Inflation and deflation at the steep-sided Llaima stratovolcano (Chile) detected by using InSAR

Bathke, H.; Shirzaei, Manoochehr; Walter, Thomas R.

doi:10.1029/2011gl047168

Cited by 27 publications

(26 citation statements)

References 18 publications

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“…The potential range of positions for the 2007–2008 Central American explosions is shown as a gray box in Figure a and is based on the assumption that any associated volume change was less than 10 −4 km 3 , the maximum volume change expected for a VEI 2 eruption. Even if explosions at San Cristóbal, Poás, and Telica (2007–2009) were associated with the deflation and subsequent recharge of shallow reservoirs, differing from the 2011 Telica eruption described above, the volume changes (<10 −4 km 3 ) would have been among the lowest measured with InSAR (e.g., Llaima and Slamet) [ Bathke et al ., ; Philibosian and Simons , ].…”

Section: Comparison To Eruptive Recordmentioning

confidence: 99%

On the lack of InSAR observations of magmatic deformation at Central American volcanoes

et al. 2013

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A systematic survey of 3 years of L band interferometric synthetic aperture radar (InSAR) measurements of the Central American Volcanic Arc shows a striking lack of magmatic deformation. We make measurements at 20 of the 26 historically active volcanoes and demonstrate that none were deforming magmatically (2007–2010), although we do measure shallow subsidence associated with flow deposits and edifice loading at three volcanoes. The minimum detection rates for our survey, as estimated from the variance in time series of radar path delay, are relatively high due to strong variability of tropospheric water vapor. We compare the average detection threshold (2.4 cm/yr) to published InSAR measurements and show that the majority (~78%) of deformation events would have been measurable with the same level of noise as Central America. We calculate that if magmatic volcano deformation were spread evenly across historically active volcanoes worldwide, the probability of none of Central America's 26 volcanoes deforming would be < 1%. The lack of magmatic deformation in Central America may be indicative of differences in magma storage relative to other well‐studied continental arcs. The high proportion of basalts that ascend directly from depth relative to andesites stored in the shallow crust may limit the potential for high magnitude deformation. Magma stored in vertically elongated reservoirs and high parental melt volatile contents that result in bubble‐rich, compressible magmas at shallow depths may also reduce surface deformation. We consider the measurement and analysis of a lack of deformation at active volcanoes to be essential for realizing the potential of regional scale InSAR surveys.

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Section: Comparison To Eruptive Recordmentioning

confidence: 99%

On the lack of InSAR observations of magmatic deformation at Central American volcanoes

et al. 2013

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“…In contrast, some volcanoes show long-lived subsidence following an eruption. Lliama volcano (Chile) subsided over 3.5 years following an eruption in 2003 (Girona et al 2014), which was attributed to post-eruptive outgassing (Bathke et al 2011). Some post-eruption magmatic processes do not result in geodetic signals at the surface.…”

Section: Introductionmentioning

confidence: 99%

What causes subsidence following the 2011 eruption at Nabro (Eritrea)?

Hamlyn¹,

Wright

Walters

et al. 2018

Prog Earth Planet Sci

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A major goal in volcanology is to be able to constrain the physical properties of a volcanic system using surface observations. The behaviour of a volcanic system following an eruption can provide powerful constraints on these properties and can provide valuable information for understanding future hazard. We use spatially and temporally dense observations of surface deformation following the 12 June 2011 eruption of Nabro (Eritrea) to place constraints on the mechanics of its subsurface volcanic system. Nabro was imaged 129 times by TerraSAR-X and COSMO-SkyMed satellites during a 15-month period following the eruption. We have produced a detailed time series of the line-of-sight (LOS) displacements at Nabro, finding that the volcano subsides during the entire observation period at a decaying rate. We found significant atmospheric artefacts remained in the data set after a standard spatio-temporal filter was applied. Applying an empirical correction using a linear phase-elevation relationship removed artefacts but also removed real topographically correlated deformation. Instead, we were able to correct each SAR acquisition using independent delay estimates derived from the ECMWF ERA-Interim (ERA-I) global atmospheric model. The corrected time series can be modelled with the deflation of a Mogi source at ∼ 6.4 ± 0.3 km depth. Modelling the time series using viscoelastic relaxation of a shell which surrounds a spherical magma chamber can explain the observed subsidence without a source of further volume loss if the magma is compressible. CO 2 outgassing is also a possible cause of continued subsidence. Contraction due to cooling and crystallisation, however, is probably minor. If any post-eruptive recharge of the magmatic system at Nabro is occurring, the rate of recharge must be slower than the post-eruptive relaxation processes. Combined with the lack of pre-eruptive inflation, we suggest that recharge of the magmatic system at Nabro either occurs at a rate that is slower than our detection limit, or it occurs episodically. This case study demonstrates the power of long, dense geodetic time series at volcanoes.

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“…Another example of depressurization during passive degassing is found in Llaima volcano (Chile), where subsidence of the volcanic edifice on the order of 10 7 m 3 was recorded during three years and a half (from November 2003 to May 2007) before a fast inflation lasting for six months and the onset of an eruption [Bathke et al, 2011]. The subsidence is consistent with the volume decrease predicted for the reservoir by our model assuming elastic or viscoelastic rheology for the crust (see Figure 2b).…”

Section: Discussionmentioning

confidence: 99%

On depressurization of volcanic magma reservoirs by passive degassing

et al. 2014

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Many active volcanoes around the world alternate episodes of unrest and mildly explosive eruptions with quiescent periods dominated by abundant but passive gas emissions. These are the so-called persistently degassing volcanoes, and well-known examples are Mayon (Philippines) and Etna (Italy). Here, we develop a new lumped-parameter model to investigate by how much the gas released during quiescence can decrease the pressure within persistently degassing volcanoes. Our model is driven by the gas fluxes measured with monitoring systems and takes into account the size of the conduit and reservoir, the viscoelastic response of the crust, the magma density change, the bubble exsolution and expansion at depth, and the hydraulic connectivity between reservoirs and deeper magma sources. A key new finding is that, for a vast majority of scenarios, passive degassing reduces the pressure of shallow magma reservoirs by several MPa in only a few months or years, that is, within the intereruptive timescales of persistently degassing volcanoes. Degassing-induced depressurization could be responsible for the subsidence observed at some volcanoes during quiescence (e.g., at Satsuma-Iwojima and Asama, in Japan; Masaya, in Nicaragua; and Llaima, in Chile), and could play a crucial role in the onset and development of the physical processes which may in turn culminate in new unrest episodes and eruptions. For example, degassing-induced depressurization could promote magma replenishment, induce massive and sudden gas exsolution at depth, and trigger the collapse of the crater floor and reservoir roof.

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Inflation and deflation at the steep-sided Llaima stratovolcano (Chile) detected by using InSAR

Cited by 27 publications

References 18 publications

On the lack of InSAR observations of magmatic deformation at Central American volcanoes

On the lack of InSAR observations of magmatic deformation at Central American volcanoes

What causes subsidence following the 2011 eruption at Nabro (Eritrea)?

On depressurization of volcanic magma reservoirs by passive degassing

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