Historical eruptions of Merapi Volcano, Central Java, Indonesia, 1768-1998

Information on Merapi eruptive activity is scattered and much is remotely l ocated. A concise and well-documented summary of this activity has been lon g needed to assist researchers and hazard-mitigation efforts, and the aim o f this paper is to synthesize information fi om the mid-1700s to the presen t. A descriptive chronology is given, with an abbreviated chronology in a t able that summarizes events by year, assigns preliminary Volcanic Explosivi ty Index (VEI) ratings and Hartmann classifications, and provides key refer ences. The history of volcano monitoring is also outlined. The study reveals that a major difference in eruption style exists between the twentieth and nineteenth centuries, although the periodicity between la rger events seems about the same. During the twentieth century, activity ha s comprised mainly the effusive growth of viscous lava domes and lava tongu es, with occasional gravitational collapses of parts of oversteepened domes to produce the nuees ardentes-commonly defined as "Merapi-type". In the 18 00s, however, explosive eruptions of relatively large size occurred (to VEl 4), and some associated "fountain-collapse'' nuees ardentes were larger an d farther reaching than any produced in the twentieth century. These events may also be regarded as typical eruptions for Merapi. The nineteenth centu ry activity is consistent with the long-term pattern of one relatively larg e event every one or two centuries, based on the long-term eruptive record deduced by others from volcanic stratigraphy. It is uncertain whether or no t a "recurrence-time'' model continues to apply to Merapi, but if so, Merap i could soon be due for another large event and its occurrence with only mo dest (or inadequately appreciated) precursors could lead to a disaster unpr ecedented in Merapi's history because the area around the volcano is now mu ch more densely populated. (C) 2000 Elsevier Science B.V. All rights reserv ed.