|(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)|
|(3) Volcano:||Semisopochnoi (VNUM #311060)|
|(4) Current Color Code:||YELLOW|
|(5) Previous Color Code:||UNASSIGNED|
|(6) Source:||Alaska Volcano Observatory|
|(7) Notice Number:||2015/A2|
|(8) Volcano Location:||N 51 deg 55 min E 179 deg 35 min|
|(10) Summit Elevation:||2625 ft (800 m)|
|(11) Volcanic Activity Summary:||Earthquake activity at Semisopochnoi that began in January continues, and has increased in intensity over the past few days. In addition, we have detected brief periods of seismic tremor, which can indicate movement of magma or magmatic gases. Thus we are increasing the aviation color code to YELLOW and the volcano alert level to ADVISORY.
AVO has not observed any other signs of volcanic activity in remote sensing or other data.
|(12) Volcanic cloud height:||Unknown|
|(13) Other volcanic cloud information:||Unknown|
|(14) Remarks:||Remote Semisopochnoi volcano occupies the largest young volcanic island in the western Aleutians. The volcano is dominated by a 7-km (5-mile) diameter caldera that contains a small lake and a number of post-caldera cones and craters. The age of the caldera is not known with certainty but is likely early Holocene. The last known eruption of Semisopochnoi occurred in 1987, probably from Sugarloaf Peak on the south coast of the island, but details are lacking. Another prominent, young post-caldera landform is Mount Cerberus, a three-peaked cone cluster in the southwest part of the caldera. The island is uninhabited and part of the Alaska Maritime National Wildlife Refuge. It is located 65 km (40 mi) northeast of Amchitka Island and 200 km (130 mi) west of Adak.|
|(15) Contacts:||John Power, Scientist-in-Charge, USGS
email@example.com (907) 786-7497
Jeff Freymueller, Coordinating Scientist, UAFGI
firstname.lastname@example.org (907) 322-4085
|(16) Next Notice:||A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at
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