Over time, we as humans, have become better at predicting occurrences. We have learned to predict the path and intensity of a typhoon to a very accurate extent. Aside from storms, humans have also learned to predict volcanic eruptions much more accurately. Over the course of time, humans have accumulated knowledge to predict upcoming volcanic eruptions with more certainty than before. The eruption of Mt. Pinatubo in 1991 is an example of the expansion and evolution of human prediction skills.

In the spring of 1991, Mt. Pinatubo in the Philippines began to rumble and quake until there were some explosions from the mountain. From the explosions, there were three craters, and from each of these craters, steam was rising out of the mountain. Worried about a possible eruption, the Philippine government placed a seismometer on the mountain. About 400 earthquakes were recorded by the seismometer and this brought anxiety to the Philippine government and the US as there were 2 air force bases within the vicinity of the mountain. At that time, three possible predictions were made. The best case scenario was a harmless incident; the mountain was merely letting out steam. The second best case scenario was shifts in the tectonic plate. Although there would be some damage to structures in the immediate area near the mountain, the damage would be minimal and limited to that area. The worst case scenario was that magma was rising from the volcano as this could lead to an eruption.


To make proper and accurate predictions regarding the state of the volcano, US and Philippine volcanologists studied and observed the volcano intensely. Three seismic meters were placed in areas on the volcano to measure the ground activity. Correlation spectrometers were placed near volcanic vents to measure the amount of S02  that leaves the volcano. Numerous reconnaissance flights were made to determine the shape of the volcano, the craters, and the surrounding landscape to determine how it was going to erupt. The memory of Mount St. Helens was freshly ingrained in the minds of the volcanologists who did not expect the lateral eruption of the mountain thus resulting in more deaths than expected. Trees buried by past pyroclastic flows were carbon dated to estimate the frequency of eruptions. The trees indicated that Mt. Pinatubo erupted two to three times over the past thousand years. Usually, the less often a volcano erupts, the more violent the eruption when the volcano erupts.

It was only until the S02 levels increased exponentially after declining slightly and the formation of a dome structure where the magma was escaping when the evacuation protocol was enacted. 48 hours after Clark air base was evacuated, the mountain unleashed ash 100,000 feet into the air. The gas and particles emitted by the volcano were large enough to contain lightning within its own weather system. People from Manila could feel ash landing on their palms; and yet, deaths were minimized because there was advanced warning due to enhanced predicting methods. As technology became more sophisticated; enough to pick up more minute indicators of eruptions such as small earthquakes in the ground or the amount of gas escaping the mountain; coupled with greater experience from past lessons such as Mount St. Helens has allowed more accurate and precise predictions to be made.