On the absence of InSAR-detected volcano deformation spanning the 1995–1996 and 1999 eruptions of Shishaldin Volcano, Alaska

Moran, S. C.; Kwoun, O.; Masterlark, T.; Lü, Zhiming

doi:10.1016/j.jvolgeores.2005.07.013

Cited by 45 publications

(35 citation statements)

References 31 publications

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“…One major advance provided by InSAR data is the possibility of regional surveys, which have now been carried out at most of the Earth's major volcanic arcs (Alaska/Aleutians, Mexico/Central America, Northern-Central-SouthernAustral Andes, Indonesia & Japan). The incorporation of 'null' results into such studies has allowed global statistical demonstration of the association between deformation and eruption and the observations that some smaller volume (< VEI 3) eruptions at stratovolcanoes take place without generating measurable deformation (e.g., Pritchard & Simons, 2004, Moran et al, 2006, Ebmeier et al, 2013.…”

Section: Insights From Global Insar Volcano Deformation Measurementsmentioning

confidence: 99%

“…Although the majority of the information in the catalogue comes from publications, our intention is to provide a forum for sharing information from the 'grey' literature, including, for example, observations from otherwise unpublished student theses, conference abstracts, observatory reports and personal communications, which are allowed as references. The COMET catalogue records 'null' results -that is, a measurement of no deformation with a quantified uncertainty (or measurement threshold) over a particular time period (e.g., Moran et al, 2006;Ebmeier et al, 2013). Such data are critical for robust probabilistic analyses of links between measured deformation and outcomes in term of volcanic activity, but are rarely published.…”

Section: Data Sources: Catalogues and Databases Of Volcano Deformationmentioning

confidence: 99%

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Synthesis of global satellite observations of magmatic and volcanic deformation: implications for volcano monitoring & the lateral extent of magmatic domains

et al. 2018

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Global Synthetic Aperture Radar (SAR) measurements made over the past decades provide insights into the lateral extent of magmatic domains, and capture volcanic process on scales useful for volcano monitoring. Satellite-based SAR imagery has great potential for monitoring topographic change, the distribution of eruptive products and surface displacements (InSAR) at subaerial volcanoes. However, there are challenges in applying it routinely, as would be required for the reliable operational assessment of hazard. The deformation detectable depends upon satellite repeat time and swath widths, relative to the spatial and temporal scales of volcanological processes. We describe the characteristics of InSAR-measured volcano deformation over the past two decades, highlighting both the technique's capabilities and its limitations as a monitoring tool. To achieve this, we draw on two global datasets of volcano deformation: the Smithsonian Institution Volcanoes of the World database and the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics volcano deformation catalogue, as well as compiling some measurement characteristics and interpretations from the primary literature. We find that a higher proportion of InSAR observations capture non-eruptive and non-magmatic processes than those from ground-based instrument networks, and that both transient (< month) and long-duration (> 5 years) deformation episodes are under-represented. However, satellite radar is already used to assess the development of extended periods of unrest and long-lasting eruptions, and improved spatial resolution and coverage have resulted in the detection of previously unrecognised deformation at both ends of the spatial scale (~10 to > 1000 km 2 ). 'Baseline' records of past InSAR measurements, including 'null' results, are fundamental for any future interpretation of interferograms in terms of hazard‚ both by providing information about past deformation at an individual volcano, and for assessing the characteristics of deformation that are likely to be detectable (and undetectable) using InSAR. More than half of all InSAR deformation signals attributed to magmatic processes have sources in the shallow crust (< 5 km depth). While the depth distribution of InSAR-derived deformation sources is affected by measurement limitations, their lateral distribution provides information about the extent of active magmatic domains. Deformation is common (24% of all potentially magmatic events) at loci ≥5 km away from the nearest active volcanic vent. This demonstrates that laterally extensive active magmatic domains are not exceptional, but can comprise the shallowest part of trans-crustal magmatic systems in a range of volcanic settings.

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Section: Insights From Global Insar Volcano Deformation Measurementsmentioning

confidence: 99%

Section: Data Sources: Catalogues and Databases Of Volcano Deformationmentioning

confidence: 99%

Synthesis of global satellite observations of magmatic and volcanic deformation: implications for volcano monitoring & the lateral extent of magmatic domains

et al. 2018

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“…Such an increase may reflect an increased velocity (rate) of convection, with correspondingly faster supply of magma to the tip of the column where it can foam and degas. Seismicity and deformation in such cases are often remarkably minimal, e.g., Mayon, Philippines (Ramos-Villarta et al 1985), Shishaldin (Moran et al 2006), except if measured right at the summit/crater rim. (4) Sudden (hours-days) declines in seismicity (e.g., Newhall and Endo 1987;Endo et al 1996) and/or gas emissions (e.g., Stix et al 1993).…”

Section: Qualitative Assessments Of Eruption Likelihoodmentioning

confidence: 99%

Failed magmatic eruptions: late-stage cessation of magma ascent

2011

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When a volcano becomes restless, a primary question is whether the unrest will lead to an eruption. Here we recognize four possible outcomes of a magmatic intrusion: "deep intrusion", "shallow intrusion", "sluggish/viscous magmatic eruption", and "rapid, often explosive magmatic eruption". We define "failed eruptions" as instances in which magma reaches but does not pass the "shallow intrusion" stage, i.e., when magma gets close to, but does not reach, the surface. Competing factors act to promote or hinder the eventual eruption of a magma intrusion. Fresh intrusion from depth, high magma gas content, rapid ascent rates that leave little time for enroute degassing, opening of pathways, and sudden decompression near the surface all act to promote eruption, whereas decreased magma supply from depth, slow ascent, significant enroute degassing and associated increases in viscosity, and impingement on structural barriers all act to hinder eruption. All of these factors interact in complex ways with variable results, but often cause magma to stall at some depth before reaching the surface. Although certain precursory phenomena, such as rapidly escalating seismic swarms or rates of degassing or deformation, are good indicators that an eruption is likely, such phenomena have also been observed in association with intrusions that have ultimately failed to erupt. A perpetual difficulty with quantifying the probability of eruption is a lack of data, particularly on instances of failed eruptions. This difficulty is being addressed in part through the WOVOdat database. Papers in this volume will be an additional resource for scientists grappling with the issue of whether or not an episode of unrest will lead to a magmatic eruption.

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“…Therefore, we cannot conclusively prove or rule out the presence of volcano-wide deformation caused by magma accumulation between 1992 and 2005. The absence of pre-eruptive deformation is not uncommon, and has also been observed in Shishaldin Volcano, Alaska (e.g., Moran et al, 2006) and Lascar Volcano in Chile (e.g., Pritchard and Simons, 2002). Future work that incorporates atmospheric delays into our SVD inversion will enhance the accuracy of InSAR measurements at Augustine.…”

Section: Discussionmentioning

confidence: 77%

Deformation of the Augustine Volcano, Alaska, 1992–2005, measured by ERS and ENVISAT SAR interferometry

et al. 2008

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On the absence of InSAR-detected volcano deformation spanning the 1995–1996 and 1999 eruptions of Shishaldin Volcano, Alaska

Cited by 45 publications

References 31 publications

Synthesis of global satellite observations of magmatic and volcanic deformation: implications for volcano monitoring & the lateral extent of magmatic domains

Synthesis of global satellite observations of magmatic and volcanic deformation: implications for volcano monitoring & the lateral extent of magmatic domains

Failed magmatic eruptions: late-stage cessation of magma ascent

Deformation of the Augustine Volcano, Alaska, 1992–2005, measured by ERS and ENVISAT SAR interferometry

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