Volume, energy and cyclicity of eruptions of Arenal volcano, Costa Rica

Melson, William G.; Saenz, R.

doi:10.1007/bf02597639

Cited by 73 publications

(38 citation statements)

References 9 publications

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“…The calculated volume of all LU deposits is 21.0 ± 4.0 × 10 6 m 3 . In addition, 1.8 ± 0.5 × 10 6 m 3 was estimated as the volume of the block and ash flows by Melson and Sáenz, 1973. There are contradictions in previous calculations of airfall tephra volumes, since Melson and Sáenz (1973) ascribe a volume of 40 ± 20 × 10 6 m 3 to the "airfall apron from 4 to 20 km west" and only 3 ± 1 × 10 6 m 3 to the "airfall apron from 0 to 4 km west". We infer these figures are reversed, as the lower figure roughly agrees with the estimates from scattered data by Sáenz (1977, Table 1, p. 159).…”

Section: Thickness Variation and Volume Of The Tephra Depositsmentioning

confidence: 91%

“…Therefore, it would be reasonable to assume that the distribution of fine ejecta in the present eruption is made not by wind transportation but by another dynamical mechanism". Also, Melson and Sáenz (1973) said that the nuées ardentes at Arenal produced other effects that may be viewed as the result of a "directed blast". Many beds contain intermixed vegetation and soil fragments.…”

Section: The Lu and Daumentioning

confidence: 99%

“…A quiescent interval of a couple hours before the climatic eruption could be interpreted as if the magma in the pipe had temporally fallen or became stationary. Melson and Sáenz (1973) suggested that the explosions resulted from degassing of the uppermost part of the magma column oversaturated with volatiles, or alternatively by the rising magma heating up groundwater in the permeable edifice of the volcano. Anderson (1979) reported microprobe analyses of glass inclusions in the mineral phases of one lapillus from the 1968 blast and estimated the water content of the melt to be in the approximately 7 wt.%.…”

Section: The Role Of the Structural Context And Groundwatermentioning

confidence: 99%

“…1), in Costa Rica, is one of the 16 most active volcanoes in the world (Simkin and Siebert, 2000). It has been notable for the production of pyroclastic flows since the volcano renewed its activity in 1968, following several centuries of dormancy (Melson and Sáenz, 1973;Borgia et al, 1988;Alvarado and Soto, 2002). The 1968 eruption and its disastrous effects are discussed in three widely quoted papers Sáenz, 1968, 1973;Minakami et al, 1969), and typified in several textbooks as an Ultra-Vulcaniantype eruption (Williams and McBirney, 1979) or Vulcanian type (Sigurdsson et al, 2000;Schmincke, 2004).…”

Section: Introductionmentioning

confidence: 99%

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The 1968 andesitic lateral blast eruption at Arenal volcano, Costa Rica

Alvarado

Soto

Schmincke

et al. 2006

Journal of Volcanology and Geothermal Research

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The magmatic andesitic eruption of Arenal volcano on July 29-31, 1968, after centuries of dormancy, produced three new fissural craters (A, B and C) on its western flank and a multilayered pyroclastic deposit emplaced by complex transport mechanisms. The explosions were initially triggered by a volatile oversaturated (4-7 wt.% H 2 O) magma. Several lines of evidences suggest a small blast surge, where a wood-rich pyroclastic deposit was emplaced as a ground layer, followed by several units of coarse-grained (Md Φ between −0.65 and −5.40) tephra deposits (LU: lapilli units, DAU: double ash units). LU-1, -2, -3, DAU-1 and -2 consist of unconsolidated and well-to poorly sorted vesiculated bombs and lapilli of andesite, some blocks, ash and shredded wood. The individual units are possibly correlated with the major explosions of July 29. The thickness of the deposits decreases with the distance from the volcano from 5.6 m to a few centimeters. On average, 90% of the components are juvenile (10% dense andesite and 90% vesicular). These coarse-grained beds were deposited in rapid succession by a complex transport process, involving normal fallout, strong ballistic trajectories with a lateral hot (∼400°C) blast surge (LU, equivalent to A 1 ). Ballistic and coarse tephra sprayed in a narrow (85°) area within about 5.5 km from the lowest crater, and a high (ca. 10 km) eruption column dispersed airfall fine lapilli-ash > 100 km from the volcano. Ashcloud forming explosions, producing thin pyroclastic surge and muddy phreatomagmatic fallout deposits (FLAU, equivalent to A 2 and A 3 ), closed the blast surge sequence. The successive explosions on July 30-31 mainly produced block and ash flows, and widely dispersed ash fall. The total volume of pyroclastic material is calculated as 25.8 ± 5.5 × 10 6 m 3 (9.4 ± 2.0 × 10 6 m 3 DRE). A model is proposed to explain the peculiarities of the formation, transportation and emplacement of the blast deposits. The intrusion of the presumed andesitic cryptodome possibly happened through an active thrust fault, favoring not only the formation of the lowest crater A, but also the low-angle explosive events. Prior to the eruption, several minerals were settling to the bottom of the magma chamber as is suggested by the increase of incompatible elements towards the bottom of the stratigraphic section. The major elements indicate that some crystal redistribution occurred and the maximum concentration of Al 2 O 3 , and Eu, and Sr support plagioclase enrichment in early phases of the eruption (top of LU-1 and DAU-1). From the about 20 recognized prehistoric and historic blast deposits in the world, approximately half were produced by sector collapse of the volcano and the other half by sudden decompression of cryptodomes or lava-dome collapses. The recent blasts (1888-1990s) ARTICLE IN PRESSdozen described for the previous 50 ka. Therefore, the adequate recognizers of the blast facies in the cone-building lithofacies, especially for small stratocones as described here, can help in und...

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Section: Thickness Variation and Volume Of The Tephra Depositsmentioning

confidence: 91%

Section: The Lu and Daumentioning

confidence: 99%

Section: The Role Of the Structural Context And Groundwatermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The 1968 andesitic lateral blast eruption at Arenal volcano, Costa Rica

Alvarado

Soto

Schmincke

et al. 2006

Journal of Volcanology and Geothermal Research

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“…SEM, salic end-member; MEM, mafic end-member; CEM, cumulate end-member. After Cioni, R., Civetta, L., Marianelli, P., Métrich, N., Santacroce, R. and Sbrana, A., 1995 Civetta et al, 1991;Cioni et al, 1995 2,500 Topping, 19742,287 m 187019491954195519731975Hobden et al, 1999, 2002 5 1 2,500 1,800 …”

mentioning

confidence: 99%

Advance in petrological studies on evolution of magma feeding system beneath active stratovolcanoes:

Ban

2011

Jour. Geol. Soc. Japan

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This paper reviews recent petrological studies on evolution of magma feeding system beneath active stratovolcanoes with high time resolution. Petrological studies, based on well-documented historical eruptions or detailed stratigraphy of eruptive rocks, are effective to reveal the evolution of the system. The results provide useful information for prediction of volcanic eruption.In terms of active basaltic volcanoes, these studies have revealed the structure of feeding system as well as the evolving nature of the magma chambers. The shallew chamber is replenished intermittently by more mafic magmas from the deeper part. The temporal variability of the deeper magmas was also detected. In the cases of andesitic to dacitic volcanoes, several patterns of magma evolution course have been recognized; e.g., the rapid change type within a single eruption, the cyclic change type over approximately -year intervals, and the type which remains stable over time.Most of volcanoes experience remarkable changes in the rate and explosivity of eruptions in their history. These sometimes correspond to the renewal of the magma feeding system either depth or shallow levels, or both. The renewal provides constraints on the longevity of shallow and deep magma chambers.

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On the Mechanisms of Lava Flow Emplacement and Volcano Growth: Arenal, Costa Rica

Borgia¹,

Linneman²

1990

IAVCEI Proceedings in Volcanology

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Arenal Volcano is composed of a hierarchical series of geologic units: unit flow, composite flow, lava field, and lava armor. Volume-limited unit flows are emplaced at short time intervals to make up composite flows. Composite flows form lava fields, and lava fields in turn, constitute the lava armor (the volcano). Tephra and lava breccias are selectively eroded from the steep slopes of the volcano by heavy rains and contribute little to the actual shape of the cone. This constructive process has important consequences for the distribution of the age of lava on a composite cone. We show that lava of significantly different ages may be juxtaposed at all scales from the unit flow, to the composite flow, to the lava field, and to the lava armor. These relations are applicable to the time sequential sampling of a composite volcano.Detailed observations of the dynamic behavior of unit flows indicate that two dimensionless parameters determine the distribution of lava between an active, flowing component and a passive, stationary component. The first parameter, f, is a measure of how much lava the front uses to advance relative to how much it uses to build up levees. The second parameter, q, is the fraction of lava that is able to drain out of the channel when no more lava from the vent feeds the flow. Both parameters have a primary role in determining the final dimensions of a lava flow. These parameters may be calculated from observations of lava flowing onto different topography and at different times after effusion. This data set may allow the prediction of f and q for future flows, and as a consequence, the final flow length along possible flow paths is also predictable.The development of a thermal structure within the flow plays a critical role in the dynamic evolution of a unit flow. The weight of a cold, highly viscous crust at the surface of the flow actively modifies the stress distribution in the flow and controls the rate of processes such as front velocity, levee formation, and growth of surges. We propose that for a given flux of lava there is a critical channel length beyond which the flow accelerates triggering the separation of the flow from its source near the vent. Thus, the unit flows are volume-limited. Based on this hypothesis we derive a relation for the velocity and position of the flow front at any time after effusion has started, assuming the time functions of f, q, and flow rate are known. We find that the length of a unit flow is directly proportional to f, q, and the flow rate and it is inversely proportional to the cross-sectional area of the channel and to the sine of the slope. These relations also hold for composite flows.Finally, by making the approximation that a composite flow grows to a constant slope we derive equations for the evolution of lava fields and the growth of the volcanic structure. These relations explain the asymmetric distribution, areal extent, and slope of the various lava fields at Arenal and allow us to infer the position of buried craters and contacts. Re...

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Volume, energy and cyclicity of eruptions of Arenal volcano, Costa Rica

Cited by 73 publications

References 9 publications

The 1968 andesitic lateral blast eruption at Arenal volcano, Costa Rica

The 1968 andesitic lateral blast eruption at Arenal volcano, Costa Rica

Advance in petrological studies on evolution of magma feeding system beneath active stratovolcanoes:

On the Mechanisms of Lava Flow Emplacement and Volcano Growth: Arenal, Costa Rica

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