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Anticipating Earthquakes
dnahelix writes "Science @ NASA reports 'High above Earth where seismic waves never reach, satellites may be able to detect earthquakes--before they strike.'"
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The nice moire pattern in the photo showing changes in elevation was from after the quake. It does a nice job of showing how the stress along the fault was released at this point during a quake, but isn't directly a lot of help in predicting anything. However, one would assume that if you looked at similar photos along a known fault for long enough, there would be areas that did not show any colorfull moire patterns, surrounded by lots of color (indicating movement in the fault). Pretty cool, but I think most of the major faults already have this information from ground measurements.
The "60% chance of earthquakes in the next two days" portion of the prediction seems to rely on some piezo electric effect detected via magnetometers and thermal imaging. This has been speculated about for at least a couple of decades now, but I guess the signal to noise ratio is pretty bad since they haven't declared success yet. Maybe QuakeSat, mentioned at the end of the article, will provide enough comprehensive data to make some useful predictions. Predicting 12 out of the last 3 earthquakes isn't going to win you any friends!
A good number of volcanoes - such as those on Hawaii, are fitted with tiltmeters and laser-ranging reflectors.
As magma moves up towards the surface, some volcanoes start to 'inflate', bulging outwards. By measuring changes in tilt, and the geometry of the mountain, vulcanologists can get some warning of the changes under the mountain.
They usually combine this with seismic evidence (that moving magma creates swarms of tiny 'quakes), changes in gas production and the like to try and predict eruptions.
However, volcanoes are just as unpredictable. The USGS made a series of predictions about the Long Valley Caldera in Eastern California. It is an ENORMOUS crater which is underlain by an active magma chamber. The last volcanic activity in the region was about 400 years ago, and it is likely to continue into the future. Slap bang in the middle of Long Valley is the Mammoth Mountain ski resort, built around a dormant volcano.
In the early 1980s, the area around Mammoth Mountain began to bulge, molten rock was being forced upwards, there were swarms of 'quakes, trees began dying as CO2 bubbled up from underground. The USGS cautiously announced that they expected Mammoth Mountain to become active in the near future.
It didn't. The area remains highly active, but doomsday was put off for now.
BTW. if you ever get a chance to go to Mammoth Mountain, Long Valley and the Inyo Craters, do take it - the landscape is simply awe-inspiring.
Another example is Pozzuoli, which lies West of Naples in an area known as the Phlaegrean Fields. This is another colossal caldera with an active magma chamber. The last eruption was in 1538 when a new mountain (called Monte Nuovo somewhat unoriginally) was formed, the crater of Solfatara is still somewhat active, disgorging water and sulphurous fumes.
Pozzuoli is in the the middle of the Fields, a nice seaside town with some Roman ruins. However, during the 1970s, the area began to be shaken by hundreds of 'quakes a day. Even more worryingly, the area began to bulge upwards, sometimes by a centimetre a day! The Italian government ordered the evacuation of the entire city for several years, fearing another massive eruption. Eventually, the bulge subsided, the 'quakes faded and the people went back. But millions had been spent and enormous social dislocation caused.
It's quiet there at the moment, so everyone is looking East, over Naples to Vesuvius, which has been suspiciously quiet for far too long now.
Best wishes,
Mike.