Vulcanian explosions with plumes to 12 km occurred at Soufrière Hills volcano (SHV) between July 2008 and January 2009. We report strainmeter and barometric data, featuring quasi‐linear strain changes that correlate with explosive evacuation of the conduit at rates of ∼0.9−2 × 10 7 kg s −1 . July and January explosion‐generated strains were similar, ∼20 nanostrain at ∼5 km, and interpreted as contractions of a quasi‐cylindrical conduit, with release of magmastatic pressure, and exsolution‐generated overpressure of order 10 MPa. The 3 December 2008 event was distinctive with larger signals (∼140–200 nanostrain at 5–6 km) indicating that a rapid pressurization preceded and triggered the explosion. Modeling suggests a dike with ENE trend, implying that feeder dikes at SHV had diverse attitudes at different times during the eruption. All explosions were associated with acoustic pulses and remarkable atmospheric gravity waves.

Overpressure

Dike

Seismometer

Electrical conduit

Dome (geology)

10.1029/2010gl044661

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Citations (26)

Combining Petrology and Seismology to Unravel the Plumbing System of a Typical Arc Volcano: An Example From Marapi, West Sumatra, Indonesia

Geochemistry Geophysics Geosystems (2021)

Dini Nurfiani Xin Wang Hendra Gunawan Hetty Triastuty D. Hidayat

Abstract Marapi in Sumatra is characterized by frequent short‐lived explosions and small eruptions (Volcanic Explosivity Index 1–2) and in the past 250 years, the volcano has erupted >60 times. Recent volcanic bombs and the presence of broadband seismic stations lead us to reconstruct the plumbing system of the volcano through an interdisciplinary study. A petrologic study of the summit bombs uses pyroxene, plagioclase and glass compositions to obtain pressures and temperatures of magma storage as well as identify pre‐eruptive processes. Two‐pyroxene geothermobarometry provides pre‐eruptive crystallization pressure estimates of 4–7 kbar (∼15–26 km). Compositional and textural analyses of plagioclase and pyroxene crystals indicate that mafic magma recharge was followed by mixing with the resident magma and renewed crystallization prior to eruption. In order to further image the magma reservoir, we performed a joint inversion of teleseismic receiver functions and surface waves (H/V ratio). The inversion reveals a low velocity zone (LVZ) at depths of 15–21 km that has 7 ± 3% shear velocity reduction, corresponding to an estimated melt fraction of 5 ± 2%. The depth of this LVZ overlaps with the depth of magma storage estimated from petrology, constraining it with high confidence. Such a combined interdisciplinary study provides valuable information for evaluating future periods of unrest, laying out a framework for the interpretation of incoming monitoring data and signals to look out for in order to improve eruption forecasts.

Pyroxene

Silicic

Pumice

10.1029/2020gc009524

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Citations (19)

3-D Seismic Velocity Tomography of Montserrat From the SEA-CALIPSO Offshore/Onshore Experiment.

AGUFM (2008)

E. Shalev C. L. Kenedi P. E. Malin B. Voight V. Miller

Seismic Tomography

Source

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Citations (3)