The 2008 phreatomagmatic eruption of Okmok Volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes

Larsen, J. F.; Neal, Christina A.; Schaefer, J. R.; Kaufman, M.; Lü, Zhong

doi:10.14509/29405

Cited by 12 publications

(57 citation statements)

References 13 publications

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“…The two most recent eruptions of Okmok, in 1997 and2008 (VEI 3 andVEI 4, respectively), are much better documented [Larsen et al, 2015]. The 1997 eruption produced abundant ash emissions and mafic lava flows from Cone A; the 2008 eruption formed new vents near Cone D [Lu et al, 2000;Biggs et al, 2010, and references therein].…”

Section: Okmokmentioning

confidence: 99%

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

Acocella

Lorenzo

Newhall³

et al. 2015

Reviews of Geophysics

155

165

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Calderas are among the most active and dangerous volcanoes. Caldera unrest is defined by enhanced seismicity, gravity changes, surface deformation, and degassing. Although much caldera unrest does not lead to an eruption, every eruption is preceded by an unrest episode. Therefore, the proper description of unrest and the forecast of its possible outcome is a timely and challenging task. Here we review the best known unrest at calderas from 1988 to 2014, building on previous work and proposing an updated database. Where established, the root cause for unrest is always magmatic; none was purely hydrothermal or tectonic. An interpretive classification of unrest invokes two spectra-compositional (mafic to felsic) and the state of magma conduits feeding from the magma reservoir(s) to the surface (from fully plugged, through semiplugged, to open). Magma and gas in open conduits can rise and erupt freely; magma in semiplugged conduits erupts less frequently yet still allows some gas to escape; plugged conduits allow neither magma nor gas to escape. Unrest in mafic calderas is subtler, less pronounced, and repeated, especially with open systems, ensuring the continuous, aseismic, and moderate release of magma. Plugged felsic calderas erupt infrequently, anticipated by isolated, short and seismically active unrest. Semiplugged felsic calderas also erupt infrequently and are restless over decades or centuries, with uplift, seismicity, and degassing and, on the longer-term, resurgence, suggesting repeated stalled intrusions. Finally, the expected advances in better understanding caldera unrest are discussed.

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Section: Okmokmentioning

confidence: 99%

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

Acocella

Lorenzo

Newhall³

et al. 2015

Reviews of Geophysics

155

165

View full text Add to dashboard Cite

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“…The resulting deposition distribution map (Figure 3a) shows that the new cone has a diameter of 0.9 km, with its peak 253 ± 2 m above the preeruptive topography (by SRTM), at a location not far from point P1 (Figure 3a). The center of Ahmanilix, the primary vent (Larsen et al, 2015), falls exactly on the boundary between the 1997 lava flow and the Cone D bench. The preeruptive and posteruptive topography profiles along cross sections MM′ and NN′ reveal that the highest part of the crater rim of Ahmanilix formed atop a preexisting topographic rise, where the profiles intersect the prominent bench on Cone D (Figures 3b and 3c).…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, the location of a magma chamber mapped from seismic tomography data (Ohlendorf et al, 2014) and ambient noise tomography data (Masterlark et al, 2010) is deeper (depth of 4 to 6 km) than the geodetic estimates. The total eruptive volume in 2008 was 2–3 times larger than the accumulated volume between 1997 and 2008, indicating that some of the magma existed at the source before the previous eruption in 1997 (Freymueller & Kaufman, 2010), as supported by the age and composition of the erupted magma (Larsen et al, 2015).…”

Section: Introductionmentioning

confidence: 97%

“…The eruption was highly explosive due to strong magma interactions with groundwater and surface water (Lu & Dzurisin, 2010). The erupted material formed a new tephra cone (named Ahmanilix in Larsen et al (2015)) centered at the boundary between the 1997 lava flow and the Cone D bench (Figure 1c).…”

Section: Introductionmentioning

confidence: 99%

“…The coeruptive deformation of Okmok volcano in 2008 has been studied using InSAR (Lu & Dzurisin, 2010), GPS (Freymueller & Kaufman, 2010), seismic data (Johnson et al, 2010; Masterlark et al, 2010; Ohlendorf et al, 2014), the combination of GPS and InSAR (Xue et al, 2020), and field measurements (Larsen et al, 2009, 2013, 2015). InSAR observations from multiple satellite missions suggest a decrease in magma storage volume of 0.14 ± 0.01 km 3 , located at a depth of 2–3 km (Lu & Dzurisin, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the 2008 Phreatomagmatic Eruption of Okmok From ArcticDEM and InSAR: Deposition, Erosion, and Deformation

et al. 2020

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Okmok volcano, one of the most active volcanoes in the Aleutian Islands, erupted between 12 July and 19 August 2008 and produced a new tephra cone (Ahmanilix) up to 253 m high. A coeruptive deposit thickness map and the posteruptive elevation change rate map are generated for this phreatomagmatic eruption using the new, high-resolution (2 m) digital elevation model (DEM) time series provided by ArcticDEM. The total dense rock equivalent (DRE) volume over the proximal deposit field classified from the elevation change map is estimated as 0.147 ± 0.001 km 3 DRE (bulk volume of 0.453 ± 0.003 km 3). Combined with the distal deposit volume derived from field measurements, the total DRE is 0.25 km 3 (bulk volume of 0.76 km 3). The estimated erosion rate is up to −15 ± 3 m/year along the flanks of Ahmanilix, and the redeposition rate is about 1 ± 0.3 m/year at the base and 6 ± 1 m/year within the center of Ahmanilix. The surface elevation change also reveals a large ground surface collapse that disrupted the old Cone D lava bench, with a total collapse area of 0.15 km 2 and a volume of (7.1 ± 0.4) × 10 −3 km 3. We also produce a coeruptive deformation map from satellite interferometric synthetic aperture radar (InSAR) using topography from both ArcticDEM and the Shuttle Radar Topography Mission (SRTM) and compare the results. Finally, based on historical eruption volumes, the magma supply rate at Okmok is estimated as (1.77 ± 0.1) × 10 −3 km 3 /year.

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InSAR Imaging of Aleutian Volcanoes

Lü

Dzurisin

2014

InSAR Imaging of Aleutian Volcanoes

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The 2008 phreatomagmatic eruption of Okmok Volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes

Cited by 12 publications

References 13 publications

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

An overview of recent (1988 to 2014) caldera unrest: Knowledge and perspectives

Characterization of the 2008 Phreatomagmatic Eruption of Okmok From ArcticDEM and InSAR: Deposition, Erosion, and Deformation

InSAR Imaging of Aleutian Volcanoes

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