| Penulis/Author |
Prof. Dr. Ir. Sugeng Sapto Surjono, S.T., M.T., IPU., ASEAN.Eng. (1) ; Dr.Ing. Ir. Donatus Hendra Amijaya, S.T., M.T., IPM. (2) |
| Abstrak/Abstract |
The recent October-November 2010 eruption of Merapi Volcano in Central Java, Indonesia has expelled around 1.5 to 2 million cubic meters of volcanic material. Heavy rain which occurs at the volcano has triggered frequent laharic flows which significantly bring volcanic material to the surrounding area. Characterized by its enourmous energy, this laharic flow is a serious threat for people who live within the surrounding of Merapi Volcano, especially nearby the rivers.
The area along some rivers in Magelang Regency of Central Java Province and Sleman Regency as well as Yogyakarta City of Yogyakarta Provinces, are the most affected areas by the geohazard caused by this sedimentary process. From November 2010 to January 2011, several laharic floods have struck those areas. Dams built to prevent the laharic floods were damaged. In Yogyakarta, thousands of inhabitants were evacuated several times to avoid casualties when the laharic floods came. Silting of the rivers occurs because of sediment deposition associated with these events.
The most severe impact took place in Magelang Regency. Jumoyo area, which is located about 15 km westward of Merapi Volcano was buried by laharic deposits. The laharic flow produced a new river path which split this area. Around 90 houses were damaged and 5000 people become refugees. The main road connecting Yogyakarta and Magelang was heavily damaged.
Extensive volcaniclastic sediment deposited on the peak and slopes of the volcano, a step slope, the deflection of the river path and the narrowing of the channel are the main causes of the large laharic flood. Attempts to prevent the negative impacts of the laharic flows in the future are needed, in particularly by widening and normalization of the rivers. |
