Termasuk lanjutan pemintaan Kep. U.G.A Jogyakarta tgl 11 Mei 1954 No. 249/60/UGA/M/54 dan dengan surat perintah Kep. Djawatan Pertambangan Tjb. Jogjakarta tgl 17 Juli 1954 No. 116/Um, penulis mengerjakan Trianguleren di Pos U.G.A Krindjing.
Sehubungan dengan surat tugas No. 125/Um. tgl 28/8-1954 dari Kepala Cabang Djawatan Pertambangan Yogyakarta, beserta Sdr. Merkum maka kami mulai menyelenggarakan bunyi pasal 2 (Mengadakan peilingen ke bagian - bagian dari puncak), dari surat No. 249/60/UGA/M/54 tertanggal 11 Mei 1954 oleh Kepala U.G.A Yogyakarta.
Laporan ini membahas Gunung - Gunung berapi yang berada di daerah Jawa Timur, yaitu: (1) Kawah Idjen; (2) Gunung Raung; (3) Gunung Semeru; dan (4) Gunung Bromo.
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.
After the December eruption 1930, the laducourses of Merapi Volcano, Central Java previously showed no water circulation, expect at big rainfall, which caused shorthliving banjirs.
The ladumasses were deeper cut in the course of the mouths and it appears always clearer, that they were built of a heterogen, lightbrown colored sand mass, where in-between irregularly scattered, the stones occurred as individuals or as bouldertrails.
Almost all authors are the opinion, that the well - known wedusgembel, which caused death and destruction on the western slope of the Merapi, originated from the hot lava avalanches (glowing avalanches), which rolled down along the slides, whereas 'shout-out' wedusgmbel have not taken place.