Kelimutu volcano (Flores Island, Indonesia) - Smithsonian / USGS Weekly Volcanic Activity Report for 10 July-16 July 2013 (New Activity / Unrest)

CVGHM reported that on 6, 10, and 12 June, and during 14 June-9 July, the color of the water in Kelimutu's Crater II (Tiwu Nua Muri Kooh Tai Crater) was bluish white. Diffuse white plumes rose as high as 50 m above the lake's surface and in some areas the water appeared or sounded like it was boiling. A sulfur odor was also reported.
The water in Crater I (Tiwu Ata Polo) was light green and churned, and the water in Crater III (Tiwu Ata Mbupu) was mossy green.

During 22-29 June sulfur dioxide concentrations from Crater II were occasionally detected at 2.8 ppm, when the wind blew the gas towards the sensor. CVGHM noted that plumes rising from the lakes became lower and barely visible during 3 June-9 July, and that the “rustling sound” of water from near the dividing wall of craters I and II gradually faded away. Based on visual observations, seismicity, and gas emissions, CVGHM lowered the Alert Level to 1 (on a scale of 1-4) on 12 July.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
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From: Global Volcanism Program, 2013. Report on Kelimutu. In: Mayberry, G (ed.), Weekly Volcanic Activity Report 10 July-16 July 2013. Smithsonian Institution and US Geological Survey.