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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…

Diamond Head. Image by ProveIt (Wikipedia, CC-BY-SA).

The Volcanic Landmarks of Oahu, Hawaii – Part 1, Diamond Head

Diamond Head is probably the most iconic landmark of Oahu.  You see it everywhere – from the beach, from your hotel room, on post cards, on travel brochures, in movies and television shows.  It is known to Hawaiians as Lēʻahi, most likely from lae’browridge promontory’ plus ʻahi ‘tuna’ because the shape of the ridgeline resembles the shape of a tuna´s dorsal…

Shiveluch_AquaModis_20140611

Activity update on Shiveluch volcano

  The volcanic ash advisory center (VAAC) Tokyo issued a warning this morning for ash hazard up to FL270 (8.2 km) extending south-west which by now has dissipated. KVERT has the volcano on orange alert and estimated the height of the ash plume to 13120-16400 ft (4-5 km) above sea level. The plume was barely visible on todays Aqua/Modis…