The information below comes from the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as the Center for Volcanology and Geological Hazard Mitigation, or CVGHM), the Darwin Volcanic Ash Advisor Center (VAAC), and MODIS thermal sensors aboard satellites.
Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera.
A Darwin VAAC ash advisory stated that an ash explosion on 7 June at 0020 UTC generated a plume that rose 4 km in altitude and drifted 13 km SW a day later.
Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were not observed between 19 November 2016 and 6 June 2017.
In response to these news reports Emmanuel Ramos of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) sent a reply on 17 September.
PHIVOLCS staff had initially heard that there were some 12 alleged families who fled the mountain and sought shelter in the lowlands.