Today, the technology exists to detect earthquakes in the immediate future, so quickly, that an alert can reach some areas before strong shaking arrives. This can be done by detecting the energy through p-waves which rarely cause damage; these are detected through a huge network of extremely high quality motion sensors. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage. lahar-detection system http://volcanoes.usgs.gov/activity/methods/hydrologic/lahardetection.php
The automated detection system relies on a series of acoustic-flow monitor (AFM) stations installed downstream from a volcano. Each station consists of a seismometer that senses ground vibrations from an approaching and passing lahar and a microprocessor that analyses the signal. Every second, the microprocessor samples the amplitude of the vibration detected by the seismometer. Every half an hour a signal is sent to the base station and an emergency message is sent any time the vibrations exceed a programmed threshold for longer than 40 seconds.
Like a carpenter's level, an electronic tiltmeter uses a small container filled with a conducting fluid and a “bubble” to measure a change in slope. In particular the tilt on the earth’s surface before a volcanic event. Electrodes placed in the fluid and into the bubble determine the bubble's position--as the bubble moves, voltage output from the electrode changes in a way that correlates to the amount of tilt that caused the bubble to move. Tiltmeters measure the amount of tilt in microradians, which is the angle turned by raising one end of a beam one kilometer long the width of a dime (equivalent to 0.00006 degree!)
A Seismometer is an instrument used to detect and record earthquakes. Generally, it consists of a mass attached to a fixed base. During an earthquake, the base moves and the mass does not. The motion of the base with respect to the mass is commonly transformed into an electrical voltage. The electrical voltage is recorded on paper, magnetic tape, or another recording medium. This record is proportional to the motion of the seismometer mass relative to the earth, but it can be mathematically converted to a record of the absolute motion of the ground.
GPS Data http://earthquake.usgs.gov/monitoring/gps/ As part of the earthquake process, Earth's surface is being deformed as earthquake faults accumulate strain and slip or slowly creep over time. GPS is used to monitor this movement by measuring the precise position (within 5mm or less) of stations near active faults relative to each other.
There are large populations which choose to live in volcano and earthquake prone areas. Given that prediction of impending volcanic eruptions and earthquakes are currently unreliable, people cannot react to such events which can lead to devastating natural disasters. There for a reliable early warning would save many lives and reduce losses due to poor preparation for a disaster. Research and use of new technologies is expensive but the cost is small compared to the possible savings in lives, the provision of emergency services and loss of work, after a devastating event. The use of new technologies, such as modern microcomputers, and remote sensing technologies, offer great potential for reliable methods of prediction to be developed in the near future.
Earthquakes however are difficult or impossible to predict because of their extremely random behaviour. Efforts