Earthquakes Detectable From Space by GPS

Iphtashu Fitz writes "Research sponsored mainly by the European Space Agency has demonstrated that earthquakes generate acoustic signals, almost like a huge loudspeaker, that can be detected from space. According to an ABC News Science/Technology article, geophysicist Juliette Artru came up with the concept while working on her doctorate degree. By monitoring an array of GPS receivers located throughout California she was able to determine that a massive 7.9 earthquake in Alaska last year resulted in the constillation of GPS satellites generating a mesaurable amount of interference. According to Artru, "A displacement of one millimeter on the ground can cause a displacement of 100 meters in the ionosphere," so a tiny pressure wave created by an earthquake can undergo huge amplification by the time it reaches the ionosphere. The resulting shockwave causes a tiny but very distinct pattern of interference in the GPS signals broadcast by the satellites."

Comments

Further info:

[Saint Aardvark]

Juliette Artru's homepage has further information on her research. Particularly interesting is the application of this technique to tsunamis: "This observation opens exciting perspectives for the study of tsunamis, not only for early warning purposes but also to characterize their propagation in the ocean."

A paper of hers from 2001 presents information on the Mount Pinatubo eruption. An abstract of the paper discussed in the ABC story is also available.

eek...

[M-G]

from the article: ...the displacement sends out an acoustic signal, or radio wave, that moves up through the atmosphere.

Uh, is it an acoustic wave, or a radio wave? There is a difference.

From the post: resulted in the constillation of GPS satellites generating a mesaurable amount of interference.

The constellation of GPS satellites did not generate any interference. Rather the effect of the wave on the ionosphere caused interference in the RF signals from the GPS sats.