Stress interaction between magma accumulation and trapdoor faulting on Sierra Negra volcano, Galápagos

2009 ◽  
Vol 471 (1-2) ◽  
pp. 36-44 ◽  
Author(s):  
Sigurjón Jónsson
Keyword(s):  
Sierra Negra Volcano ◽  
Sierra Negra

scholarly journals Observation of cosmic ray hadrons at the top of the Sierra Negra volcano in Mexico with the SciCRT prototype

2016 ◽  
Vol 58 (10) ◽  
pp. 2018-2025
Author(s):  
E. Ortiz ◽  
J.F. Valdés-Galicia ◽  
Y. Matsubara ◽  
Y. Nagai ◽  
A. Hurtado ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Sierra Negra Volcano ◽  
Sierra Negra

The 2005 eruption of Sierra Negra volcano, Galápagos, Ecuador

2007 ◽  
Vol 70 (6) ◽  
pp. 655-673 ◽  
Author(s):  
Dennis J. Geist ◽  
Karen S. Harpp ◽  
Terry R. Naumann ◽  
Michael Poland ◽  
William W. Chadwick ◽  
...  
Keyword(s):  
Sierra Negra Volcano ◽  
Sierra Negra

Linking thermomechanical models with geodetic observations to evaluate the 2018 eruption of Sierra Negra Volcano, Galápagos

2020 ◽  
Author(s):  
Patricia Gregg ◽  
Yan Zhan ◽  
Falk Amelung ◽  
Jack Albright ◽  
Dennis Geist ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Host Rock ◽  
Volcanic Eruptions ◽  
Magma Reservoir ◽  
Tensile Failure ◽  
Model Calculations ◽  
Coulomb Failure ◽  
Magma System ◽  
Sierra Negra Volcano ◽  
Sierra Negra

<p>Ensemble based data assimilation approaches, such as the Ensemble Kalman Filter (EnKF), have been widely and successfully implemented to combine observations with dynamic models to investigate the evolution of a system’s state. Such inversions are powerful tools for providing forecasts as well as “hindcasting” events such as volcanic eruptions to investigate source parameters and triggering mechanisms. In this study, a high performance computing (HPC) adaptation of the EnKF is used to assimilate ground deformation observations from interferometric synthetic-aperture radar (InSAR) into high-fidelity, multiphysics finite element models to evaluate the prolonged unrest and June 26, 2018 eruption of Sierra Negra volcano, Galápagos. The stability of the Sierra Negra magma system is evaluated at each time step by estimating variations in reservoir overpressure, Mohr-Coulomb failure in the host rock, and tensile stress and failure along the reservoir boundary. The deformation of Sierra Negra is tracked over a decade, during which almost 5 meters of surface uplift has been recorded. The EnKF reveals that the evolution of the stress state in the host rock surrounding the Sierra Negra magma reservoir likely controlled the timing of the eruption. While increases in magma reservoir overpressure remained modest (< 10 MPa) throughout the data assimilation time period, significant Mohr-Coulomb failure is indicated in the lead up to the eruption coincident with increased seismicity along both trapdoor faults within Sierra Negra’s caldera and along the caldera’s ring faults. During the final stages of pre-eruptive unrest, the EnKF models indicate limited tensile failure, with no tensile failure along the northern portion of the magma system where the eruption commenced. Most strikingly, model calculations of significant through-going Mohr-Coulomb failure correspond in space and time with a Mw 5.4 earthquake recorded in the hours preceding the 2018 eruption. Subsequent stress modeling implicates the Mw 5.4 earthquake along the southern intra-caldera trapdoor fault as the potential catalyst for tensile failure and dike initiation along the reservoir to the north. In conclusion, the volcano EnKF approach successfully tracked the evolving stability of Sierra Negra, indicating great potential for future forecasting efforts.</p>

A volcano bursting at the seams: Inflation, faulting, and eruption at Sierra Negra volcano, Galápagos

Geology ◽  
2006 ◽  
Vol 34 (12) ◽  
pp. 1025 ◽  
Author(s):  
William W. Chadwick ◽  
Dennis J. Geist ◽  
Sigurjón Jónsson ◽  
Michael Poland ◽  
Daniel J. Johnson ◽  
...  
Keyword(s):  
Sierra Negra Volcano ◽  
Sierra Negra

4D gravity changes associated with the 2005 eruption of Sierra Negra volcano, Galápagos

Geophysics ◽  
2008 ◽  
Vol 73 (6) ◽  
pp. WA29-WA35 ◽  
Author(s):  
Nathalie Vigouroux ◽  
Glyn Williams-Jones ◽  
William Chadwick ◽  
Dennis Geist ◽  
Andres Ruiz ◽  
...  
Keyword(s):  
Melt Inclusion ◽  
Gravity Data ◽  
Mass Density ◽  
Remote Sensing Data ◽  
Gravity Anomalies ◽  
Gas Content ◽  
Residual Gravity ◽  
Caldera Floor ◽  
Sierra Negra Volcano ◽  
Sierra Negra

Sierra Negra volcano, the most voluminous shield volcano in the Galápagos archipelago and one of the largest basaltic calderas in the world, erupted on October 22, 2005 after more than [Formula: see text] of quiescence. GPS and satellite radar interferometry (InSAR) monitoring of the deformation of the caldera floor in the months prior to the eruption documented extraordinary inflation rates [Formula: see text]. The total amount of uplift recorded since monitoring began in 1992 approached [Formula: see text] at the center of the caldera over the eight days of the eruption the caldera floor deflated a maximum of 5 m and subsquently renewed its inflation, but at a decelerating rate. To gain insight into the nature of the subsurface mass/density changes associated with the deformation, gravity measurements performed in 2005, 2006, and 2007 are compared to previous measurements from 2001-2002 when the volcano underwent a period of minor deflation and magma withdrawal.The residual gravity decrease between 2001-2002 and 2005 is among the largest ever recorded atan active volcano (−950 μGal) and suggests that inflation was accompanied by a relative density decrease in the magmatic system. Forward modeling of the residual gravity data in 4D (from 2002 to 2005) gives an estimate of the amount of vesiculation in the shallow sill required to explain the observed gravity variations. Geochemical constraints from melt inclusion and satellite remote-sensing data allow us to estimate the pre-eruptive gas content of the magma and place constraints on the thickness of the gas-rich sill necessary to produce the gravity anomalies observed. Results suggest that reasonable sill thicknesses [Formula: see text] and bubble contents (10–50 volume %) can explain the large decrease in residual gravity prior to eruption. Following the eruption (2006 and 2007), the deformation and gravity patterns suggest re-equilibration of the pressure regime in the shallow magma system via a renewed influx of relatively gas-poor magma into the shallow parts of the system.

Different mechanisms of the pre- and co-eruptive tremor during the 2018 eruption at Sierra Negra volcano, Galapagos

2020 ◽  
Author(s):  
Ka Lok Li ◽  
Meysam Rezaeifar ◽  
Christopher J. Bean ◽  
James Grannell ◽  
Andrew Bell ◽  
...  
Keyword(s):  
Frequency Band ◽  
Velocity Structure ◽  
Amplitude Ratio ◽  
Volcanic Tremor ◽  
Time Lapse ◽  
P Wave ◽  
Ratio Method ◽  
Sierra Negra Volcano ◽  
Sierra Negra ◽  
Active Volcanoes

<p>Volcanic tremor are persistent seismic signals observed near active volcanoes. They are often associated with eruptions, although the exact relationships are not well constrained. To gain a better insight into the generation mechanisms of volcanic tremor, we study tremor that occurred during the 2018 eruption at Sierra Negra volcano, Galapagos. Located 1000 km west of continental Ecuador, Sierra Negra is a shield volcano with a large summit caldera and is one of the most active volcanoes in the Galapagos archipelago. The 2018 eruption started at about 19:55 UTC on 26th June and lasted about two months. Two tremor phases with very different frequency characteristics are identified before and after the eruption onset. The pre-eruptive phase is characterized by a narrow frequency band (2.5 – 4 Hz) and the co-eruptive phase has a broad frequency band (1 – 15 Hz). Location of the two phases by a seismic amplitude ratio method suggests that they are likely to be generated by different physical processes. The pre-eruptive phase is likely generated by dike opening while the co-eruptive phase is associated with lava flow. This interpretation is consistent with a time-lapse P-wave velocity structure of the volcano imaged by local-earthquake travel-time tomography.</p>

scholarly journals Stress Triggering of the 2005 Eruption of Sierra Negra Volcano, Galápagos

2018 ◽  
Vol 45 (24) ◽  
Author(s):  
P. M. Gregg ◽  
H. Le Mével ◽  
Y. Zhan ◽  
J. Dufek ◽  
D. Geist ◽  
...  
Keyword(s):  
Stress Triggering ◽  
Sierra Negra Volcano ◽  
Sierra Negra
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