Mount St. Helens

The emption of Mount St. Helens on May 18, 1980, provided geologists with a unique opportunity to study the action of volcanos. Gas samples from the plume were collected and analyzed for toxic heavy metals. To collect mercury (Hg), gas samples were passed over a piece of gold metal, which binds Hg atoms veiy tightly. The mass of the metal increased as it absorbed Hg from the plume. From a plume-gas sample containing 200 g of ash, 3.60 ft g of Hg was deposited on the gold. How many moles of mercury were present in the gas sample How many atoms is this ... 

Volpe AM, Hammond PE (1991) U- °Th- Ra disequilibria in young Mount St. Helens rocks Time constraint for magma formation and crystallization. Earth Planet Sci Lett 107 475-486 Volpe AM, Goldstein SJ (1993) Ra- °Th disequilibrium in axial and off-axis mid-ocean ridge basalts. Geochim Cosmochim Acta 57 1233-1241... 

Information pertaining to the occurrence of cresols in surface waters was limited. STORET (1989) and the CLAPS (1988) contained no records for o-cresol in ambient surface water. o-Cresol was detected in freshwater samples from Spirit Lake, Washington, on August 7, 1980 and from South Fork Castle Lake and Smith Creek, Washington, on September 11, 1980 at unreported concentrations (McKnight et al. 1982). The presence of cresols was attributed to the Mount St. Helens eruption on May 18, 1980 (McKnight et al. 1982). Whether or not the cresols originated from wood fires or the actual eruption was not clarified. 

McKnight DM, Pereira WE, Ceazan ML, et al. 1982. Characterization of dissolved organic materials in surface waters within the blast zone of Mount St. Helens, Washington. Org Geochem 4 85-92. 

The concentration of thorium in rainwater over Fayeteville, AR, ranged from 2.8-123 fCi/L for thorium-228, 1.7-123 fCi/L for thorium-230, and 0.8-118 fCi/L for thorium-232. The peak values in thorium concentrations correlated well with the 1980 eruption of Mount St. Helen and the 1982 eruption of El Chichon (Jiang et al. 1986 Jiang and Kuroda 1987 Salaymeh and Kuroda 1987). 

Truchter JS, Robertson DE, Evans JC, et al. 1980. Mount St. Helen s ash from the 18 May 1980 eruption Chemical, physical, mineralogical, and biological properties. Science 29 1116-1125. 

Kuroda PK, Barbod T, Bakhtiar SN. 1987. Effect of the eruptions of Mount St. Helens and El Chichon on the ratios of thorium and uranium isotopes in rain. J Radioanal NucI Chem 111 137-146. 

Figure 4-30 Eruption column of Mount St. Helens, 1980. Photograph by USGS photographer of David A. Johnston Cascades Volcano Observatory, USGS, Vancouver, Washington, USA.

Cooper K.M. and Reid M.R. (2003) Reexamination of crystal ages in recent Mount St. Helens lavas implications for magma reservoir processes. Earth Planet Set. Lett. 213, 149-167. 

Rutherford M.J. and Hill P.M. (1993) Magma ascent rates from amphibole breakdown experiments and the 1980-1986 Mount St. Helens eruptions. /. Geophys. Res. 98,19667-19685. 

Figure 4-30 Plinian eruption column of Mount St. Helens...

In recent years. Znller and associates University of Maryland) have studied six active volcanoes iAugustine, Mount St. Helens. El Chiehdn. Arcnal. Poas. and Colima) and have found no evidence of lr enrichment. The new Kilauea evidence of volcanic action as an Ir source tends to conflict with that of other researchers who have generally attributed the Ir anomaly to an extraterrestrial source, such as resulting from a cataclysmic meteorite or asteroid impact, notably in connection with (he Cretaceous-Tertiary [K i t boundary layer. 

Rehabilitation of forest lands devastated by the eruptions of Mount St. Helens in May 1980 is proceeding rapidly, both by nature and by man. This paper sketches rehabilitation in the western portion of the 60,000 ha (150,000 ac) blast zone which lies to the north of the volcano. Lands in the western blast zone are primarily owned by Weyerhaeuser Company and have been managed for commercial forest crops for many decades. Rehabilitation here includes natural vegetation, camp cleanup, road reconstruction,... 

Provided new devastating volcanic events do not occur, almost complete recovery of the commercial forest lands near Mount St. Helens should be possible within the 1980 decade. Congressional legislation calls for 44,550 ha (110,000 ac) of lands near Mount St. Helens with unique features as a result of the 1980 volcanism to be preserved in a National Volcanic Monument for long-term scientific research, recreation and tourism. 

Example 14.7 The eruption of Mount St. Helens in May 1980 resulted in the aerosolization of 1 mi3 of mountaintop. If the average density of the material aerosolized was 2.6 g/cm3 and 1.0-p.m-diaineter spheres were produced, determine the number of particles produced. 

How many particles would have been produced from the eruption of Mount St. Helens (see Example 14.7) if the average density of the material was 3 g/cm3 and the particles were 0.01 pm in diameter ... 

Eine weitere Verbrennungsquelle natiirlicher Flerkunft stellen thermische Vorgange wie Waldbrande im Zusammenhang mit Vulkanausbriichen dar. So wurde von Riick-standen an PCDD und PCDF in Ascheproben des Vulkanausbruches des Mount St. Helens in den USA berichtet. 

Volcanic eruption is another natural phenomenon that may increase the concentration of natural uranium in the air. After the eruption of Mount St. Helens, increased levels of were observed in rainwater at Fayetteville, Arkansas, due to precipitation of from the atmosphere (Essien et al. 1985 Kuroda et al. 1984). Other studies indicated that long-lived natural radionuclide ( Th, Ra, and " °K) content in the ash was comparable to that of crustal material (Fruchter et al. 1980). 

Kuroda PK, Essien 10, Sandoval DN. 1984. Fallout of uranium isotopes from the 1980 eruption of Mount St. Helens. J Radioanal Nucl Chem 84 23-32. 

The 1980 eruption of Mount St. Helens was well documented although the explosive force was large, the mass of sulfur injected into the stratosphere was small and did not cause a significant increase of its optical depth (Newell and Deepak, 1982 Deepak, 1982). 

Newell R . and Deepak A., Mount St. Helens eruptions of 1980, atmospheric effects and potential climatic impact. NASA SP-458, 1982. 

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