The future danger of Mt. Kelut (Eastern Java — Indonesia)

The tunnel system of Hettinga Tromp proved that the Kelut dangers can be controlled to such an extend that no great lahars were formed during the eruption of 1951. This eruption, however, destroyed these tunnels. In 1954, a drainage tunnel system was built based on the seepage principle. But till now it has failed to drain the lake completely. The 23.5 million cb.m of water still stored up in its crater lake will form a potential danger during an eventual eruption.     

Recent changes in the Anak-Krakatau volcano

A two day visit to the Anak-Krakatau on March 15–16, 1963, revealed that dramatic changes have taken place recently in the Anak-Krakatau volcano. A new topographic survey for the major changes in the top area was completed; two maps and several sections showing the growth and changes in the Anak-Krakatau are presented. The former moonshaped crater lake (1960) has completely disappeared and instead lava flows cover the crater floor between the inner cone and the outer ring wall. Lava streams flowed over the lowest south western crater rim and spread fan-wise into the sea. This activity with the production of lava flows must have taken place between 1960 and the beginning of 1963.     

Preliminary report on the 1963 eruption of Mt.Agung in Bali (Indonesia)

Mt. Agung in Bali which has been dormant for about hundred and twenty years showed increased activity on February 18 this year culminating with a paroxysmal eruption early in the morning on March 17; the second paroxysmal eruption occurred on May 16. The activity started with minor explosions in the main crater with the production of pyroclastics followed by the effusion of lavas which flowed over the lowest northern crater rim and the formation of nuées ardentes d’explosion which came down into the northwestern sector of the volcano. Successive nuées ardentes d’explosion which accompanied the paroxysmal cruption on March 17 and on May 16, came down along the southern, southeastern and northern slopes, devastating many villages. The first cycle of activity killed about 1700 people of which 1500 died from the nuées ardentes. Cold lahars, caused by heavy rainfall immediately after the eruption destroyed villages and constructions on the southern slope and killed about 200 more people. The nuées ardentes from the second paroxysmal eruption killed also about 200 more people who were all caught in the « Closed Zone ». A map showing the devastated area is presented.