Physics-based Models Expand Insights Gained from Volcano Geodesy
Abstract
The availability of high precision geodetic time series has increased dramatically in the recent past. Deformation data alone, however, are usually incapable of resolving important aspects of magmatic systems, including total chamber volume and melt volatile content. Independent information on magma pressure change from lava-lake level, as in the 2018 Kilauea eruption, provides much tighter constraints on chamber volume. Faulting induced deformation, such as trap-door faulting at Sierra Negra, in the Galapagos together with bounds on melt compressibility can also constrain total magma chamber volume.
Gravity change and deformation can constrain the density of the resident magma however, it is necessary to correct for gravity changes due to deformation alone - in the absence of mass addition due to flow. These changes occur due to a combination of volumetric strain and vertical displacement of layers with different density, including the free-surface. Physics-based models that predict time-varying eruptive flux and gas emissions, together with deformation can place tighter constraints on important system parameters. Making use of time-dependent gas emission requires understanding the pathways that volatiles take to the surface. The ratio of eruptive flux to deformation rate yields the scaled compressibility (magma plus chamber) of the system; the latter depends on chamber shape as well as crustal stiffness. In many cases flux and deformation decay roughly exponentially, reflecting nearly time-invariant compressibility, which places further constraints on pressure changes given solubility relations. Seismicity and deformation are the most widely used geophysical measurements used for forecasting eruptions, yet they are rarely interpreted together in a quantitative fashion. Stress changes near propagating dike tips and surface deformations reflect the same magmatic processes. Deformation is sensitive mainly to large spatial scales while earthquakes reflect local stresses and frictional properties. Simplified seismicity rate models have made considerable progress in reconciling geodetic and seismic data.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.G31A..01S
- Keywords:
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- 1240 Satellite geodesy: results;
- GEODESY AND GRAVITY;
- 1295 Integrations of techniques;
- GEODESY AND GRAVITY;
- 8485 Remote sensing of volcanoes;
- VOLCANOLOGY