Fault-monitoring technique could help to predict earthquakes
A team of US scientists has developed a technique for monitoring the strength of geographical faults, paving the way for better prediction of earthquakes.
Because many seismic faults are buried deep below the Earth’s surface, it’s difficult to gather information about their current state, in particular their strength. Earthquakes occur when a fault fails, either because of a buildup of stress or a weakening of the fault.
Paul Silver and colleagues examined data collected over a 20-year period using highly sensitive seismometers to detect tiny changes in earthquake waves as they travelled through the San Andreas Fault zone near Parkfield, California. In a paper in Nature, they described how these data revealed the presence of fluid-filled fractures within the fault zone. These areas were observed to shift from time to time, the shifts corresponding with a weakening and increased frequency of small earthquakes. These changes, in turn, indicated a weakening of the fault.
‘Movement of the fluid in these fractures lubricates the fault zone and thereby weakens the fault,’ said Fenglin Niu, one of the paper’s authors. Intriguingly, these weakening events corresponded to major earthquakes elsewhere on the planet, suggesting that large seismic events can trigger later events in distant locations.
December 2009
Because many seismic faults are buried deep below the Earth’s surface, it’s difficult to gather information about their current state, in particular their strength. Earthquakes occur when a fault fails, either because of a buildup of stress or a weakening of the fault.
Paul Silver and colleagues examined data collected over a 20-year period using highly sensitive seismometers to detect tiny changes in earthquake waves as they travelled through the San Andreas Fault zone near Parkfield, California. In a paper in Nature, they described how these data revealed the presence of fluid-filled fractures within the fault zone. These areas were observed to shift from time to time, the shifts corresponding with a weakening and increased frequency of small earthquakes. These changes, in turn, indicated a weakening of the fault.
‘Movement of the fluid in these fractures lubricates the fault zone and thereby weakens the fault,’ said Fenglin Niu, one of the paper’s authors. Intriguingly, these weakening events corresponded to major earthquakes elsewhere on the planet, suggesting that large seismic events can trigger later events in distant locations.
December 2009
|
FIND OUT WHAT WE'RE TALKING ABOUT ON TWITTER:
| |
 |
