This suggests that they are associated with the repeating rupture of asperities surrounded by aseismic slip. These events have both highly similar waveforms and quasi-periodic recurrence times. Most "repeating icequakes" on glaciers have been detected at the base of glaciers or ice streams (see references on l36-38). However, I don't think that this term is correct in this context, and I think it can be misleading. The term "repeating icequakes" or "repeaters" is present in many places in the manuscript, starting from the title. I found that some results are not always very convincing (eg, back-azimuth from signal polarization) or some interpretations are rather speculative (basal slip?). Micro-seismicity analysis and coda wave interferometry have been used by aiming at evaluating the temporal evolution of seismic indicators, such icequakes rate, relative seismic velocity and attenuation.Ī major break-off event occurred at the end of the monitoring period, inviting the identification of precursors before the event for improving early warning systems.Īlthough the technical challenge of seismic instrumentation, the main interest of the study lies in the investigation of physical processes in the subsurface of a hanging glacier, as a complementary method to forecasting technology focusing only the surface. The authors recorded seismic data and used sophisticated methods to extract a lot of information from icequakes signals. This article proposes a seismological study of a hanging glacier in Swiss Alps, which has been instrumented during five months in 2016. The proposed approach extends the monitoring of the hanging glacier beyond the ice surface and allows for a better understanding of the glacier’s response to time-dependent external forcing, which is an important step towards improved break-off forecasting systems. Diurnal cycles of Qc −1, repeating icequake activity, and the velocity of the glacier front shift from cosinusoidal to sinusoidal variations under the presence of meltwater. Comparison of dv/ v and Q c with air temperature suggests that these changes are driven by a seasonal increase in the glacier’s ice and firn pack temperature that might affect the top 20 m of the glacier. Our results show a seasonal 0.1 % decrease in relative englacial seismic velocity dv/ v and an increase in coda wave attenuation Qc −1 ( Q c decreases from ~50 to ~30). We propose a novel approach for hanging glacier monitoring by combining repeating icequake analysis, coda wave interferometry, and attenuation measurements. It recorded over 200,000 repeating icequakes showing strong englacial seismic coda waves. A single seismometer operated throughout the whole monitoring period.
Among different instruments, such as an automatic camera and interferometric radar, four 3-component seismometers were installed on the glacier. The Eiger hanging glacier, located in the Swiss Alps, was intensely monitored between April and August 2016 before a moderate 15,000 m 3 break-off event from the ice cliff. Reliable forecasting remains a challenge as englacial damage leading to large-scale failure is masked from modern sensing technology focusing on the ice surface. "At" icon by FreePik from Driven by the force of gravity, hanging glacier instabilities can lead to catastrophic rupture events.Icons used in the XML Tree View are used under the Creative Commons 3.0 BY license.
#Coda 2 xml full#
xmlTools.xqueryExecutionEngine: The full path to the executable to run when executing XQuery scripts.ĭetailed release notes are available here.xmlTools.xqueryExecutionArguments: Arguments to be passed to the XQuery execution engine.xmlTools.xmlFormatterImplementation: Supported XML Formatters: classic, v2.
xmlTools.splitXmlnsOnFormat: Put each xmlns attribute on a new line when formatting XML.Overrides xmlTools.splitXmlnsOnFormat if set to true. xmlTools.splitAttributesOnFormat: Put each attribute on a new line when formatting XML.xmlTools.removeCommentsOnMinify: Remove XML comments during minification.xmlTools.persistXPathQuery: Remember the last XPath query used.xmlTools.ignoreDefaultNamespace: Ignore default xmlns attributes when evaluating XPath.xmlTools.enforcePrettySelfClosingTagOnFormat: Ensures a space is added before the forward slash at the end of a self-closing tag.xmlTools.enableXmlTreeViewCursorSync: Enables auto-reveal of elements in the XML Document view when a start tag is clicked in the editor.xmlTools.enableXmlTreeViewMetadata: Enables attribute and child element counts in the XML Document view.xmlTools.enableXmlTreeView: Enables the XML Tree View for XML documents.
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