Earthquakes are usually considered natural disasters, but a recent study shows that earthquakes caused by humans are the next biggest problem we are about to face.
Digging mines can cause earthquakes between magnitude 3 and magnitude 5. According to the Human-Induced Earthquake Database, there have been 728 earthquakes or sequences of earthquakes that may have been set off by human activity over the past 149 years. Most of them were small, between magnitude 3 and magnitude 4, but the list also includes several large, destructive earthquakes, such as the magnitude 7.8 quake in Nepal in April 2015, which one paper linked to groundwater pumping.
According to a BBC article, Miles Wilson, a hydrogeologist at Durham University, his colleagues say that HiQuake (Human-Induced Earthquakes) is the biggest, most up-to-date public listing of human-caused quakes ever made. By bringing the data together in this way, they hope to highlight how diverse induced quakes can be and help society to understand and manage future risk.
The largest earthquake recorded in the database is the magnitude 7.9 temblor that hit Sichuan, China, in 2008. Some scientists suggested that the earthquake was linked to the filling of a nearby reservoir. Wilson says his team was initially startled to see quakes that large proposed as human-induced. But in retrospect, he said: "We probably shouldn't be surprised by any anthropogenic cause." All projects linked to earthquakes, whether blasting a mining tunnel, injecting wastewater or pumping groundwater, involve moving mass around on the Earth's surface in ways that can nudge already stressed faults.
With this rate, scientists warn to be ready for more human-induced quakes in the future.