美国阿拉斯加州大锡特金火山为全美唯一橙色警戒火山：熔岩缓流持续，希沙尔丁火山11月2日降至正常与绿色
美国阿拉斯加州阿留申群岛中部的大锡特金火山（Great Sitkin）熔岩仍在缓慢流入山顶火山口。阿拉斯加火山观测站（AVO）在周六上午9时50分（阿拉斯加标准时间）发布的最新每日更新中说：「熔岩很可能仍在大锡特金火山的山顶火山口内缓慢喷发。过去一天在火山附近探测到几次小地震。云层遮挡了其他卫星与网络摄像头的视野。」
该火山维持火山警戒级别「观察」（WATCH）与航空颜色代码橙色（ORANGE）。美国地质调查局（USGS）周日早间的隆起火山名单显示，大锡特金是全美唯一处于橙色级别的火山；夏威夷的基拉韦厄与北马里亚纳群岛的阿伊海底火山列为「咨询」（ADVISORY）与黄色。
AVO 周五中午12时10分发布的每周更新提供了更多细节：卫星图像显示，过去一周活跃熔岩穹丘略有生长，穹丘南翼正缓慢向南移动；整周云层遮挡了全部可见光图像，地震活动保持低水平，偶有小规模火山地震与熔岩流生长引发的小型落石信号。本轮喷发始于2021年7月，此后熔岩流已填满山顶火山口的大部分并推进至下方谷地；自2021年5月的一次爆炸事件以来，大锡特金未再发生爆炸。
大锡特金山顶海拔5,709英尺，最近的社区阿达克（Adak）位于火山西南偏西约26英里处。AVO 表示，该站主要依靠本地地震与次声传感器、卫星数据、网络摄像头以及区域次声与闪电网络远程监测这座偏远火山。
阿拉斯加其他火山方面，AVO 已于11月2日将乌尼马克岛上的希沙尔丁火山（Shishaldin）降至「正常」（NORMAL）与绿色，称其在一年多的隆起活动后动荡正缓慢减弱，目前预计不会喷发。大锡特金由此成为阿拉斯加唯一高于「正常」级别的火山。
Alaska's Great Sitkin Is the Only U.S. Volcano at Orange Alert: Lava Keeps Oozing Into the Summit Crater as Shishaldin Is Lowered to Normal and Green on November 2
Lava is still oozing slowly into the summit crater of Great Sitkin Volcano in Alaska's central Aleutian Islands, the Alaska Volcano Observatory (AVO) said, keeping the remote volcano as the only one in the United States at the second-highest alert status.
In its most recent daily update, issued at 9:50 a.m. AKST on Saturday, the observatory said: "Lava likely continues to erupt slowly within the summit crater of Great Sitkin Volcano. A few small earthquakes were detected at the volcano over the last day. Clouds obscured other satellite and webcam views of the volcano." The volcano remained at Volcano Alert Level WATCH and Aviation Color Code ORANGE, and AVO reported no major change in activity since Saturday as of early Sunday.
The U.S. Geological Survey's list of elevated volcanoes early Sunday showed Great Sitkin as the only U.S. volcano at ORANGE; Kilauea in Hawaii and Ahyi Seamount in the Northern Mariana Islands were listed at ADVISORY and YELLOW.
AVO's weekly update, released at 12:10 p.m. AKST on Friday, said minor growth of the active lava dome within the summit crater was observed in satellite imagery over the past week, with the south flank of the dome moving slowly southward. Seismic activity remained low, with occasional small volcanic earthquakes and signals from minor rockfalls caused by the growing lava flow. The current eruption began in July 2021; since then, lava flows have filled most of the summit crater and advanced into valleys below, and there have been no explosions at Great Sitkin since an event in May 2021.
Great Sitkin's summit rises to 5,709 feet; the community of Adak is about 26 miles west-southwest of the volcano. AVO monitors the remote volcano using local seismic and infrasound sensors, satellite data and webcams, along with regional infrasound and lightning networks.
Elsewhere in Alaska, AVO lowered Shishaldin Volcano on Unimak Island to NORMAL and GREEN on November 2, 2026, following more than a year of elevated activity, saying unrest is slowly declining and an eruption is not expected at this time. Great Sitkin is now the only Alaska volcano above NORMAL.
来源：阿拉斯加火山观测站
发布：GSM·美国（发布链接）
图片来源：图：大锡特金火山岛。NASA，公共领域，经 Wikimedia Commons。 / Photo: Great Sitkin Island, Alaska. By NASA, public domain, via Wikimedia Commons.
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