Shield Volcano
Topographic Features
"Shield volcanoes, are built almost entirely of fluid lava flows. Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warrior's shield. They are built up slowly by the accretion of thousands of highly fluid lava flows called basalt lava that spread widely over great distances, and then cool as thin, gently dipping sheets. Lavas also commonly erupt from vents along fractures (rift zones) that develop on the flanks of the cone. Some of the largest volcanoes in the world are shield volcanoes. In northern California and Oregon, many shield volcanoes have diameters of 3 or 4 miles and heights of 1,500 to 2,000 feet. The Hawaiian Islands are composed of linear chains of these volcanoes including Kilauea and Mauna Loa on the island of Hawaii-- two of the world's most active volcanoes. The floor of the ocean is more than 15,000 feet deep at the bases of the islands. As Mauna Loa, the largest of the shield volcanoes (and also the world's largest active volcano), projects 13,677 feet above sea level, its top is over 28,000 feet above the deep ocean floor.
In some eruptions, basaltic lava pours out quietly from long fissures instead of central vents and floods the surrounding countryside with lava flow upon lava flow, forming broad plateaus. Lava plateaus of this type can be seen in Iceland, southeastern Washington, eastern Oregon, and southern Idaho. Along the Snake River in Idaho, and the Columbia River in Washington and Oregon, these lava flows are beautifully exposed and measure more than a mile in total thickness."[1]
Examples
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CSV| Geothermal Resource Area | Geothermal Region | Tectonic Setting | Host Rock Age | Host Rock Lithology | Mean Capacity | Mean Reservoir Temp |
|---|---|---|---|---|---|---|
| Akita Geothermal Field | Northeast Honshu Arc | Subduction Zone | Tertiary | Dacite | 88.3 MW 88,300 kW 88,300,000 W 88,300,000,000 mW 0.0883 GW 8.83e-5 TW | 548.15 K 275 °C 527 °F 986.67 °R |
| Gunun-Salak Geothermal Area | Sunda Volcanic Arc | Subduction Zone | 345 MW 345,000 kW 345,000,000 W 345,000,000,000 mW 0.345 GW 3.45e-4 TW | 548.15 K 275 °C 527 °F 986.67 °R | ||
| Iwate Geothermal Area | Northeast Honshu Arc | Subduction Zone | Miocene; Pre-Tertiary | Dacitic welded tuff; Marine Sediments Tuffs; Shales; Chert; Slate; Granodiorite | 103.5 MW 103,500 kW 103,500,000 W 103,500,000,000 mW 0.104 GW 1.035e-4 TW | 578.15 K 305 °C 581 °F 1,040.67 °R |
| Java - Darajat Geothermal Area | Sunda Volcanic Arc | Subduction Zone | Volcanics | 255 MW 255,000 kW 255,000,000 W 255,000,000,000 mW 0.255 GW 2.55e-4 TW | 518.15 K 245 °C 473 °F 932.67 °R | |
| Java - Dieng Geothermal Area | Sunda Volcanic Arc | Subduction Zone | Lavas | 60 MW 60,000 kW 60,000,000 W 60,000,000,000 mW 0.06 GW 6.0e-5 TW | 598.15 K 325 °C 617 °F 1,076.67 °R | |
| Java - Kamojang Geothermal Area | Sunda Volcanic Arc | Subduction Zone | 200 MW 200,000 kW 200,000,000 W 200,000,000,000 mW 0.2 GW 2.0e-4 TW | 518.15 K 245 °C 473 °F 932.67 °R | ||
| Java-Wayang Windu Geothermal Area | Sunda Volcanic Arc | Subduction Zone | 227 MW 227,000 kW 227,000,000 W 227,000,000,000 mW 0.227 GW 2.27e-4 TW | 558.15 K 285 °C 545 °F 1,004.67 °R | ||
| Kagoshima Geothermal Area | Ryuku Arc | Subduction Zone | Neogene to recent | Volcanic Rocks, Andesite | 0.1 MW 100 kW 100,000 W 100,000,000 mW 1.0e-4 GW 1.0e-7 TW | 512.15 K 239 °C 462.2 °F 921.87 °R |
| Kilauea East Rift Geothermal Area | Hawaii Geothermal Region | Hot Spot | Quaternary | Tholeiitic Basalt | 47 MW 47,000 kW 47,000,000 W 47,000,000,000 mW 0.047 GW 4.7e-5 TW | 575.15 K 302 °C 575.6 °F 1,035.27 °R |
| Mak-Ban / Laguna Geothermal Area | Philippine Island Arc | Subduction Zone | 457.75 MW 457,750 kW 457,750,000 W 457,750,000,000 mW 0.458 GW 4.5775e-4 TW | 618.15 K 345 °C 653 °F 1,112.67 °R | ||
| Mindanao Geothermal Area | Philippine Island Arc | Subduction Zone | 105 MW 105,000 kW 105,000,000 W 105,000,000,000 mW 0.105 GW 1.05e-4 TW | 533.15 K 260 °C 500 °F 959.67 °R | ||
| Mutnovskaya Geothermal Area | Kuril-Kamchatka Arc | Subduction Zone | Oligocene | 62 MW 62,000 kW 62,000,000 W 62,000,000,000 mW 0.062 GW 6.2e-5 TW | 507.15 K 234 °C 453.2 °F 912.87 °R | |
| South Negros Geothermal Area | Philippine Island Arc | Subduction Zone | 242 MW 242,000 kW 242,000,000 W 242,000,000,000 mW 0.242 GW 2.42e-4 TW | 573.15 K 300 °C 572 °F 1,031.67 °R | ||
| Tiwi / Albay Geothermal Area | Philippine Island Arc | Subduction Zone | Andesite | 330 MW 330,000 kW 330,000,000 W 330,000,000,000 mW 0.33 GW 3.3e-4 TW | 593.15 K 320 °C 608 °F 1,067.67 °R |
References
- ↑ 1.0 1.1 John Watson. Principal Types of Volcanoes [Internet]. 2011. U.S. Geological Survey. [updated 2011/01/03;cited 2013/12/24]. Available from: http://pubs.usgs.gov/gip/volc/types.html