セントへレンズ。
彼我の差は大きい。
観測システムへの予算投入の差だけではないように思う。
> ************************
> Mount St. Helens update
> ************************
> U.S. Geological Survey, Vancouver, Washington
> University of Washington, Pacific Northwest Seismograph Network, Seattle,
> Washington
>
> Mount St. Helens Volcano Advisory (Alert Level Two)
> September 29, 2004 10:40A.M., PDT
>
> Over night, seismic activity at Mount St. Helens has accelerated significantly,
> which increases our level of concern that current unrest could culminate in an
> eruption. We are increasing the alert level to the second of three levels,
> which is similar to Color Code Orange of the alert system used by the Alaska
> Volcano Observatory and analogous totheNational Weather Service’s hazardwatch.
> Earthquakes are occurring at about four per minute. The largest events are
> approaching Magnitude 2.5 and they are becoming more frequent. All are still at
> shallow levels in and below the lava dome that grew in the crater between 1980
> and 1986. This suggests that the ongoing intense earthquake activity has
> weakened the dome, increasing the likelihood ofexplosions or perhaps the
> extrusion of lava from the dome.
>
> The cause and outcome of the accelerating unrest is uncertain. Explosions from
> the lava dome could occur suddenly and without further warning. During such
> explosions the dome and crater floor are at greatest risk from ballistic
> projectiles, but the rim of the crater and flanks of the volcano could also be
> at risk. Explosions would also be expected to produce ash clouds that rise
> several thousand feet above the crater rim and drift downwind. During today,
> wind forecasts from the National Weather Service, combined with eruption
> models, show that ash clouds will move in a southeasterly direction and could
> dust areas tens of miles or more from the volcano with ash. Landslides and
> debris flows from the crater that are large enough to reach the Pumice Plain
> are also possible. If the current unrest is being driven by a small slug of
> magma at shallow depth, extrusion of lava could also occur. At present there is
> no evidence that new gas-rich magma has ascended to shallow levels and could
> generate a large sustained eruption. But we are being especially vigilant to
> become aware of such evidence should it appear.
>
> We continue to monitor the situation closely and will issue additional updates
> as warranted, whether activity escalates or returns to background levels.
>
> Daily updates of earthquake data and other information can be found on the
> WORLD WIDE WEB at URL:
>
> http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity
> (CVO Menu - Monthly Summaries and Updates)
>
> and
>
> http://www.pnsn.org/HELENS/welcome.html
> (University of Washington - Earthquake Update)
>
>
> --------
> see also:
> http://story.news.yahoo.com/news?
> tmpl=story&cid=578&ncid=578&e=8&u=/nm/20040929/ts_nm/environment_volcano_dc
>
> "Mount St. Helens on Higher Eruption Alert"
>
> excerpt:
>
> SEATTLE (Reuters) - Mount St. Helens could erupt within days, government
> scientists said on Wednesday, raising the alert after movement in the volcano's
> lava crust was detected following a week of small earthquakes.
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![[http://www5.kannet.ne.jp/~tonesabo/asama2.jpg]](http://www5.kannet.ne.jp/~tonesabo/asama2.jpg){kind=link}