Unzen Volcano in which this observatory is installed is the active volcano that occupies most in the Shimabara peninsula. It is the composite volcano where many lava domes of amphibole andesite-dacite projected in the volcanic central part. Since the history started, although the eruption is seen in 1663,1792,and 1990,each eruption point is restricted to the highest peak of Mt.Fugen (altitude: 1359m). Among these, Furuyake lava flowed out in the eruption in 1663.The volcanic mudflow occurred from the old crater, and about 30 people died by it at the next year. Moreover, in the eruption in 1792,since Shinyake lava flows out, large collapse starts the last stage by Mt.Mayuyama which adjoins the east and tsunami was induced, it became the greatest volcanic disaster in our country which reaches no less than 15,000 dead people on the Ariake sea coast. Although it is uncertain, there are such natural disasters and trace generated also in 679. (the Chikushi big earthquake).From the career of such past, it is anxious about relapse of the large calamity in Unzen Volcano, and the research about large collapse of Mt.Mayuyama and enforcement of the observation of volcanic activity were demanded strongly previously. Moreover, since the hot spring of varieties is also sprung in the Shimabara peninsula, when studying the volcano phenomenon and the mechanism of earthquake generating, it was also the suitable place.
Those days of 1955,the Aso volcano research institution(1927) of Faculty of Science, Kyoto University which is the oldest institution in our country was installed in with resumption(1955) of the eruption of Sakurajima, Sakurajima Volcano Research Center, Disaster Prevention Research Institution(1960) was founded. Moreover, preparation for establishing the Kirishima Volcano Research Center (1963) was advanced at Earthquake Research Institution, the University of Tokyo by the eruption (1959) for the first time in 36 years of Mt.Kirishima. Those days as faculty, the opportunity that the research observation institution for volcanoes should have been furnished was increasing in connection with a related group having begun to be substantial. In response to support of the Nagasaki prefecture and Shimabara City, temporary institution “Shimabara Institution of Volcanology and Balneology” was started, and earthquake observation was started in the eastern foot of Mt.Mayuyama in March,1962. Furthermore, the prefectural possession building and the city possession site which were borrowed were purchased in 1967.One assistant was employed and researches of the large collapse of Mt.Mayu and hot spring were also started. From 1968 just behind it, swarm earthquakes became very remarkable in the whole Shimabara peninsula, shakes or big sounds accompanied it also, and great uneasiness was given to local residents. For the reason, preparation of a research observation attitude always in the Unzen volcano came to be requested strongly. The Shimabara observatory was founded in such situation by the background in April, 1971.While the geochemical research for the volcanic hot spring was promoted succeedingly at the beginning, the introduction to the observation of volcanic activity was tried. Although “the first volcanic-eruption predictions five year plan” was inaugurated in 1974,this observatory equipped the network for observation of earthquakes by three points and the equipment for observing volcanic-gases. Moreover, this observatory also participated in concentration synthesis observation of the main active volcanoes of the whole country which came to be carried out by this plan in annual, using geochemical observation of volcanic gases and hot spring. Those days, since all other volcanological observatories were carrying out only geophysical observation, this observation was very unique existence. By this concentration observation, observation of volcanic gases and hot spring was started also in Sakurajima, Mt.Aso, and Mt.Asama. This observation was continuously carried out until it made unavoidable the discontinuation by the eruption of Mt.Unzen in 1990.
On the other hand, the central area in Kyushu also including the Shimabara peninsula is the leading zone to which earthquakes occur frequently also in our country, and there has been a lot of damage by the shallow earthquake of inland. This zone is the large collapse zone, the Beppu-Shimabara graben that has developed from the Beppu bay ranging over the Shimabara peninsula. It is thought that these earthquake groups are exactly as a result of the expansion phenomenon of the graben, disuniting Kyushu in north and south. Although the earthquake caused by this graben is a very small scale earthquake and a middle scale earthquake (M<7), since it has generated in the shallow portion of directly under, although it is local, it is often accompanied by remarkable damage. Nevertheless, although the earthquake network was nationally equipped by the earthquake prediction plan of our country, since only the here region was in the country where research observation is not started, also socially, it was called in question. In order to cope with such situation, the seismology group was established by faculty of science, the Kyushu University in 1980. However, as the observation Institution, the established Shimabara Volcano Observatory will be expanded, it will result in the conversion to the present Shimabara Earthquake and Volcano Observatory in April,1984. Moreover, it participated in the planning of the earthquake prediction plan from 1984, and expansion and equipment of networks of seismic observation were aimed at for the central part and the northern part in Kyushu.
Now, while this observatory carries out regular earthquake observation by sixteen observing networks and nine networks of seismic observation of the Unzen Volcano area, it is carrying out data exchange of each observing points (which adjoins the observing points of Kyushu University) with Kagoshima University, the University of Tokyo, Kochi University, and the Meteorological Agency. Thereby, this observatory accomplished development to the regular observation preparedness of the earthquake in almost all the areas in Kyushu, observation area center in Kyushu. Moreover, in the Unzen Volcano, in addition to the establishment of an dip, total intensity, and observing points of global positioning system (GPS), the gravimeter, the surveying equipment were newly equipped for observation reinforcement of the eruption activity started for the first time 198 years much more fullness of the observation and research of volcanic phenomenon.