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Abstract The Laguna del Maule (LdM) volcanic field comprises the greatest concentration of postglacial rhyolite in the Andes and includes the products of ~40 km3of 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‐km3shallow 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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Return From Dormancy: Rapid Inflation and Seismic Unrest Driven by Transcrustal Magma Transfer at Mt. Edgecumbe (L’úx Shaa) Volcano, Alaska
Abstract In April 2022, a seismic swarm near Mt. Edgecumbe in southeast Alaska suggested renewed activity at this transform fault volcano, which was last active ≈800 years ago. Previously, thin rhyolitic tephras were deposited 5 and 4 ka. Satellite radar data from 2014 to 2022 resolves line‐of‐sight rapid inflation up to 7.1 cm/yr beginning in August 2018. Bayesian modeling suggests a transcrustal system of a deflating (−0.528 km3) dipping sill at 20 km depth recharging a magma chamber at 10 km (0.222 km3). A near‐vertical conduit could capture the volume difference without noticeable surface deformation. Reanalyzed seismicity, recorded 25 km away, shows increases since July 2019. Magma ascent through ductile material and brittle strain release in a stressed overburden could explain the time delay. Cloud‐native open data and workflows enabled discovery and analysis of this signal within days after going unnoticed for >3 years.
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- PAR ID:
- 10376572
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 49
- Issue:
- 20
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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