How do scientists monitor the volcano?

Scientists of the Seismic Research Centre monitor volcanic activity at Kick-‘em=Jenny using a network of instruments installed on nearby islands. The monitoring system includes seismometers (to detect earthquakes), tide gauges (to detect water disturbances), hydrophones (to detect submarine explosions) and tiltmeters and GPS stations (to detect ground deformation). Various combinations of these instruments are installed at Sauteurs, the Sisters rocks, Isle de Ronde, Isle de Caille and Carriacou, and their signals are transmitted to a small base station located at Sauteurs in northern Grenada. From here, the signals are sent to Trinidad. The most important monitoring technique at an active volcano such as Kick-‘em-Jenny is seismic monitoring. Normally, magma (molten rock) is stored in a magma chamber deep beneath the volcano, but if it begins to move towards the surface it will crack rocks as it forces its way up and thus generate earthquakes. Such earthquakes are called “volcanic earthquakes”, and are usually small and shallow, so it is easy to identify them. When many volcanic earthquakes occur beneath a volcano, then scientists know that the volcano might erupt in the near future. This is what happened at Kick-’em-Jenny on Dec 4th 2001. Many small volcanic earthquakes occurred throughout the day, and so the Seismic Research Unit increased the alert level at the volcano. At about 7.15 pm there was indeed a small eruption.