科技英语新闻:Scientists look at drilling sea floor to study "silent" quakes

WELLINGTON, July 29 (Xinhua) -- Scientists from around the world will gather on the east coast of New Zealand next week to discuss proposals to study "silent" earthquakes by drilling into the seabed.

Silent quakes, also known as slow slip events, occur on the boundaries of the earth's tectonic plates, where one plate dives under another in areas known as subduction zones, and are slower than normal quakes, taking weeks or months to occur rather than seconds, and are rarely felt on the surface.

About 70 scientists from 10 countries will convene in the city of Gisborne, which lies near the site of a major fault line and where scientists first identified silent earthquakes in 2002.

Slow-slip events were first discovered with the advent of new measurement technologies on the west coast of Canada about 15 years ago and have since been recorded at about a dozen locations around the world, including four sites around New Zealand, said a spokesperson for New Zealand's Institute of Geological and Nuclear Sciences (GNS Science).

About eight slow-slip episodes have occurred under Gisborne since 2002 at roughly two-year intervals.

Scientists have proposed numerous theories to explain the phenomenon, but testing the theories is difficult as silent quakes happen many kilometers below ground.

"The best way to understand the true cause of slow-slip events is to drill into and sample the area on the plate boundary fault where they are known to occur, and monitor a whole range of physical and chemical properties at the plate interface," said Laura Wallace, of GNS Science.