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T. J. Casadevall

Publications and source records attributed to T. J. Casadevall.

14 recordsLinked to original sources
USGS1998

Monitoring so2 emission at the Soufriere Hills volcano: Implications for changes in eruptive conditions

Correlation spectrometer measurements of sulfur dioxide (SO 2 ) emission rates during the current eruption of the Soufriere Hills volcano, Montserrat, have contributed towards identifying different phases of volcanic activity. SO 2 emission rate has increased from <200 tonnes per day (td −1 ; <2.3 kgs −1 ) in the early stages of dome growth to >550 td −1 (>6.4 kgs −1 ) after July 1996, with the uncertainty associated with any individual measurement ca. 30%. Significantly enhanced SO 2 emission rates have been identified in association with early phreatic eruptions (800 td −1 (9.3 kgs −1 )) and episodes of vigorous dome collapse and pyroclastic flow generation (900 to 1500 td −1 (10.4 to 17.4 kgs −1 )). SO 2 emission rate has proved a useful proxy measurement for magma production rate. Observed SO 2 emission rates are significantly higher than those inferred from analyses of glass inclusions in phenocrysts, implying the existence of a S-rich magmatic vapour phase.

Geophysical Research Letters↗
USGS1998

Sulfur dioxide emission rates of Kilauea Volcano, Hawaii, 1979-1997

Sulfur dioxide (SO 2 ) emission rates from Kilauea Volcano were first measured by Stoiber and Malone (1975) and have been measured on a regular basis since 1979 (Casadevall and others, 1987; Greenland and others, 1985; Elias and others, 1993; Elias and Sutton, 1996). The purpose of this report is to present a compilation of Kilauea SO 2 emission rate data from 1979 through 1997 with ancillary meteorological data (wind speed and wind direction). We have included measurements previously reported by Casadevall and others (1987) for completeness and to improve the usefulness of this current database compilation. Kilauea releases SO 2 gas predominantly from its summit caldera and rift zones (fig. 1). From 1979 through 1982, vehicle-based COSPEC measurements made within the summit caldera were adequate to quantify most of the SO 2 emitted from the volcano. Beginning in 1983. the focus of SO 2 release shifted from the summit to the east rift zone (ERZ) eruption site at Pu'u 'O'o and, later, Kupaianaha. Since 1984, the Kilauea gas measurement effort has been augmented with intermittent airborne and tripod-based surveys made near the ERZ eruption site. In addition, beginning in 1992 vehicle-based measurements have been made along a section of Chain of Craters Road approximately 9 km downwind of the eruption site. These several types of COSPEC measurements continue to the present.

Hawaii↗
USGS1994

The 1989-1990 eruption of Redoubt Volcano, Alaska: impacts on aircraft operations

The December 1989–June 1990 eruption of Redoubt Volcano affected commercial and military air operations in the vicinity of Anchorage, Alaska. These effects were due to the direct impact of volcanic ash on jet aircraft, as well as to the rerouting and cancellations of flight operations owing to eruptive activity. Between December and February, five commercial jetliners were damaged from ash encounters. The most serious incident took place on December 15, 1989 when a Boeing 747-400 aircraft temporarily lost power of all four engines after encountering an ash cloud as the airplane descended for a landing in Anchorage. While there were no injuries to passengers, the damage to engines, avionics, and aircraft structure from this encounter is estimated at $80 million. Four additional encounters between jet aircraft and Redoubt ash clouds occurred in the Anchorage area on December 15 and 16, 1989 and February 21, 1990; none resulted in engine failure. Two additional encounters took place on December 17, 1989 when jet airliners encountered the Redoubt cloud over west Texas. At the time of these encounters, the cloud was up to 55 hours old and had traveled in excess of 2,900 nautical miles (5,300 km). Following the December 15 encounters, Anchorage International Airport remained open, however, most airline companies canceled operations for up to several days. As communications between Federal agencies and airlines improved, and as a better understanding of the nature and behavior of ash-rich eruption clouds was achieved, most airlines resumed normal service by early January 1990. The resulting loss of revenue at Anchorage International Airport during several months following the eruption is estimated to total $2.6 million. The impact on general aviation and military operations consisted mostly of cancellation and rerouting of flights.

Alaska↗
USGS1994

Emission rates of sulfur dioxide and carbon dioxide from Redoubt Volcano, Alaska during the 1989-1990 eruptions

Airborne measurements of sulfur dioxide emission rates in the gas plume emitted from fumaroles in the summit crater of Redoubt Volcano were started on March 20, 1990 using the COSPEC method. During the latter half of the period of intermittent dome growth and destruction, between March 20 and mid-June 1990, sulfur dioxide emission rates ranged from approximately 1250 to 5850 t/d, rates notably higher than for other convergent-plate boundary volcanoes during periods of active dome growth. Emission rates following the end of dome growth from late June 1990 through May 1991 decreased steadily to less than 75 t/d. The largest mass of sulfur dioxide was released during the period of explosive vent clearing when explosive degassing on December 14-15 injected at least 175,000 ?? 50,000 tonnes of SO2 into the atmosphere. Following the explosive eruptions of December 1989, Redoubt Volcano entered a period of intermittent dome growth from late December 1989 to mid-June 1990 during which Redoubt emitted a total mass of SO2 ranging from 572,000 ?? 90,000 tonnes to 680,000 ?? 90,000 tonnes. From mid-June 1990 through May 1991, the volcano was in a state of posteruption degassing into the troposphere, producing approximately 183,000 ?? 50,000 tonnes of SO2. We estimate that Redoubt Volcano released a minimum mass of sulfur dioxide of approximately 930,000 tonnes. While COSPEC data were not obtained frequently enough to enable their use in eruption prediction, SO2 emission rates clearly indicated a consistent decline in emission rates between March through October 1990 and a continued low level of emission rates through the first half of 1991. Values from consecutive daily measurements of sulfur dioxide emission rates spanning the March 23, 1990 eruption decreased in the three days prior to eruption. That decrease was coincident with a several-fold increase in the frequency of shallow seismic events, suggesting partial sealing of the magma conduit to gas loss that resulted in pressurization of the shallow magma system and an increase in earthquake activity. Unlike the short-term SO2 decrease in March 1990, the long-term decrease of sulfur dioxide emission rates from March 1990 through May 1991 was coincident with low rates of seismic energy release and was interpreted to reflect gradual depressurization of the shallow magma reservoir. The long-term declines in seismic energy release and in SO2 emission rates led AVO scientists to conclude on April 19, 1991 that the potential for further eruptive activity from Redoubt Volcano had diminished, and on this basis, the level of concern color code for the volcano was changed from code yellow (Volcano is restless; earthquake activity is elevated; activity may include extrusion of lava) to code green (Volcano is in its normal 'dormant' state). ?? 1994.

Journal of Volcanology and Geothermal Research↗
USGS1994

Evaluation of sulfur dioxide emissions from explosive volcanism: the 1982-1983 eruptions of Galunggung, Java, Indonesia

Galunggung volcano, Java, awoke from a 63-year quiescence in April 1982, and erupted sporadically through January 1983. During its most violent period from April to October, the Cikasasah Volcano Observatory reported 32 large and 56 moderate to small eruptions. From April 5 through September 19 the Total Ozone Mapping Spectrometer (TOMS), carried on NASA's Nimbus-7 satellite, detected and measured 24 different sulfur dioxide clouds; an estimated 1730 kilotons (kt) of SO2 were outgassed by these explosive eruptions. The trajectories, and rapid dispersion rates, of the SO2 clouds were consistent with injection altitudes below the tropopause. An additional 300 kt of SO2 were estimated to have come from 64 smaller explosive eruptions, based on the detection limit of the TOMS instrument. For the first time, an extended period of volcanic activity was monitored by remote sensing techniques which enabled observations of both the entire SO2 clouds produced by large explosive eruptions (using TOMS), and the relatively lower levels of SO2 emissions during non-explosive outgassing (using the Correlation Spectrometer, or COSPEC). Based on COSPEC measurements from August 1982 to January 1983, and on the relationship between explosive and non-explosive degassing, approximately 400 kt of SO2 were emitted during non-explosive activity. The total sulfur dioxide outgassed from Galunggung volcano from April 1982 to January 1983 is calculated to be 2500 kt (?? 30%) from both explosive and non-explosive activity. While Galunggung added large quantities of sulfur dioxide to the atmosphere, its sporadic emissions occurred in relatively small events distributed over several months, and reached relatively low altitudes, and are unlikely to have significantly affected aerosol loading of the stratosphere in 1982 by volcanic activity. ?? 1994.

Journal of Volcanology and Geothermal Research↗
USGS1986

Evaluation of gas data from high-temperature fumaroles at Mount St. Helens, 1980-1982

The Mount St. Helens fumarole gases show linear composition trends during periods of noneruptive degassing between September 1980 and October 1981. The trends are characterized by increasing H2O and decreasing CO2 and sulfur. Maximum fumarole temperatures also show a linear decrease during this period. High-temperature fumarole gases collected from the crater and dome between September 1980 and July 1982 are all H2O-rich (> 90%) with 1-10% CO2 and small amounts of H2S, SO2, H2, CO, HC, and HF. Trace amounts of COS and S2 are present, and occasional observations of minor CH4 appear to result from contamination or low-temperature reactions in sample vessels. The O2 fugacities of the gases remain near Ni-NiO during cooling. The low sulfur content of the gases obviates the need for extensive gas-rock oxygen exchange to maintain fO2's near Ni-NiO. A detailed thermodynamic analysis of 50 gas samples collected between September 1980 and December 1981 led to improved compositions for 22 samples. The gases were initially in a state of equilibrium, but disequilibrium modifications from atmospheric oxidation of H2 and, to a lesser extent, CO occurred within the upper portions of the fumarole vents. The last temperatures of equilibrium for the fumarole gases range from 800??C to 650??C and are nearly always higher than the collection temperatures. No evidence was found of disequilibrium admixture of surface waters; if such modifications of the fumarole gases occurred, the water must have been added at depth and have reequilibrated with the other gas species at magmatic or near-magmatic temperatures. The highest quality analytical data are obtained by field gas chromatograph measurements and from caustic soda bottle samples. Samples collected in evacuated bottles or by pumping through double stopcock tubes tend to be severely deficient in sulfur due to post-collection reactions between H2S and SO2. It is also necessary to infer the water content of the latter samples. ?? 1986.

Journal of Volcanology and Geothermal Research↗
USGS1985

Forecasts and predictions of eruptive activity at Mount St. Helens, USA: 1975-1984

Public statements about volcanic activity at Mount St. Helens include factual statements, forecasts, and predictions. A factual statement describes current conditions but does not anticipate future events. A forecast is a comparatively imprecise statement of the time, place, and nature of expected activity. A prediction is a comparatively precise statement of the time, place, and ideally, the nature and size of impending activity. A prediction usually covers a shorter time period than a forecast and is generally based dominantly on interpretations and measurements of ongoing processes and secondarily on a projection of past history. The three types of statements grade from one to another, and distinctions are sometimes arbitrary. Forecasts and predictions at Mount St. Helens became increasingly precise from 1975 to 1982. Stratigraphic studies led to a long-range forecast in 1975 of renewed eruptive activity at Mount St. Helens, possibly before the end of the century. On the basis of seismic, geodetic and geologic data, general forecasts for a landslide and eruption were issued in April 1980, before the catastrophic blast and landslide on 18 May 1980. All extrusions except two from June 1980 to the end of 1984 were predicted on the basis of integrated geophysical, geochemical, and geologic monitoring. The two extrusions that were not predicted were preceded by explosions that removed a substantial part of the dome, reducing confining pressure and essentially short-circuiting the normal precursors.

Journal of Geodynamics↗
USGS1982

Chemistry and isotope ratios of sulfur in basalts and volcanic gases at Kilauea volcano, Hawaii

Eighteen basalts and some volcanic gases from the submarine and subaerial parts of Kilauea volcano were analyzed for the concentration and isotope ratios of sulfur. By means of a newly developed technique, sulfide and sulfate sulfur in the basalts were separately but simultaneously determined. The submarine basalt has 700 ± 100 ppm total sulfur with δ 34 S Σs of 0.7 &#xB1; 0.1 &#x2030; ">‰ 0.7 ± 0.1 ‰ . The sulfate/sulfide molar ratio ranges from 0.15 to 0.56 and the fractionation factor between sulfate and sulfide is +7.5 &#xB1; 1.5&#x2030; ">‰ +7.5 ± 1.5‰ . On the other hand, the concentration and δ 34 S Σs values of the total sulfur in the subaerial basalt are reduced to 150 ± 50 ppm and &#x2212;0.8 &#xB1; 0.2&#x2030; ">‰ −0.8 ± 0.2‰ , respectively. The sulfate to sulfide ratio and the fractionation factor between them are also smaller, 0.01 to 0.25 and +3.0‰, respectively. Chemical and isotopic evidence strongly suggests that sulfate and sulfide in the submarine basalt are in chemical and isotopic equilibria with each other at magmatic conditions. Their relative abundance and the isotope fractionation factors may be used to estimate the &#x192;o 2 "> ƒo 2 and temperature of these basalts at the time of their extrusion onto the sea floor. The observed change in sulfur chemistry and isotopic ratios from the submarine to subaerial basalts can be interpreted as degassing of the SO 2 from basalt thereby depleting sulfate and 34 S in basalt. The volcanic sulfur gases, predominantly SO 2 , from the 1971 and 1974 fissures in Kilauea Crater have δ 34 S values of 0.8 to 0.9%., slightly heavier than the total sulfur in the submarine basalts and definitely heavier than the subaerial basalts, in accord with the above model. However, the δ 34 S value of sulfur gases (largely SO 2 ) from Sulfur Bank is 8.0%., implying a secondary origin of the sulfur. The δ 34 S values of native sulfur deposits at various sites of Kilauea and Mauna Loa volcanos, sulfate ions of four deep wells and hydrogen sulfide from a geothermal well along the east rift zone are also reported. The high δ 34 S values (+5 to +6%. o ) found for the hydrogen sulfide might be an indication of hot basalt seawater reaction beneath the east rift zone.

Geochimica et Cosmochimica Acta↗
USGS1981

Mt. St. Helens: evidence of increased magmatic gas component

This paper presents measurements of SO2 flux and ash leachate chemistry from Mt. St. Helens volcano during the period May 18 to July 22 which are in contrast to similar data from before May 18. Comparison of post-18 May SO2 data with similar data from other volcanoes leads to the conclusion that between 15 and 25 May the SO2 flux reached typical magmatic levels. Ash leachate chemistry from the eruption of 18 May, 22 June and 22 July also indicate a large magmatic gas component. Concentrations of Cl- and SO2-4 on May 18 ash increase with distance from the volcano and decrease with time. Leachate chemistry is used to estimate that a minimum of 2.4 ?? 105 tons of S were released on May 18. Low F concentrations on the ash, though increasing, present to health hazards. ?? 1981.

Journal of Volcanology and Geothermal Research↗