Satellite image from 5th June 2017 shows a white plume originating from Saunders Island drifting south. The plume also appears in an image from 9th June drifting west-southwest and again on 10th June drifting west. The likelihood is that it's more likely to be a gas or vapour emission. No thermal anomaly was detected at around that time.
Emission from Saunders Island on the 5th June 2017. SOURCE: Suomi NPP/VIIRS/NASA.