Nisyros, Greece

By ExploreNow Editor, on April 3rd, 2012%

Nisyros Volcano

Volcano Type:      Stratovolcano
Volcano Status:    Historical
Last Known Eruption:     1888
Summit Elevation:     698 m     2,290 feet
Latitude:     36.586°N     36°35’8″N
Longitude:     27.160°E     27°9’35″E

The easternmost volcano of the Aegean arc forms the 9-km-wide island of Nisyros, which is truncated by a 3-4 km wide caldera. The island was constructed during the past 150,000 years, with three cone-building stages including explosive and effusive andesitic eruptions and effusive and extrusive dacitic and rhyolitic activity. The age of the caldera is variously considered to be <24,000 years before present (BP) (Keller et al., 1990) and >44,000 years BP (Limburg and Varekamp, 1991). Five large post-caldera lava domes completely fill the western part of the caldera. The NE-most (Boriatiko) and SW-most (Karaviotis) lava domes and flows are significantly younger than the other domes. A sixth post-caldera dome, outside the SW caldera rim, produced lava flows that reached the coast. Historical phreatic eruptions occurred from craters within the caldera between 1422 and 1888. Intense hydrothermal activity continues in the form of many fumaroles on the caldera floor and hot springs along the coast.

Nisyros Volcano

Nisyros Volcano

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Originally posted 2010-08-20 05:00:13.

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Santorini (Thera), Greece

By ExploreNow Editor, on March 6th, 2012%

Volcano Type:      Shield volcanoes
Volcano Status:    Historical
Last Known Eruption:     1950
Summit Elevation:     367 m     1,204 feet
Latitude:     36.404°N     36°24’13″N
Longitude:     25.396°E     25°23’47″E

Renowned Santorini (Thera), with its steep-walled caldera rim draped by whitewashed villages overlooking an active volcanic island in the center of a caldera bay, is one of the scenic highlights of the Aegean. The circular island group is composed of overlapping shield volcanoes cut by at least four partially overlapping calderas. The oldest southern caldera was formed about 180,000 years before present (BP), followed by the Skaros caldera about 70,000 years BP, and then the Cape Riva caldera about 21,000 years BP. The youngest caldera formed about 3600 years BP during the Late-Bronze-Age Minoan eruption that forced abandonment of the thriving Aegean Sea island. Post-Minoan eruptions beginning in 197 BC constructed a series of lava domes and flows that form two islands near the center of the caldera. A submarine eruption took place in 1650 AD outside the caldera NE of Thera. The latest eruption at Santorini produced a small lava dome and flow in 1950, accompanied by explosive activity.

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Originally posted 2010-08-17 04:25:00.

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