Megata

Megata is a volcanic group on the Oga Peninsula in northwestern Honshu, Japan. It consists of three basaltic-to-dacitic maars at the edge of the peninsula. These maars measuring between and across are filled with water, forming freshwater lakes. Ichinomegata is the widest and oldest of the three. These features date to around the Pleistocene although pottery discovered between layers of tephra has been dated to 4,000 years before present. An older and larger maar is located offshore on the western coast of the peninsula, known as Toga (Togowan), it formed 450,000 years ago. The western wall of Toga maar is breached, forming a bay.