Hi All. Most of us remember the Loma Prieta earthquake that rocked the San Francisco Bay area in 1989, killing 62 people and causing $6 billion in damage.

During that event, Stanford University electronics engineer and geophysicist Antony Fraser- Smith had a magnetometer set up seven miles from the epicenter of the 6.9-magnitude event. He was using the magnetometer to measure ultra-low-frequency (ULF) radio waves, a Navy-funded project aimed at studying the use of ULF waves for submarine communications.

Examining their data after the Loma Prieta quake, Fraser-Smith's team discovered that a huge spike in ULF levels occurred three hours before the quake. "This was the biggest signal we've ever seen," he says.

There is a little problem with this precursor. It could be the signal of an impending quake, but it doesn’t tell you when the quake will occur although the average seems to be around 3 hours before the quake. If you live in a city such as San Francisco there will be very precious little time to evacuate the city and surrounding area.

You could make the equipment more sensitive, but then you run the risk of detecting ULF that may not be related to a future quake. The other problem is that ULF is not fully understood. Most feel that it is caused by rock deformation. They also know that it doesn’t always occur just before a major quake. This may be because the ULF sensor hasn’t been located in the right place, or there may not be any at all. Take Care…Don in creepy town

• ULF