In a new study, scientists have discovered that the earthquakes which have been occurring in modern times in the United States could be the aftershocks of quakes that have been happening since the 1800s.
To come to their conclusions, the study examined 87 earthquakes that have hit the Western US in recent years. The data shows that these quakes were centered around a particular region known as the Cascadia Subduction Zone, which is the boundary location between the North American Plate and the Juan de Fuca Plate.
Researchers compared data from the Cascadia Subduction Zone to catalogs from the early 1800s that showed strong seismic activity in the area. They then matched the geographic location and size of the quakes to the current seismic data.
The researchers found that the current quakes in the Cascadia were most likely aftershocks of quakes which have occurred hundreds of years ago. The aftershocks would be, on average, a magnitude 6.7 which is significant when compared to the magnitude 5.0+ quakes that have been occurring in modern times.
This means that the seismic activity since the 1800s could have been occurring in the same region, and the recent quakes are just magnified versions of what was happening in the past.
In regards to the risk that exists for people living around the Cascadia Subduction Zone, the study shows an increase in the amount of tremors. Although this is concerning, the researchers say there is no need to panic as the quakes are small and pose no significant threat.
Overall, this study is a great example of how seismologists are using historical data to better understand our current seismic landscape. By understanding the patterns of quakes that have happened in the past, scientists can better use data to help predict and better prepare for possible quakes in the future.