Report on Lawu (Indonesia) — May 1979
Scientific Event Alert Network Bulletin, vol. 4, no. 5 (May 1979)
Managing Editor: David Squires.
Lawu (Indonesia) Earthquake swarm during late 1978
Please cite this report as:
Global Volcanism Program, 1979. Report on Lawu (Indonesia) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 4:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197905-263260.
7.625°S, 111.192°E; summit elev. 3265 m
All times are local (unless otherwise noted)
The Indonesian newspaper Kompas reported that the first earthquakes of a swarm in the vicinity of the Lawu volcanic complex were felt on 10 December 1978. Area residents reported 14 felt shocks in December, five in January, two in February, six in March, and eight in April. The earthquakes were usually preceded by thunder-like rumbling from the direction of Lawu.
Seismicity became more frequent in late April and early May. At least four felt events occurred on 26 April, including a 10-second earthquake at 1900 that damaged a temple and a transmitting station. On 4 May a landslide in Lawu's Candradimuka Crater (in the S part of the complex) was followed by emission of a thick vapor cloud that was accompanied by a sulfur odor. Between the evening of 4 May and 0700 the next morning, nine events were felt. A total of 27 felt shocks occurred on 5 May, 37 on the 6th, and 35 on the 8th. A series of five earthquakes lasting 4-6 seconds each took place at about 1230 on 9 May. During a 12-hour period 14-15 May, there were more than 1,000 recorded events, more than 50 of which were felt. A VSI team is investigating the seismicity.
Further Reference. Tjia, H.D., and Hamidi, S., 1981, An earthquake swarm around Lawu volcano in Java: Berita Geologi, v. 13, p. 108-111.
Geologic Background. The massive compound stratovolcano Lawu contains an older, deeply eroded volcano on the north separated by a crescentic rift valley from the younger Lawu volcano of Holocene age (van Bemmelen, 1949b). Crater lakes and pyroclastic cones are found at the eastern side of the rift. The younger Lawu volcano contains eroded crater rims; its latest activity, including construction of a lava dome, occurred at the south end. A fumarolic area is located on the south flank at 2,550 m. The only reported historical eruption took place in 1885, when rumblings and light ashfall were reported. A major eruption reported from Lawu in 1752 was from neighboring Kelut volcano.
Information Contacts: Kompas, Jakarta.