectonic strain. The New Madrid fault system is a prominent example. > **[New Madrid Seismic Zone](https://en.wikipedia.org/wiki/New_Madrid_Seismic_Zone)** > > The New Madrid Seismic Zone (NMSZ) (/ˈmædrɪd/), sometimes called the New Madrid Fault Line, is a major seismic zone and a prolific source of intraplate earthquakes (earthquakes within a tectonic plate) in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri. > The New Madrid fault system was responsible for the 1811–12 New Madrid earthquakes and has the potential to produce large earthquakes in the future. Since 1812, frequent smaller earthquakes have be...