The Jailolo volcanic complex forms a peninsula west of Jailolo Bay on the western coast of Halmahera Island. The stratovolcano at the center of the complex has youthful lava flows on its E flank. Small calderas are located to the W and SW. The westernmost caldera, Idamdehe, truncates an older twin volcano of Jailolo. Hot springs occur along the NW coast of the caldera. Kailupa cone forms a small volcanic island off the southern coast of the peninsula. Hot mudflows were reported shortly prior to 1883, but no eruptions are known during historical time.