From where

First of all, it is necessary to understand how normal earthquakes occur along boundary lines. More earthquakes occur in these regions because the Earth’s interior, its mantle, moves the planet’s tectonic plates, causing them to split and collide. The cracks called faults between these plates are fragile. So when stress begins to build up at these weak points, the plates can break apart and shake the planet. This is what we feel as an earthquake.

However, from time to time, a shock can also occur in the middle of a tectonic plate. Scientists call this an intra-plate earthquake. Exactly why this happens remains a big mystery, says geophysicist Christine Powell of the University of Memphis. He and other scientists studied places where intra-plate earthquakes are concentrated, called intra-plate seismic zones. Such regions exist, for example, in parts of the central and eastern United States. After researching these areas, Experts have several theories as to why it can appear in such unexpected places..

first idea

One possible explanation is that intraplate earthquakes may originate from ancient glaciers, as a 2001 study showed.

About 20,000 years ago, much of North America was covered by a giant ice sheet and the land was under heavy load. As the ice sheet melted, the land gradually rose, so earthquakes may be the result of this rearrangement. In fact, once the pressure is removed the shell relaxes and gradually returns to its normal shape.

But there is little evidence to support this theory. The orientation of the earthquake axis and the glacier location do not coincide.

friend’s idea

Another idea is that intraplate earthquakes occur in the interior of tectonic plates around old faults that have grown over a long period of time. Because these “scars” are deep underground, we cannot see them.

Over billions of years, the earth’s crust split and reassembled, leaving traces of ancient faults. When pressure waves propagate deeper into the plates, they put so much pressure on these old faults that they can reactivate even if they don’t separate again.

third idea

The complex composition of the Earth’s crust and subsurface may also be a factor. Sometimes ancient rock debris gets stuck in the middle of the plate, causing instability, according to a 2007 study published in the journal Geophysical Research Letters. Pipes with hot flows can create additional pressure, causing movement on the planet’s surface.

fourth idea

Fracking, the process of pumping water, sand and chemicals into underground rocks to extract oil or gas, can also trigger earthquakes. Wastewater from these operations is pumped into deep wells that can seep into fractures, lubricate old faults and trigger seismic activity, according to a 2013 review published in the journal Science. For example, fracking was linked to a series of earthquakes in Ohio in 2015.

Research

Scientists are trying to better understand these processes through projects such as EarthScope, which uses sensors to record dynamics beneath the Earth’s crust. When it first started, some scientists didn’t think the sensors would find anything that could cause an earthquake. However, the program was successful.

Understanding intraplate earthquakes is important because they pose a significant risk to people living in these seismic zones. Largely because no one expected and prepared for possible earthquakes in certain parts of the planet.