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Comment: 22:04 - 22:22 (00:18)
Source: Annenberg/CPB Resources - Earth Revealed - 9. Earthquakes
Keywords: Parkfield, earthquake, groundwater, "San Andreas Fault", "creep meter", stress, fault
Our transcription: Before the next Parkfield Earthquake, scientists hope to see an acceleration of the slip that occurs on the San Andreas Fault between earthquakes.
If that acceleration takes place at the surface, it can be detected directly by a creep meter.
But geologists must use other techniques to detect deep movement along the fault that does not appear as slip at the surface.
As stress accumulates in the Earth, groundwater will respond by rising or falling.
This can be measured in water wells that have been installed by members of the Parkfield research team.
A sudden drop in water level, for example, is sometimes observed as the ground swells and cracks in the days preceding an earthquake.
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