Mechanical Monitoring Methods (Long Term, Decades-Years)
Most earthquake forecasting has focused on studying mechanical indicators in the recent past
- Stress build up (GPS and INSAR monitoring of plate motion)
- Strain Monitoring (Strain meters)
- Seismicity rates (chaos theory, quake gap theory)
Electromagnetic Monitoring Methods (Short Term, Weeks-Days)
More recently, the International community has started to monitor Electromagneticsignals
The basis of this theory is that rocks near the hypocenter of the impending quake are stressed to their elastic limit and begin to crack --without actually displacing (rupturing) yet. This cracking process releases a flood of charged particles (some researchers say electrons, some say positive charge carriers called p-holes, and some simply say ionic water migrates through the cracks). These moving charges form huge underground currents (10^6 Amps estimated in the 1999 Chi-Chi, Taiwan quake) which disturb the Earth's normal magnetic field. These disturbances can be detected at ultra-low frequencies (ULF) due to the signal's ability to penetrate kilometers of solid rock only at low frequencies (electromagnetic skin effect). Some lab experiments have also shown that p-holes can migrate to the surface, drop their charges, and emit IR radiation in discreet frequencies bands (NASA-Freund) that have been detected by satellite IR instruments (NASA-Ouzounov). There are other electromagnetic effects (see below).
