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Aviation safety: It comes as a surprise to many to learn that the north Pacific air routes are very busy. There are two main reasons for this. The first is the great-circle routes from North America to northeastern Asia (e.g. Tokyo and Hong Kong) which cross the north Pacific. The second is that most aircraft moving freight between Europe and northeastern Asia refuel in Anchorage, making Anchorage the number one dollar-value freight airport in the United States. This map illustrates these spatial relations -- click on it for a larger version. In all there are about 10,000 people per day, and nearly 60,000 flights per year which traverse the north Pacific air routes. And (this is where AVO comes in) those air routes are directly above the volcanoes of the Aleutian Islands and Alaska Peninsula (and directly downwind of the volcanoes of easternmost Russian and the Kurile Islands). Over 40 of Alaska's 80+ volcanoes are active, and at least 25 have produced major eruptions this century. In fact, the Alaska Peninsula hosted Earth's largest eruption this century. These volcanoes also are apt to erupt explosively, sending ash clouds directly up into the path of the aircraft. And ingestion of ash by aircraft engines, particularly those of the large aircraft used in international traffic (747's, L1011's, DC10's), is dangerous for many reasons. Mechanical damage and abrasion are caused by the ash. Also, the temperatures that the turbines operate at are about the melting point of volcanic glass (which is a major component of ash) -- so the ash can melt and seal over fuel nozzles and temperature sensors. All these combined forms of damage can cause -- and have caused -- large jet engines to stop in mid-air.
Adding to the danger is the fact that the Aleutians and
Alaska Peninsula are sparsely populated and have prolonged
periods of legendarily severe weather, so we can't rely on human
observers for timely eruption reports. Real-time seismic networks
send data directly to laboratories so that volcanoes can be
monitored around the clock (either by people or automatic alarms),
providing the type of information necessary to substantially
increase aircraft safety.
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