Why are subduction zones curved?

One of the most prominent features when looking on the large-scale topography of Earth are subduction zones. Since I have often wondered why they usually are arc-shaped I decided to delve a bit into the topic and share my findings in this post. It is mainly from a perspective of a geometrical model proposed in  “Why…

Onekotan volcano complex

The island of Onekotan lies to the south-west of Kamchatka, near the northern end of the Kuril island arc. The uninhabited island (excepting several Russian border guards), c45km x 7-15km across, contains two, at-present quiescent, active volcanoes, with Mt Krenitsyn in the south, the highest point at 1324m and Nemo Peak – 1019m – in the…