CVGHM reported that on 3 June the water in Kelimutu’s Crater II (Tiwu Nua Muri Kooh Tai Crater) turned from blue to a light brown color, “smoke” rose 50 m above the crater, “rustling water sounds” were heard near the wall of Crater I (Tiwu Ata Polo), and a sharp sulfur odor was noted. That evening a weak sulfur odor was reported in Pemo (3 km). Plants within 2 km S and SE appeared to have wilted.

Based on seismicity from 20 May-2 June and visual observations on 3 June, CVGHM raised the Alert Level to 2 (on a scale of 1-4), and warned the public not to approach the craters within a radius of 2 km and to avoid river valleys.

Geological Summary. Kelimutu is a small, but well-known, Indonesian compound volcano in central Flores Island with three summit crater lakes of varying colors. The western lake, Tiwi Ata Mbupu (Lake of Old People) is commonly blue. Tiwu Nua Muri Kooh Tai (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched, or Enchanted Lake), which share a common crater wall, are commonly colored green and red, respectively, although lake colors periodically vary. Active upwelling, probably fed by subaqueous fumaroles, occurs at the two eastern lakes. The scenic lakes are a popular tourist destination and have been the source of minor phreatic eruptions in historical time. The summit is elongated 2 km in a WNW-ESE direction; the older cones of Kelido (3 km N) and Kelibara (2 km S).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)