Earthquakes are a natural disaster—except when they're man-made. The oil and gas industry has forcefully used the technique known as hydraulic fracturing (水力压裂法) to destroy sub-surface rock and liberate the oil and gas hiding there. But the process results in large amounts of chemical-filled waste water. Horizontal drilling (水平钻孔) for oil can also produce large amount of natural, unwanted salt water. The industry deals with this waste water by pumping it into deep wells.
On Monday, the US Geological Survey published for the first time an earthquake disaster map covering both natural and “induced” quakes. The map and a report show that parts of the central United States now face a ground-shaking disaster equal to the famously unstable terrain (不稳定地形) of California.
Some 7 million people live in places easily attacked by these man-made quakes, the USGS said The list of places at highest risk of man-made earthquakes includes Oklahoma, Kansas, Texas, Arkansas, Colorado, New Mexico, Ohio and Alabama. Most of these earthquakes are relatively small, in the range of magnitude (震级) 3, but some have been more powerful, including a magnitude 5.6 earthquake in 2011 in Oklahoma that was connected to waste water filling.
Scientists said they do not know if there is an upper limit on the magnitude of man-made earthquakes; this is an area of active research. Oklahoma has had prehistoric earthquakes as powerful as magnitude 7.
It's not immediately clear whether this new research will change industry practices, or even whether it will surprise anyone in the areas of newly supposed danger. In Oklahoma, for example, the natural rate of earthquakes is only one or two a year, but there have been hundreds since hydraulic fracturing and horizontal drilling, with the waste water filling, became common in the last ten years.
【小题1】What kind of human activities can cause earthquakes?| A．The man-made produced waste water in the factories. |
| B．The process of digging deep wells in those poor areas. |
| C．The advanced techniques used to deal with waste water. |
| D．The oil or gas industry's work connected with the earth. |
| A．Man-made. | B．Reduced. |
| C．Newly-built. | D．Controlled. |
| A．It's been said as small as magnitude 3. |
| B．It has been said as high as magnitude 7. |
| C．It's being studied without a final conclusion. |
| D．It has risen by an average of magnitude 5. 6. |
| A．Natural Earthquakes in America Are Disappearing Now |
| B．7 Million Americans at Risk of Man-Made Earthquakes |
| C．Time for Oil and Gas Industry Change Their Working Practice |
| D．More Often Earthquakes as Powerful as Magnitude 7 in America |
