If you ever took a look at Li’l Volcanohead’s path around the world in the last two and a half years, you would think it is starting to look like a ball of twine. I try to be random in my adventurousness, and have crossed my own path often. But every once in a while I find myself back in a place I have already been because some places are worth visiting twice. But when I flew over this caldera and found myself overwhelmed by a feeling of deja volc, I was surprised to learn that I had in fact not been here before, despite setting foot on almost every other subaerial volcano in the vicinity of the infamous tri-plate junction, where the Azores rise from the Atlantic ocean as beautiful green volcanic islands like Corvo.
The Azores consist of nine volcanic islands and thirteen volcanoes. Some of the islands share a single island, but also (perhaps in the interest of preventing overcrowding.. 😉 ) two of the thirteen volcanoes are submarine. The entire island archipelago, which is around 560 km long from northwest to southeast, sits upon the Azores Platform, a submerged land form that rises to a broad but rugged plateau at an average 2,000 m below sea level. Eleven of the thirteen volcanoes are arranged right along the transform boundary between the Eurasian and African tectonic plates and considered rift zone volcanoes. However, the other two volcanoes lie across the Mid Atlantic Ridge on the North American plate, and are said to be intraplate or hotspot volcanoes. The Azores hotspot is popularly believed to be a small (and perhaps dying) hotspot that at present is centered beneath the island of Faial.
Geologically speaking, Corvo island is the easternmost piece of land belonging entirely to North America, but geographically speaking, it and the other Azores islands are an autonomous region of Portugal. The 17 km2 island has been settled by humans since the late 16th century, and in 2006 had a population of 468. There is one village on the island, Vila do Corvo, which includes a small airport. The island economy mostly involves dairy cattle and cheese production.The island itself was built atop a 1-1.5 million year old seamount. An ancestral volcano called Monte Gorde first emerged around 730,000 years ago and achieved a height of 1,000 m before collapsing in a Plinian eruption 430,000 years ago. The resulting caldera is around 2,000 m wide and 300 m deep. The floor of the caldera contains a few small cinder and spatter cones and several small lakes. There are several flank vents on the south of the volcano which have erupted lavas that expanded the island southward and upon which Vila do Corvo is built. The eastern slopes and parts of the caldera have been put to agricultural use, but the western side of the island is an almost vertical 700 m cliff. The highest point of the island is the southern rim of the caldera, called the Morro dos Homens.
These days, Corvo volcano appears to be quite asleep, his hotspot long since departed. Some parts of the volcano are protected as resource or habitat conservation areas, and since there is only sparse tourist traffic, the volcano is probably enjoying his retirement very much.Answers to Extra Credit questions
1:1 – sub-Plinian
1:2 – picrite, or picro-basalt
2:1 – Flores island
2:2 – vesicles.
3:1 Morro do Homens (although according to Wikipedia, Estreitinho is also an acceptable answer.)
3:2 – intraplate
Congratulations are in order once again for Aficientifico, who found me on day one for 5 points, as well as picking up 4 points for Extra Credit. Also welcome to the scoreboard karenj26, who picked up one point for Extra Credit. I hope to see you return this coming Monday around 23:00 NYC-time, when I once again try to outrun the Search Party and have a new adventure at a new volcano.