Hi zusammen,
wiederum bei mir eingelangt:
AUGUSTINE SW Alaska, USA 59.3630N, 153.430W; summit elev. 1,252 m; All
times are local (= UTC 9 hours)
Explosive activity began at Augustine on 11 January. The day before, AVO
increased the Concern Color Code from Yellow to Orange when seismicity
began to increase at the volcano
<http://www.avo.alaska.edu/color_codes.php>. On 11 January at 0444
seismic signals began to be recorded that were interpreted as being
associated with explosions at Augustines summit. The Concern Color Code
was increased to Red, the highest level. Another explosion occurred at
0513, and satellite imagery confirmed that an ash plume was produced
that rose to ~9.1 km (30,000 ft) a.s.l. and drifted N and E. An ashfall
advisory was issued by the National Weather Service. Seismicity
decreased after the explosions. During a flight over the volcano,
scientists saw volcanic mudflows on the E, S, and W sides of the
volcano. Minor rock and snow avalanche deposits were visible high on the
SW part of the edifice. According to news articles, several flights were
canceled or diverted due to ash in air space.
On 12 January, the Concern Color Code was reduced to Orange. On 13
January, seismicity began to increase. An eruption on the 13th from
about 0355 to 0439 produced an ash plume to 10.4 km (34,000 ft) a.s.l.
On the 13th, the volcano entered a period of repetitive and explosive
eruptions, with explosions occurring at 0444, 0847, 1122, and 1640. Each
event produced ash plumes, mudflows, and pyroclastic flows. The ash
plumes produced from these eruptions rose higher than 9.1 km (30,000 ft)
a.s.l. Ash drifted ESE and a small amount of ash fell in communities of
the SW Kenai Peninsula. Explosions on the 13th at 1858 and on the 14th
at 0014 were similar in size and duration as the previous four. In
response to these eruptions, the National Weather Service issued an
ashfall advisory for the western Kenai Peninsula S of Ninilchik. No
explosions were recorded later on the 14th. The level of seismic
activity declined after an explosion on 14 January at 0016, so the
Concern Color Code was reduced to Orange on 15 January at 0945.
Observations on 16 January confirmed that pyroclastic deposits were
widespread on the volcanos flanks, as seen in web camera images. Also,
a small lava dome appeared to have extruded at the summit.
AVO reported on the 16th that the level of seismic activity at the
volcano remained above background. It is likely, but not certain, that
further explosive activity will occur. Explosive events similar to those
of 13 and 14 January could occur with little or no warning.
A strong seismic signal on 17 January marked the onset of an explosive
eruption. AVO changed the level of concern color code from ORANGE to RED.
Background. Augustine volcano, rising above Kamishak Bay in the southern
Cook Inlet about 290 km SW of Anchorage, is the most active volcano of
the eastern Aleutian arc. It consists of a complex of overlapping summit
lava domes surrounded by an apron of volcaniclastic debris that descends
to the sea on all sides. Few lava flows are exposed; the flanks consist
mainly of debris-avalanche and pyroclastic-flow deposits formed by
repeated collapse and regrowth of the volcano's summit. The latest
episode of edifice collapse occurred during Augustine's largest
historical eruption in 1883; subsequent dome growth has restored the
volcano to a height comparable to that prior to 1883. The oldest dated
volcanic rocks on Augustine are more than 40,000 years old. At least 11
large debris avalanches have reached the sea during the past 1800-2000
years, and five major pumiceous tephras have been erupted during this
interval. Historical eruptions have typically consisted of explosive
activity with emplacement of pumiceous pyroclastic-flow deposits
followed by lava dome extrusion with associated block-and-ash flows.
Sources: Alaska Volcano Observatory
http://www.avo.alaska.edu/activity/avoreport.php?view=update, Anchorage
Volcanic Ash Advisory Center
http://www.ssd.noaa.gov/VAAC/OTH/AK/messages.html, Los Angeles Times
http://www.latimes.com/news/nationworld/nation/la-na-briefs12.2jan12,0,3705867.story?coll=la-headlines-nation
Augustine Information from the Global Volcanism Program
http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-01-Link Nr. 2 + Nr. 4 funktionieren bei mir nicht, hoffentlich habt ihr mehr Glück!
Viele Grüße,
Angie
Thema: Vulkanausbruch in Alaska (Gelesen 4064 mal)