Virtual Volcano Vacation #42 WINNER! – Suwanose-jima

A small vulcanian explosion on 29 December 2009 - Original image at Photovolcanica.com

A small vulcanian explosion on 29 December 2009 – Original image at Photovolcanica.com

Our reigning champion Leslie has made a triumphant return this week after combing the virtual Earth (with a nit comb, probably) to find me at Suwanose-jima volcano in the Tokara Islands in the south of Japan.

View onto an old cinder cone on the rift zone (Photo: Tom Pfeiffer) - Original image and caption at VolcanoDiscovery

View onto an old cinder cone on the rift zone (Photo: Tom Pfeiffer) – Original image and caption at VolcanoDiscovery

The Tokara Islands are a volcanic archipelago that owe their existence to the Philippine Plate, which is subducting beneath the Eurasian Plate and keeps Suwanose-jima and her neighbors (including the more famous Sakura-jima) well supplied with rising magma.

Suwanose-jima island is populated by less than 50 people..most likely most of whom belong to a Japanese counter-culture commune that established itself there in the sixties. The volcano herself is one of the most active in Japan, and has a history of chasing people off her island. One such eruption in 1813-14 produced a subplinian column of ash, deposited tephra all over the island, created two distinct andesitic lava flows down her west flank and ultimately caused her east flank to collapse and formed the Sakuchi Caldera which extends to the island’s east   The island’s settlements were abandoned and she had the island to herself for the next seventy years, which she appears to have spent being quiescent..except for one indulgent VEI 4 explosive eruption in 1877. Then in 1884-85 she welcomed the newly-returned humans to her island by sending a long lava flow toward the east coast.She has two summit craters, but most of her modern activity centers around the northeast O-take crater vent (sometimes called On-take or Ontake..not to be confused with Mount Ontake further north on Honshu).

A steam plume rises above On-take, the summit crater of Suwanose-jima volcano. The 8-km-long, spindle-shaped island of Suwanose-jima consists of a stratovolcano with two historically active summit craters. The dipping escarpment at the top of the photo is the NW wall of a large breached crater that extends to the sea on the east flank. The horseshoe-shaped crater was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, has been in a state of intermittent strombolian activity since 1949. Photo by Yukio Hayakawa, 1998 (Gunma University). Original caption and image at GVP

A steam plume rises above On-take, the summit crater of Suwanose-jima volcano. The 8-km-long, spindle-shaped island of Suwanose-jima consists of a stratovolcano with two historically active summit craters. The dipping escarpment at the top of the photo is the NW wall of a large breached crater that extends to the sea on the east flank. The horseshoe-shaped crater was formed by edifice collapse. Suwanose-jima, one of Japan’s most frequently active volcanoes, has been in a state of intermittent strombolian activity since 1949.
Photo by Yukio Hayakawa, 1998 (Gunma University). Original caption and image at GVP

She has remained active through the 20th and 21st centuries, including her most recent eruption, an ongoing affair that has lasted a little over eleven years.  But a deeper look at the layers of tephra on the south of the island reveals a >23,000 year old 15 m thick ignimbrite overlying a 3 m thick layer of rhyolite pumice, giving reason to believe this volcano has had quite a violent past.

But she is an artist in her own way, as this exposed cliff of more recent layers of ejecta demonstrates.

Colorful scoria and ash deposits in the NE cliff of the island (Photo: Tom Pfeiffer) - Original image and caption from VolcanoDiscovery

Colorful scoria and ash deposits in the NE cliff of the island (Photo: Tom Pfeiffer) – Original image and caption from VolcanoDiscovery

Be sure to come back here on Monday evenings (NY-time) every week for a new volcano and new adventure. Also, my blog-anniversary and 50th Virtual Volcano Vacation challenge will be coming up in late December..and I am thinking up something to make that one extra special. I will have more to say about that in weeks to come.

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