The USA: Observing the Aftershocks of Massive 1800s Earthquakes

New Study suggests Previous Earthquakes Could be Aftershocks

Researchers from the University of Missouri and Wuhan University have recently conducted a study examining the relationship between seismic activity in the present-day United States and large earthquakes that occurred back in the 1800s. Their findings, published in JGR Solid Earth, indicate that the current seismic activity near the epicenters of historical quakes are likely aftershocks.

Aftershocks are a sequence of earthquakes that happen as the Earth’s crust adjusts following a major earthquake. By utilizing a statistical method, the researchers were able to differentiate between ongoing seismic activity and aftershocks of previous earthquakes.

The study specifically focused on three significant historical seismic events: the quakes in Quebec, Canada in 1663, the earthquake in Charleston, South Carolina in 1886, and the seismic activity along the Missouri-Kentucky border from 1811 to 1812.

Interestingly, the team discovered that up to 65% of the seismic activity recorded in the New Madrid seismic zone between 1980 and 2016 was likely aftershocks of the earthquakes that struck the area back in 1811-1812. This suggests that these historical earthquakes had a lasting impact on the region’s tectonic behavior.

Similarly, the aftershock activity from the 1886 Charleston earthquake in South Carolina remains significant and ongoing. This highlights the long-lasting effects that major seismic events can have on a particular area.

While the study provides valuable insights into the nature of aftershocks and their connection to previous earthquakes, Susan Hough from the US Geological Survey (USGS) cautions that the results still remain open to question. She suggests that tightly clustered earthquakes could have reasons beyond being aftershocks.

Nevertheless, the study contributes to a better understanding of seismic activity patterns, which ultimately aids in predicting the risk of future earthquakes in these regions. This research could prove indispensable in enhancing seismic hazard assessments and implementing more effective mitigation strategies.

As we delve deeper into the relationship between historical earthquakes and present-day seismic activity, scientists hope to gather more insights to ensure better preparedness and response measures in earthquake-prone zones.