After a sharp increase in seismic activity detected on September 29, 2016, Indonesian authorities have raised the alert level of Iya volcano on the island of Flores from 1 (normal) to 2 (watch). A 2 km (1.2 miles) exclusion zone around the crater was established. The last eruption of this volcano took place in 1969 and measured VEI 3. This is the first significant change in activity under Iya volcano since the eruption of 1969.
PVMBG first detected increased activity at 08:30 UTC (15:30 local time) on September 29. Within the next 18 hours, they recorded 8 relatively large tectonic earthquakes of magnitudes around 5 and 17 volcano-tectonic quakes. The normal for the month is 4 - 8 volcanic earthquakes and between 5 and 14 tectonic earthquakes.
This increased activity indicates that there is an increase in the pressure of magma to the surface.
With its peak about 637 m (2 089 feet) above sea level, Iya volcano is administratively located in Ende, East Nusa Tenggara Province.
Historically, Iya has erupted at least 8 times with VEI of around 2 to 3 (on a scale of 8). The biggest and the last eruption of this volcano occurred on January 27, 1969. It had volcanic explosivity index of 3.
Local people, fishermen, and tourists are not allowed to approach the crater within 2 km (1.24 miles) around the crater.
In the case of eruption, PVMBG warns, people who conduct activities on river valleys surrounding the volcano are expected to be vigilant, especially during the rainy season.
Gunung Iya is the southernmost of a group of three volcanoes comprising a small peninsula south of the city of Ende on central Flores Island. The cones to the north, Rooja and Pui, appear to be slightly older than Iya and have not shown historical activity, although Pui has a youthful profile (a reported 1671 eruption of Pui was considered to have originated from Iya volcano).
Iya, whose truncated southern side drops steeply to the sea, has had numerous moderate explosive eruptions during historical time.
Featured image: Iya volcano, 1985. Credit: VSI