「糧船灣超級火山」區仕美資料整理

(綜合報道) (星島日報報道) 本港或可申請世界自然遺產！政府專家確認本港東南部首次發現一座曾於一億四千萬年前爆發的古代超級死火山，命名為「糧船灣超級火山」，超級火山直徑約二十公里，其獨特地貌演變，有助科學家了解歐亞板塊和菲律賓板塊的移動過程，而整個超級火山遺址有資格申請作世界自然遺產。

土木工程拓展署早前進行地質調查時，在本港東南部發現了一座古代超級死火山，是首次在本港以至中國東南部發現古代超級火山。署方指該死火山於一億四千萬年前最後一次爆發，命名為「糧船灣超級火山」，火山岩由糧船灣伸延至果洲群島，覆蓋西貢東部地質公園，其噴出的火山灰冷卻後形成著名的六角柱岩，而火山較深層部分則為花崗岩，由淺至深從西貢伸展至九龍及香港島。署方已就有關發現撰寫文章，並於今年一月在美國地球物理期刊《Geochemistry, Geophysics, Geosystems》中發表。

噴發火山灰形成六角柱岩

香港地貌岩石保育協會主席吳振揚指，本港早年申請成為世界地質公園時，已知西貢一帶有一座超級破火山口，現時政府確認火山位置，進一步證實當年申請理據。他估計，該超級破火山口直徑達廿公里，其由深層噴發的六角柱岩呈灰白色，屬酸性，與台灣澎湖和南韓濟洲等地由溶岩冷卻而成的六角柱岩不同。

吳振揚指該火山的獨特地貌特性，有助科學家解決現時歐亞板塊和菲律賓板塊的移動過程中的一些疑題，因此他認為整個超級火山遺址有資格申請做世界自然遺產，其極高的科研價值有助科學家了解地球演變過程。但他指，若政府打算申遣，有需要將現時世界地質公園範圍由陸地擴展一倍至海面，以保護整個火山遺址。

中大地理系教授伍世良指所謂超級火山，是以火山的噴發量來計算，其噴發量可達一千立方公里，以去年五月冰島格里姆火山爆發為例，當時火山灰令歐洲航空幾乎癱煥，但以火山爆發指數評估，糧船灣超級火山逾億年前的爆發威力，比於冰島火山強一萬倍。他指上一次超級火山爆發，為約七萬年前，位於印尼。

糧船灣發現古代超級火山

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本港西貢暗藏古代超級火山 1.4億年前曾爆發

大公網8月28日訊 香港首次發現古代超級火山！政府昨日宣布，在糧船灣的死火山經地質調查後證實屬于古代超級火山，單是由噴發的岩漿形成的火山岩，已由糧船灣延伸至果洲群島，而火山的深層部分也由西貢向九龍與香港島伸展。該火山最後一次爆發是一億四千萬年前。

1.4億年前曾爆發

土木工程拓展署昨日表示，位于香港東南部的「糧船灣超級火山」是首個在香港以至中國東南部發現的古代超級火山。火山的上部分為火山岩，由糧船灣伸延至果洲群島，覆西貢東部地質公園內大片土地。火山的較深層部分為花崗岩，由淺至深從西貢向九龍與香港島伸展。有關文章已于今年一月在美國地球物理期刊《Geochemistry, Geophysics, Geosystems》中發表。不過這座超級火山是死火山，最後一次爆發是一億四千萬年前，約中期侏羅紀至早期白堊紀。今日西貢東郊野公園糧船灣景區沿岸一帶布滿排列整齊、近乎垂直及高聳的六角柱火山岩柱，是超級火山噴出的火山灰經冷卻凝固後，形成的奇觀。

美國有最巨型火山 而現時世界最巨型的超級火山休眠于美國黃石國家公園地下，這座沉睡了六十萬年的火山在過去的二百一十萬年中，只爆發過三次，現時高度每年上升三--，顯示底下的岩漿已在不斷積聚。有專家曾預測，如果黃石火山爆發，四處飄散的火山灰有十--厚，並籠罩一千英里的範圍，並隨著有毒氣體的擴散，美國三分之二地區無法居住。當局會于星期四，在果洲群島對開海面舉行簡報會，介紹這次的發現。

Hong Kong sits on an ancient super volcano - but don't panic as the last eruption took place 140 million years ago. Situated in the southeastern part of the territory, the "High Island Super volcano" is the first of its kind discovered in the SAR as well as in southeastern China, according to the Civil Engineering and Development Department. The department will hold a media briefing on Thursday off the Ninepin Islands on the discovery. "This important finding is the result of geological surveying in Hong Kong carried out by the department," it said. A paper on the discovery was published in a US geophysical journal, Geochemistry, Geophysics, Geosystems, in January. "The upper part of this extinct volcano is represented by the volcanic rock covering a large area within the geopark in eastern Sai Kung," the department said. "It extends from High Island to the Ninepin Islands. "The cooled and solidified ash from the super volcano eruptions formed spectacular columns. "Progressively deeper parts of the super volcano, represented by granite, extend from Sai Kung toward Kowloon and Hong Kong Island." An expert said citizens need not worry about the super volcano erupting in their lifetime because it is already extinct. According to the Hong Kong Geopark website: "Rocks of the Ninepins date back to the age of dinosaurs - about 140 million years ago. It is believed that this group of islands were created by a major volcanic eruption which produced about 70 cubic kilometers of volcanic ash." In 1980, Mount St Helens in Washington state spewed out "only two cubic km of ash when it exploded while the catastrophic Krakatoa eruption in Indonesia in 1883 produced 12 cubic km of volcanic substances." Meanwhile, CNN will broadcast in its World's Untold Stories on Friday that one of the world's largest super volcanoes - which sits squarely in Yellowstone Park, and lying just eight kilometers beneath the Earth's surface "could wipe out" the United States. "It's a sleeping giant that's been at rest for more than 600,000 years, but its eruption is a potential catastrophic event that could kill millions," CNN said on its website. Super volcano is the popular term for large volcanoes that usually have a large caldera and can potentially produce devastation on an enormous, sometimes continental, scale. Such eruptions would be able to cause severe cooling of global temperatures for many years afterwards because of the huge volumes of sulfur and ash erupted. They can be the most dangerous type of volcano. Examples include Yellowstone Caldera in Yellowstone National Park, Lake Taupo in New Zealand and Lake Toba in Sumatra, Indonesia. Super volcanoes are hard to identify centuries later, given the enormous areas they cover. Large igneous provinces are also considered super volcanoes because of the vast amount of basalt lava erupted.