While the experts debate if these types of petrol/gas extraction methods cause the earthquakes, in just about every part of the US where these methods have been used earthquakes follow, including regions that haven’t had quakes in modern history. My impression of building standards in Spain is that things are build to last a long time, but they are not built for earthquakes.
Government halts activity at gas storage plant as tremors worsen
More than 20 earthquakes were detected during Wednesday night alone
“The Industry Ministry and the Valencia regional government announced on Thursday that work on an offshore gas-storage plant, located off Spain’s Mediterranean coast, would be halted indefinitely until the cause of a series of earthquakes that have been detected in coastal towns in the area is established.
Industry, Energy and Tourism Minister José Manuel Soria announced on Thursday that there “appears to be” a “direct relation” between the injection of gas into the Castor offshore storage plant and the tremors. The minister did, however, add that there was still no “scientific evidence” to prove a cause and effect.”