 Mount Iraya last erupted in 1454, and the Philippine Institute of Volcanology and Seismology (PHIVOLCS) considers it as one of the active volcanoes in the Philippines.In 1998, volcanologists recorded seismic swarms which led them to form a monitoring network on Batan Island for several months.After the swarms of tremors had diminished, the temporary stations in Barangay San Joaquin in Basco, Batanes and another near the crater, were pulled out.