Mount Rainier Active Cascade Volcano (1994) / Chapter Skim
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4 Volcano Monitoring
4 Volcano Monitoring
Pages 62-75
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From page 62... ...
Ideally, these baseline data would comprise long, continuous series of observations collected at regular intervals during periods when no anomalous activity is occurring. These data series are needed to establish background or average values of behavior that would allow anomalous activity, which would rise above these background values, to be clearly identified.
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From page 63... ...
Seismic monitoring can also be used to detect the movement of glaciers on the volcanic edifice or movement of the edifice itself, which could signal impending glacier outburst floods, rockfalis, or slope failures. Since 1962, one seismometer has operated on Mount Rainier as part of a worldwide seismic station network (WWSSN station LON at Longmire, Washington)
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From page 64... ...
64 MOUNT RAINIER: ACTIVE CASCADE VOLCANo FIGURE 4. ~ Current seismic stations (circles)
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From page 65... ...
With the present array of seismometers, it is difficult to distinguish between surface seismic events caused by glacier movements on the edifice and shallow earthquakes beneath Mount Rainier (Weaver, 1976; Malone and others, 19911. This distinction is important, because shallow earthquakes might reflect the movement of magma to shallow levels in Me volcano and could signal an impending eruption.
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From page 66... ...
Monitoring of Ground Deformation Two common precursors of volcanic eruptions are uplift and lateral distension of the ground surface caused by upward movement of magma beneath and into the volcano. Such tumescence may involve a portion of the volcano, the entire volcano, or a broad region around it.
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From page 67... ...
Geological Survey, Mt. Rainier National Park, Wash., 1971, 1:50,000
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From page 68... ...
Good geodetic control of Mount Rainier could be obtained through real-time continuous GPS monitoring or frequent GPS surveys of the existing geodetic stations in the region and by the establishment of additional stations at higher elevations on the edifice. Frequent measurements of many points are needed to distinguish between changes in elevation due to magma movement and changes due to the seasonal accumulation and melting of snow on the edifice.
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From page 69... ...
This plume will probably contain gases such as sulfur dioxide and hydrogen sulfide, which are usually detectable by odor, as well as carbon dioxide, halogens, and other species. The remote measurement of such plume gases would be invaluable for determining the presence of shallow magma bodies that could feed volcanic eruptions.
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From page 70... ...
A short-term, nonseasonal change in snowpack or ice volume might signal increased Herman activity that could produce catastrophic outburst floods, debris flows, or, possibly, eruption. Several techniques could be usefully employed to monitor changes in snow or ice cover on the volcanic edifice: .
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From page 71... ...
MEMO ONTO ~ ~ it: !
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From page 72... ...
These hot spots define the margin of the main summit crater. Continued thermal infrared imagery of this area and of selected areas on the slopes of the volcanic edifice would provide the baseline information necessary for revealing a significant change in the pattern of heat flow related to a change in He pathways of warm water Trough the voIcano.
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From page 73... ...
Consequently, it is essential to monitor Me edifice for floods and debris flows after they have formed and are moving downsIope. Several hours generally pass between the initiation of a major lahar from Mount Rainier and runout of the lahar onto the lower slopes and floodplains surrounding tile volcano (Scott and others, 19921.
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From page 74... ...
This monitoring program should include plans for the collection of adequate baseline data long, continuous series of observations acquired at regular intervals when no anomalous activity is occurring in order to provide a background of values with which to contrast anomalous behavior. Efforts to collect these baseline data should proceed hand in hand with the regular monitoring activities.
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From page 75... ...
A program to monitor changes in snow and ice cover on the volcano should include visual observation, photogrammetry, infrared heat emission, and radar imagery. Staff at Mount Rainier National Park, who live and work on the volcano and are most likely to recognize anomalous changes in the ice and snow cover, should be enlisted to provide regular visual observations of the volcanic edifice.
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