After the volcanic destruction in 1931 the W foot of the mountain was harassed by heavy banjirs, which beat in pieces the bridges and covered fields with sand. The banjir problem of the Merapi was studied in detail by K.G.R. Schmidt, a separate detailed report about this is in preparation by him.
A good 20 km2 terrain, with 13 kampungs completely and 20 kampungs has partly destroyed by the big eruptions of December 18 and 19, 1930, causing 1369 men and a good 2100 big cattle killed and more than 1100 house lost.
A rain-triggered lahar occured in K.Boyong (Southern slope of Merapi volcano) on 19 February 1995. This lahar was the biggest in this channel since 22 November, 1994 Merapi eruption which left more than 2 million cubic meters of pyroclastic flow deposits as far as 6 km from the summit.
The EDM measurement at the summit area of Merapi volcano had been done periodically in 1988, 1990, 1991, and 1992. By using the data of trilateration, horizontal strain components were calculated to evaluate strain pattern changes with time. During the period of 1988 - 1990, seismic and eruptive activities were rather low. In the period of 1990 - 1991, HFA and HFB type earthquakes increased and…