Listening DeviceProvides Early Landslide（山崩；地滑；塌方）Warning

A device thatprovides early warning of a landslide by monitoring vibrations（振动）in soil is being tested

by UK researchers.The device couldsave thousands of lives each year by warning when an area should be

evacuated（疏散，撤走）,the scientists say. Suchnatural disasters are common in countries that experience

sudden , heavyrainfall（降雨，降雨量）, and canalso be triggered by earthquakes and even water

erosion（腐蚀，侵蚀）.

Landslides startwhen a few particles of soil or rock within a slope start to move,but the earlystages can

be hard tospot.Following this initial movement,"slopes can become unstable in amatter of hours or

minutes,"saysNell Dixon at Southborough University,UK. He says a warning system thatmonitors this

movement"mightbe enough to evacuate a block of flats or clear a road,and save lives".

The most common wayto monitor a slope for signs of an imminent（即将发生的）landslide is to watch

for changes in itsshape. Surveyors can do this by measuring aside directly , or sensors（传感器）sunk into

boreholes（钻孔，井眼）or fixed above ground can beused to monitor the shape of a slope. Slopes can,

however,change shapewithout triggering a landslide,so either method is prone to causing falsealarms.Now

Dixon's team has developed a device that listens for thevibrations caused when particles begin moving

within a slope.

The device takes theform of a steel pipe dropped into a borehole in a slope.The borehole is filledin

with gravel（砾，沙砾，砾石）around the pipe to helptransmit high-frequency vibrations generated by particles

within theslope.These vibrations pass up the tube and are picked up by a sensor on thesurface.Software

analyses thevibration signal to determine whether a landslide niay be imminent.

The device iscurrently being tested in a 6-metre-tall artificial clay embankment（堤岸）in Newcastle,

UK. Early results suggest it should providefewer false positives than existing systems.Once it has been

carefully andthoroughly tested,the device could be used to create a complete early-warningsystem for

dangerous slopes.

"Locations witha significant risk of landslides could definitely benefit from a machine likethis,"says

Adam Poulter,anexpert at the British Red Cross,"As long as it doesn't cost toomuch."But,Poulter adds

that anearly-warning system may not be enough on its own."You need to have thehuman communication,"

he says,"Makingsystems that get warnings to those who need them can be difficult."Which of thefollowing statements is true of landslides?

A.The initialmovement is hard to spot.

B.They start with amovement of a few particles of soil or rock.

C.They can bedestructive in a matter of hours or minutes.

D.All of the above.