The studies and science of volcanoes is called "volcanology," and it originated with the accurate description of the eruption of Vesuvius in 79 A.D. The first documents of volcanology contained two letters from Pliny to the Roman historian Tacitus. In Pliny's letter, he described the death of his uncle who was killed in the eruption. However, it was not until the 19th century that serious scientific investigation into volcanoes flourished. In 1847, an observatory was established near Vesuvius. Before the first decade of the 20th century, the study of volcanoes was generally undertaken after the eruption had begun or ceased. The modern volcano monitoring is relatively new. Volcano monitoring basically is the keeping of a detailed journal of visible and invisible changes of a volcano and its surroundings. Between eruptions, importance visible changes include marked increase of decrease of steaming from vents; emergence of new steaming areas; development of new ground crack's unusual withering of plant life, etc. During the eruptive activity, scientists record the course of the eruption in details, make temperature measurements of lava, measure the flow rate of ash ejection and lava flows and carry out necessary observations and measurements.
Volcano monitoring also involves the recording and analysis of vocanic phenomena that are not visible to the human eye. Some common methods used to study invisible volcano-related phenomena are based on the measure of changes in the shape of the volcano, the precise determination of the location and magnitude of earthquakes and measurement of changes in the gas composition of the volcano.
A strikingly successful example of volcano research was the 1978 publication by two scientists Dwight Crandell and Donal Mullineaux. They concluded that Mount St. Helens was most likely to reawaken to eruption. Their prediction came true when Mount St. Helens came back to life in1980. Just as I said,volcanoes both bother and help mankind. Conducting your research on volcanology can be very helpful to human beings and trust me,it is fun. If you are interested to know more about volcanoes, you may read the booklist on the handout.Anyway,what I would like to concluded this lecture our improved understanding of volcanoes provides important clues to the Earth's past, present and its future.