Crustal seismicity associated to rpid surface uplift at Laguna del Maule Volcanic Complex, Southern Volcanic Zone of the Andes

Cardona, Carlos; Tassara, Andrés Ollero; Gil-Cruz, Fernando; Lara, Luis E.; Morales, Sergio; Kohler, Paulina; Franco, Luis

doi:10.1016/j.jvolgeores.2018.01.009

Cited by 25 publications

(51 citation statements)

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“…Petrologic constraints suggest that the accumulation of fluids derived from intruding magma may be an important mechanism by which rhyolite eruptions have been triggered at LdM (Andersen et al, 2018). The occurrence of earthquake swarms and longperiod earthquakes (Cardona et al, 2018) as well as diffuse CO 2 soil degassing is also consistent with the presence of magmatic fluids. Thus, the ongoing unrest may capture the growth and possibly the destabilization of a potentially large, rhyolitic upper crustal magma reservoir that could culminate in eruption .…”

Section: 1029/2018jb016485mentioning

confidence: 73%

Magma Reservoir Below Laguna del Maule Volcanic Field, Chile, Imaged With Surface‐Wave Tomography

et al. 2019

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The Laguna del Maule (LdM) volcanic field comprises the greatest concentration of postglacial rhyolite in the Andes and includes the products of ~40 km3 of explosive and effusive eruptions. Recent observations at LdM by interferometric synthetic aperture radar and global navigation satellite system geodesy have revealed inflation at rates exceeding 20 cm/year since 2007, capturing an ongoing period of growth of a potentially large upper crustal magma reservoir. Moreover, magnetotelluric and gravity studies indicate the presence of fluids and/or partial melt in the upper crust near the center of inflation. Petrologic observations imply repeated, rapid extraction of rhyolitic melt from crystal mush stored at depths of 4–6 km during at least the past 26 ka. We utilize multiple types of surface‐wave observations to constrain the location and geometry of low‐velocity domains beneath LdM. We present a three‐dimensional shear‐wave velocity model that delineates a ~450‐km3 shallow magma reservoir ~2 to 8 km below surface with an average melt fraction of ~5%. Interpretation of the seismic tomography in light of existing gravity, magnetotelluric, and geodetic observations supports this model and reveals variations in melt content and a deeper magma system feeding the shallow reservoir in greater detail than any of the geophysical methods alone. Geophysical imaging of the LdM magma system today is consistent with the petrologic inferences of the reservoir structure and growth during the past 20–60 kyr. Taken together with the ongoing unrest, a future rhyolite eruption of at least the scale of those common during the Holocene is a reasonable possibility.

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Section: 1029/2018jb016485mentioning

confidence: 73%

Magma Reservoir Below Laguna del Maule Volcanic Field, Chile, Imaged With Surface‐Wave Tomography

et al. 2019

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“…The Mogi source from the combined inversion (yellow star, Figure b) is colocated with a region of elevated conductivity. The depth and duration of the deformation, in addition to the coincident elevated conductivities, and occurrence of seismicity suggest that the source is magmatic (Cardona et al, ; Heise et al, ; Lu et al, ).…”

Section: Discussionmentioning

confidence: 99%

Sustained Uplift at a Continental Rift Caldera

et al. 2018

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Caldera systems are often restless and experience pulses of uplift and subsidence, with a weak, but significant link to eruption. Characterizing the spatial and temporal patterns of deformation episodes provides insight into the processes responsible for unrest and the architecture of magmatic and hydrothermal systems. Here we combine interferometric synthetic aperture radar images with data from Global Positioning System and a network of seismometers at a continental rift caldera Corbetti, Ethiopia. We document inflation that started mid‐2009 and is ongoing as of 2017, with associated seismicity. We investigate the temporal evolution of the deformation source using a Hastings‐Metropolis algorithm to estimate posterior probability density functions for source model parameters and use the Akaike information criterion to inform model selection. Testing rectangular dislocation and point sources, we find a point source at a depth of 6.6 km (95% confidence: 6.3 − 6.8 km) provides the statistically justified fit. The location of this source is coincident with a conductive anomaly derived from magnetotelluric measurements. We use a joint inversion of two geodetic data sets to produce a time series, which shows a volume input of 1.0 × 107 m3/year. This is the first observation of a prolonged period of magma reservoir growth in the Main Ethiopian Rift and has implications for hazard assessment and monitoring. Corbetti is < 20 km from two major population centers and has estimated return periods of ∼500 and ∼900 years for lava flows and Plinian eruptions, respectively. Our results highlight the need for long‐term geodetic monitoring and the application of statistically robust methods to characterize deformation sources.

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“…Therefore, earthquakes at a distance from the magma reservoir cannot be triggered. However, shallower earthquakes are also observed (Cardona et al, 2018), which indicates the fluid may also inject upward. This observation agrees with the volumetric strain calculation, since more "dilatancy" occurs at the shallow depth with the fault zone (Figure 8c), which is also The colored stars show the stress direction from the focal mechanism of the well-located VT events (Cardona et al, 2018).…”

Section: "Hydrofracturing" Processmentioning

confidence: 99%

“…A variety of geophysical methods have been applied to evaluate the location and architecture of the LdM magma system (Figure b), including gravity (Miller, Williams‐Jones, et al, ), magnetotellurics (MT; Cordell et al, ), and seismic tomography (Wespestad et al, ). Additionally, recent microgravity (Miller, Le Mével, et al, ) and seismicity (Cardona et al, ) investigations suggest that fluid migration coinciding with the Troncoso fault zone may be interacting with the magma reservoir during the recent unrest episode. However, the potential hydrothermal system is not visible through any hydrothermal surface activities (Andersen et al, ) or ground deformation (Le Mével et al, ).…”

Section: Introductionmentioning

confidence: 99%

Integrating Reservoir Dynamics, Crustal Stress, and Geophysical Observations of the Laguna del Maule Magmatic System by FEM Models and Data Assimilation

et al. 2019

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The Laguna del Maule volcanic field is a large rhyolitic magmatic system in the Chilean Andes, which has exhibited frequent eruptions during the past 20 ka. Rapid surface uplift (>20 cm/year) has been observed since 2007 accompanied by localized earthquake swarms and microgravity changes, indicating the inflating magma reservoir may interact with a preexisting weak zone (i.e., Troncoso fault). In this investigation, we model the magma reservoir by data assimilation with Interferometric Synthetic Aperture Radar data. The reservoir geometry is comparable to the magma body inferred by seismic tomography, magnetotelluric, and gravity studies. The models also suggest that a weak zone, which has little effect on surface displacement, is important as a fluid transport channel to promote earthquakes and microgravity changes. In particular, concentrated dilatancy within the weak zone facilitates the microfracture formation during reservoir inflation. High‐pressure fluid can inject into the weak zone from the magma reservoir to trigger earthquakes and further migrate upward to create positive gravity changes by occupying unsaturated storages. The pore pressure will then decrease, halting the seismicity swarm until the next cycle. This “hydrofracturing” process may release some accumulated stress along the magma reservoir delaying an eventual eruption in turn. Besides, the resultant models are propagated forward in time to evaluate potential stress trajectories for future unrest.

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Crustal seismicity associated to rpid surface uplift at Laguna del Maule Volcanic Complex, Southern Volcanic Zone of the Andes

Cited by 25 publications

References 25 publications

Magma Reservoir Below Laguna del Maule Volcanic Field, Chile, Imaged With Surface‐Wave Tomography

Magma Reservoir Below Laguna del Maule Volcanic Field, Chile, Imaged With Surface‐Wave Tomography

Sustained Uplift at a Continental Rift Caldera

Integrating Reservoir Dynamics, Crustal Stress, and Geophysical Observations of the Laguna del Maule Magmatic System by FEM Models and Data Assimilation

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