Perhaps the most challenging thing about earthquakes is the great uncertainty around where and when they are likely to strike, which makes taking action that may save lives challenging.
Earthquakes bring about redistribution of mass and this generates observable changes of the Earth’s gravitational field, measurable using specialized instruments. High accuracy gravity measurements may provide a useful tool to help with managing the risk by identifying which faults (断层) are under stress and most likely to be active. By monitoring the progression of fault movements, it’s possible to get a medium-term outlook on which areas are most likely to be affected when the next earthquake happens.
Current earthquake warning systems are based on networks which detect the early arrival “P” seismic (地震的) waves prior to the arrival of the more destructive waves, but are unable to respond before the ground movements have already started, greatly limiting how advanced the warning can be.
While a warning caused by a gravity signal might only give a few additional seconds, such a warning can provide extra time to allow the public to take preventative action.
However, making measurements of gravity with sufficient accuracy, long-term stability and data sampling rate to achieve these signals is of course challenging. Detection of small signals for early warning systems is greatly limited by the background seismic noise which affects the sensor readings. Obtaining measurements which are stable over long periods of time and consistent between different sensors is difficult too.
The Quantum Technology Hub for Sensors and Timing led by the University of Birmingham is developing sensors which meet these challenges by employing the quantum (量子) behaviour of cold atoms to measure gravity accurately. As well as the cold atom sensors being extremely sensitive to small changes in the gravitational field, the identical (完全相同的) nature of atoms makes them ideal test masses which give consistent results.
Furthermore, by measuring two separated atom clouds at the same time, common background seismic noise can be controlled, which helps to overcome the limitations of seismic noise and allows fast and accurate measurements.
【小题1】What is mainly talked about in paragraph 2?| A．How earthquakes are formed. | B．How people can better predict earthquakes. |
| C．What is used to monitor earthquakes. | D．What is the way to identify active faults. |
| A．The number of sensors. | B．The temperature of atoms. |
| C．The background seismic noise. | D．The strength of seismic waves. |
| A．They have the same nature. | B．They are tiny. |
| C．They are sensitive to temperature. | D．They can remove the seismic noise. |
| A．To display the uncertainty of earthquakes. |
| B．To show the challenges in detecting earthquakes. |
| C．To discuss the accuracy of earthquake warning systems. |
| D．To introduce a technology to improve earthquake detection. |
