Listening Device Provides Landslide Early WarningA device that provides early warning of a landslide by monitoring vibrations in soil is being tested by UK researchers. The
device could save thousands of lives each year by warning when an area should be evacuated, the scientists say. Such natural disasters arc common in countries that experience
sudden, heavy rainfall, and can also be triggered by earthquakes and even water erosion.
Landslides start when a few particles of soil or rock within a slope start to move, but the early stages can be hard to spot. Following this initial movement, "slopes can
become unstable in a matter of hours or minutes," says Nell Dixon at Southborough University1, UK. He says a warning system that monitors this movement "might be enough to
evacuate a block of flats or clear a road, and save lives. "
The most common way to monitor a slope for signs of an imminent landslide is to watch for changes in its shape. Surveyors can do this by measuring aside directly, or sensors
sunk into boreholes or fixed above ground can be used to monitor the shape of a slope. Slopes can. however, change shape without triggering a landslide, so either method is
prone to causing false alarms. Now Dixon's team has developed a device that listens for the vibrations' caused when particles begin moving within a slope.
The device takes the form of a steel pipe dropped into a borehole in a slope. The borehole is filled in with gravel around the pipe to help transmit high-frequency
vibrations generated by particles within the slope. These vibrations pass up the tube and are picked up by a sensor on the surface. Software analyses the vibration signal to
determine whether a landslide may be imminent.
The device is currently being tested in a 6-metre-tall artificial clay embankment in Newcastle2, UK. Early results suggest it should provide fewer false positives than
existing systems. Once it has been carefully and thoroughly tested, the device could be used to create a complete early-warning system for dangerous Slopes.
" Locations with a significant risk of landslides could definitely benefit from a machine like this," says Adam Poulter, an expert at the British Red Cross. "As long as it
doesn't cost too much, " But, Poulter adds that an early-warning system may not be enough on its own. "You need to have the human communication," he says. "Making systems that
get warnings to those who need them can be difficult. "
41. What does "Such natural disasters" in the first paragraph refer to?
A Sudden, heavy rainfall.
B Earthquakes.
C Water erosion.
D Landslides.
42. Which of the following statements is true of landslides?
A The initial movement is hard to spot.
B They start with a movement of a few particles of soil or rock.
C They can be destructive in a matter of hours or minutes.
D All of the above.
43. Why do researchers develop a new device to monitor signs of landsides?
A Because the new device can measure the site directly.
B Because the new device can be sunk into boreholes
