Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2004

Dixon, James P.; Stihler, Scott D.; Power, John A.; Tytgat, Guy; Estes, Steven A.; Prejean, S. G.; Sánchez, John J.; Sanches, Rebecca; McNutt, Stephen R.; Paskievitch, John F.

doi:10.3133/ofr20051312

Cited by 5 publications

(5 citation statements)

References 3 publications

(3 reference statements)

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“…Small white circles outlined in black represent seismicity spanning 2003–2008. [ Dixon et al , 2003, 2004, 2005, 2006, 2008a, 2008b]. (b) Cumulative seismicity.…”

Section: Methodsmentioning

confidence: 99%

Rheologic and structural controls on the deformation of Okmok volcano, Alaska: FEMs, InSAR, and ambient noise tomography

Masterlark¹,

Haney²,

Dickinson³

et al. 2010

J. Geophys. Res.

136

163

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[1] Interferometric synthetic aperture radar (InSAR) data indicate that the caldera of Okmok volcano, Alaska, subsided more than a meter during its eruption in 1997. The large deformation suggests a relatively shallow magma reservoir beneath Okmok. Seismic tomography using ambient ocean noise reveals two low-velocity zones (LVZs). The shallow LVZ corresponds to a region of weak, fluid-saturated materials within the caldera and extends from the caldera surface to a depth of 2 km. The deep LVZ clearly indicates the presence of the magma reservoir beneath Okmok that is significantly deeper (>4 km depth) compared to previous geodetic-based estimates (3 km depth). The deep LVZ associated with the magma reservoir suggests magma remains in a molten state between eruptions. We construct finite element models (FEMs) to simulate deformation caused by mass extraction from a magma reservoir that is surrounded by a viscoelastic rind of country rock embedded in an elastic domain that is partitioned to account for the weak caldera materials observed with tomography. This configuration allows us to reduce the estimated magma reservoir depressurization to within lithostatic constraints, while simultaneously maintaining the magnitude of deformation required to predict the InSAR data. More precisely, the InSAR data are best predicted by an FEM simulating a rind viscosity of 7.5 Â 1016 Pa s and a mass flux of À4.2 Â 10 9 kg/d from the magma reservoir. The shallow weak layer within the caldera provides a coeruption stress regime and neutral buoyancy horizon that support lateral magma propagation from the central magma reservoir to extrusion near the rim of the caldera.

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“…Small white circles outlined in black represent seismicity spanning 2003–2008. [ Dixon et al , 2003, 2004, 2005, 2006, 2008a, 2008b]. (b) Cumulative seismicity.…”

Section: Methodsmentioning

confidence: 99%

Rheologic and structural controls on the deformation of Okmok volcano, Alaska: FEMs, InSAR, and ambient noise tomography

Masterlark¹,

Haney²,

Dickinson³

et al. 2010

J. Geophys. Res.

136

163

View full text Add to dashboard Cite

show abstract

“…During and after the 2002 earthquake, all four seismic stations functioned continuously, and showed a decrease of 50% in activity (Figs 8 and 9) for 30 days in detected events and about 5 months for larger events that could be located. After March 2003 the seismicity returned to the long-term baseline where it has remained ever since (Sanchez and McNutt, 2004; Dixon and others, 2005, 2006). The 2002 earthquake was a shallow (approximately 15 km) strike slip earthquake, whereas the two previous earthquakes were deep (approximately 40 km) subduction zone earthquakes.…”

Section: Observations and Datamentioning

confidence: 95%

“…The Alaska Volcano Observatory (AVO) reduces data, and yearly catalogs are produced for locatable earthquakes (e.g. Dixon and others, 2005). These catalogs also show maps of the seismic network (see: http://www.avo.alaska.edu).…”

Section: Observations and Datamentioning

confidence: 99%

Glacier–volcano interactions in the North Crater of Mt Wrangell, Alaska

Benson¹,

Motyka²,

McNutt³

et al. 2007

Ann. Glaciol.

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Glaciological and related observations from 1961 to 2005 at the summit of Mt Wrangell (62.008 8 N, 144.028 W; 4317 m a.s.l.), a massive glacier-covered shield volcano in south-central Alaska, show marked changes that appear to have been initiated by the Great Alaska Earthquake (Mw ¼ 9.2) of 27 March 1964. The 4 Â 6 km diameter, ice-filled Summit Caldera with several post-caldera craters on its rim, comprises the summit region where annual snow accumulation is 1-2 m of water equivalent and the mean annual temperature, measured 10 m below the snow surface, is -208C. Precision surveying, aerial photogrammetry and measurements of temperature and snow accumulation were used to measure the loss of glacier ice equivalent to about 0.03 km 3 of water from the North Crater in a decade. Glacier calorimetry was used to calculate the associated heat flux, which varied within the range 20-140 W m -2 ; total heat flow was in the range 20-100 MW. Seismicity data from the crater's rim show two distinct responses to large earthquakes at time scales from minutes to months. Chemistry of water and gas from fumaroles indicates a shallow magma heat source and seismicity data are consistent with this interpretation.

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“…The oldest telemetered seismic station (ADK) in the region is located on Adak Island (Figure 1) and was installed in 1966 as part of the Global Seismic Network. Between 1999 and 2004, AVO installed seven seismic networks in central Aleutians [ Jolly et al , 2001; Dixon et al , 2003, 2004, 2005, 2006]. Each of these networks consists of 5–7 short‐period, vertical‐component sensors and one three‐component sensor.…”

Section: Seismic Network and Earthquake Detection In The Central Aleumentioning

confidence: 99%

Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: Earthquake locations and source parameters

2011

Self Cite

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[1] An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the M W 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field.

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Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2004

Cited by 5 publications

References 3 publications

Rheologic and structural controls on the deformation of Okmok volcano, Alaska: FEMs, InSAR, and ambient noise tomography

Rheologic and structural controls on the deformation of Okmok volcano, Alaska: FEMs, InSAR, and ambient noise tomography

Glacier–volcano interactions in the North Crater of Mt Wrangell, Alaska

Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: Earthquake locations and source parameters

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