Halmahera island
belongs to the North Moluccas province (Maluku Utara), Indonesia. This K-shaped island is located in the eastern part of the Moluccas Sea, the only active arc-arc collision complex on the Earth. The western arm of the island forms a volcanic arc generated by the former subduction of the Moluccas Sea plate underneath Halmahera. The region is characterized by intense seismic activity at crustal and intermediate depth, and along the subducting plate. At crustal level, seismicity in along the two eastern arms of  Halmahera show a strike-slip faulting style

In November 2015 an intense and energetic seismic activity started around Jailolo volcano in West Halmahera. The seismic sequence lasted intermittently until February 2016. Hundreds of events were felt by the population, several buildings were destroyed and damaged by the shaking. The largest shocks of the sequence were located by global seismicity networks (Geofon and GCMT) and identified as normal-faulting. The temporal evolution of the seismicity appears swarm-like rather than a simple mainshock-aftershock sequence.

In summer 2016 we instrumented the area with a dense seismic network composed of 29 short period and 6 broad-band seismometers, 6 GPS and 1 gas emission sensor. The aim of the instrument deployment is to understand the seismo-tectonics of the area and the relation between seismicity and volcanic activity at Jailolo volcano and the possible cause of the 2015-2016 swarm.