Glacier–volcano interactions deduced by SAR interferometry

AbstractGlacier-surface displacements produced by geothermal and volcanic activity beneath Vatnajökull ice cap in Iceland are described by field surveys of the surface topography combined with interferograms acquired from repeat-pass synthetic aperture radar images. A simple ice-flow model serves well to confirm the basic interpretation of the observations. The observations cover the period October 1996–January 1999 and comprise: (a) the ice-flow field during the infilling of the depressions created by the subglacial Gjálp eruption of October 1996, (b) the extent and displacement of the floating ice cover of the subglacier lakes of Grímsvötn and the Skaftá cauldrons, (c) surface displacements above the subglacier pathways of the jökulhlaups from the Gjálp eruption site and the Grímsvötn lake, (d) detection of areas of increased basal sliding due to lubrication by water, and (e) detection of spots of temporal displacement that may be related to altering subglacial volcanic activity. At the depression created by the Gjálp eruption, the maximum surface displacement rate away from the radar decreased from 27 cm d−1 to 2 cm d−1 over the period January 1997–January 1999. The observed vertical displacement of the ice cover of Grímsvötn changed from an uplift rate of 50 cm d−1 to sinking of 48 cm d−1, and for Skaftá cauldrons from 2 cm d to 25 cm d−1.

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ESTIMATION OF SURFACE DEFORMATION DUE TO PASNI EARTHQUAKE USING SAR INTERFEROMETRY

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-3-23-2018 ◽

2018 ◽

Vol XLII-3 ◽

pp. 23-29 ◽

Cited By ~ 1

Author(s):

M. Ali ◽

M. I. Shahzad ◽

M. Nazeer ◽

J. H. Kazmi

Keyword(s):

Strong Earthquake ◽

Surface Deformation ◽

Sea Water ◽

Ground Deformation ◽

Surface Displacement ◽

Vertical Displacement ◽

Sar Interferometry ◽

Building Structures ◽

Major Surface ◽

Ground Displacements

Earthquake cause ground deformation in sedimented surface areas like Pasni and that is a hazard. Such earthquake induced ground displacements can seriously damage building structures. On 7 February 2017, an earthquake with 6.3 magnitudes strike near to Pasni. We have successfully distinguished widely spread ground displacements for the Pasni earthquake by using InSAR-based analysis with Sentinel-1 satellite C-band data. The maps of surface displacement field resulting from the earthquake are generated. Sentinel-1 Wide Swath data acquired from 9 December 2016 to 28 February 2017 was used to generate displacement map. The interferogram revealed the area of deformation. The comparison map of interferometric vertical displacement in different time period was treated as an evidence of deformation caused by earthquake. Profile graphs of interferogram were created to estimate the vertical displacement range and trend. Pasni lies in strong earthquake magnitude effected area. The major surface deformation areas are divided into different zones based on significance of deformation. The average displacement in Pasni is estimated about 250&thinsp;mm. Maximum pasni area is uplifted by earthquake and maximum uplifting occurs was about 1200&thinsp;mm. Some of areas was subsidized like the areas near to shoreline and maximum subsidence was estimated about 1500&thinsp;mm. Pasni is facing many problems due to increasing sea water intrusion under prevailing climatic change where land deformation due to a strong earthquake can augment its vulnerability.

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Estimating surface displacement in the Hanshin area, Japan, by PS-InSAR analysis using satellite Sentinel-1 data

10.5194/egusphere-egu21-10472 ◽

2021 ◽

Author(s):

Yutaro Shigemitsu ◽

Kazuya Ishitsuka ◽

Weiren Lin

Keyword(s):

Fault Zone ◽

Groundwater Level ◽

Active Faults ◽

Surface Displacement ◽

Sar Interferometry ◽

Surface Displacements ◽

Active Segment ◽

2018 Northern Osaka Earthquake ◽

Groundwater Level Changes

The 2018 northern Osaka earthquake with a magnitude 6.1 earthquake struck on June 18, 2018 in northern Osaka, causing enormous damage. SAR interferometry using satellite synthetic aperture radar (SAR) data can detect surface displacement distribution over a wide area and is effective for observing surface displacement during an earthquake. On the other hand, it is also important to observe the tendency of long-term surface displacement around active faults on a yearly basis in order to monitor the deformation at and around active faults. In this study, we used persistent scatter SAR interferometry (PS-InSAR) to clarify the recent surface displacement including before and after the 2018 northern Osaka earthquake near the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment, near the epicenter of the earthquake. PS-InSAR analysis is a method that analyzes coherent pixels only, and can extract surface displacements with less noise than the conventional two-pass SAR interferometry. By using Sentinel-1 data, we expect to understand a long-term surface displacement and temporal changes in displacement pattern by comparing with the results using other satellites in previous studies. As a result of our analysis, we found that (i) ground subsidence occurred near the Mt. Rokko active segment, (ii) subsidence or eastward displacement occurred in the eastern part of the Takarazuka GNSS station, (iii) surface displacement in the wedge-shaped area located between the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment is suggested to be caused by groundwater level changes, (iv) groundwater level changes may have caused surface displacement considered to be uplift in the wide area between the Ikoma Fault Zone and Uemachi Fault Zone, and (v) slip of the source fault may have caused surface displacement around the epicenter of the 2018 northern Osaka earthquake. Furthermore, we validated the estimated surface displacements by comparison with GNSS measurements and previous studies. These results suggest that surface displacement near the Arima-Takatsuki fault zone was caused by the 2018 northern Osaka earthquake. In order to reveal the mechanism of surface displacement in the vicinity of the fault, it is necessary to continue to monitor the surface displacement in this area using time-series SAR interferometry.&#160;&#160;We acknowledge Sentinel-1 data provided from the European Space Agency (ESA) based on the open data policy.

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Iceberg calving rates from northern Ellesmere Island ice caps, Canadian Arctic, 1999–2003

Journal of Glaciology ◽

10.3189/002214308785837048 ◽

2008 ◽

Vol 54 (186) ◽

pp. 391-400 ◽

Cited By ~ 29

Author(s):

Scott Williamson ◽

Martin Sharp ◽

Julian Dowdeswell ◽

Toby Benham

Keyword(s):

Glacier Surface ◽

Ice Flow ◽

Ice Caps ◽

Ice Cap ◽

Glacier Terminus ◽

Devon Ice Cap ◽

Order Of Magnitude ◽

Iceberg Calving ◽

Flow Through ◽

Calving Rate

AbstractOptical satellite imagery was used to estimate glacier surface velocities and iceberg calving rates from Agassiz and western Grant Ice Caps, Nunavut, Canada, between 1999 and 2003. The largest mean annual surface velocities ranged from ∼400 to 700 m a−1, but velocities in the ∼100–200 m a−1 range were common. Summer velocities were up to an order of magnitude larger than annually averaged velocities. The highest velocity (∼1530 m a−1) was measured on the floating tongue of Lake Tuborg Glacier between 19 July and 19 August 2001. Calving rates from individual glaciers varied by up to a factor of two between successive years. Summer calving rates were ∼2–8 times larger than annual average rates. The average ratio of the calving flux due to terminus-volume change to that due to ice flow through the glacier terminus was ∼0.81 for the annual rates and ∼1.71 for summer rates. The estimated mean annual calving rate from Agassiz Ice Cap in the period 1999–2002 was 0.67 ± 0.15 km3 a−1, of which ∼54% emanated from Eugenie Glacier alone. This total rate is similar to a previously estimated calving rate from Devon Ice Cap.

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A high-frequency and high-resolution image time series of the Gornergletscher – Swiss Alps – derived from repeated UAV surveys

10.5194/essd-2018-145 ◽

2018 ◽

Cited By ~ 1

Author(s):

Lionel Benoit ◽

Aurelie Gourdon ◽

Raphaël Vallat ◽

Inigo Irarrazaval ◽

Mathieu Gravey ◽

...

Keyword(s):

Feature Detection ◽

Detection Algorithm ◽

Swiss Alps ◽

Glacier Surface ◽

Ice Flow ◽

Ice Surface ◽

Surface Displacements ◽

Drainage Networks ◽

Digital Elevation ◽

Very High Spatial Resolution

Abstract. The rapid growth of drone technology provides an efficient means to monitor the response of alpine glaciers to climate warming. Here we report a new dataset based on images collected during ten intensive UAV surveys of the Gornergletscher glacial system (Switzerland) carried out approximately every two weeks throughout the summer 2017. The final products, available at: https://doi.org/10.5281/zenodo.1487862 (Benoit et al, 2018), consist in a series of 10 cm resolution ortho-images, Digital Elevation Models of the glacier surface, and Matching Maps that can be used to quantify ice surface displacements and velocities. Used on its own, this dataset allows mapping the glacier and monitoring surface velocities over the summer at a very high spatial resolution. Coupled with a classification or feature detection algorithm, it enables extracting structures such as surface drainage networks, debris or snow cover. The approach we present can be used in the future to gain insights into ice flow dynamics.

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Surface velocity and ice discharge of the ice cap on King George Island, Antarctica

Annals of Glaciology ◽

10.3189/2013aog63a517 ◽

2013 ◽

Vol 54 (63) ◽

pp. 111-119 ◽

Cited By ~ 37

Author(s):

B. Osmanoğlu ◽

M. Braun ◽

R. Hock ◽

F.J. Navarro

Keyword(s):

Weighted Average ◽

Large Mass ◽

Surface Velocity ◽

King George Island ◽

Ice Flow ◽

Radar Images ◽

Ice Cap ◽

Ice Surface ◽

Air Temperatures

AbstractGlaciers on King George Island, Antarctica, have shown retreat and surface lowering in recent decades, concurrent with increasing air temperatures. A large portion of the glacier perimeter is ocean-terminating, suggesting possible large mass losses due to calving and submarine melting. Here we estimate the ice discharge into the ocean for the King George Island ice cap. L-band synthetic aperture radar images covering the time-span January 2008 to January 2011 over King George Island are processed using an intensity-tracking algorithm to obtain surface velocity measurements. Pixel offsets from 40 pairs of radar images are analysed and inverted to estimate a weighted average surface velocity field. Ice thicknesses are derived from simple principles of ice flow mechanics using the computed surface velocity fields and in situ thickness data. The maximum ice surface speeds reach >225 m a-1, and the total ice discharge for the analysed flux gates of King George Island is estimated to be 0.720 ± 0.428 Gt a−1, corresponding to a specific mass loss of 0.64 ± 0.38 m w.e. a-1 over the area of the entire ice cap (1127 km2).

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Spatiotemporal behavior of a large-scale landslide at Mt. Onnebetsu-dake, Japan, detected by three L-band SAR satellites

Earth Planets and Space ◽

10.1186/s40623-020-01265-4 ◽

2020 ◽

Vol 72 (1) ◽

Author(s):

Youichiro Takada ◽

George Motono

Keyword(s):

Large Scale ◽

Fluid Pressure ◽

Surface Displacement ◽

Length Change ◽

Vertical Displacement ◽

Phase Changes ◽

Annual Rainfall ◽

Spatiotemporal Behavior ◽

Spatially Periodic ◽

L Band

Abstract We applied differential InSAR analysis to the Shiretoko Peninsula, northeastern Hokkaido, Japan. All the interferograms of long temporal baseline (~ 3 years) processed from SAR data of three L-band satellites (JERS-1, ALOS, ALOS-2) commonly indicate remarkable phase changes due to the landslide movement at the southeastern flank of Mt. Onnebetsu-dake, a Quaternary stratovolcano. The area of interferometric phase change matches to known landslide morphologies. Judging from the timing of the SAR image acquisitions, this landslide has been moving at least from 1993 to the present. Successive interferograms of 1-year temporal baseline indicate the temporal fluctuation of the landslide velocity. Especially for the descending interferograms, the positive line-of-sight (LOS) length change, which indicates large subsidence relative to the horizontal movement, is observed in the upslope section of the landslide during 1993–1998, while the negative LOS change is observed in the middle and the downslope section after 2007 indicating less subsidence. The landslide activity culminates from 2014 to 2017: the eastward and the vertical displacement rates reach ~ 6 and ~ 2 cm/yr, respectively. Utilizing high spatial resolution of ALOS and ALOS-2 data, we investigated velocity distribution inside the landslide. During 2007–2010, the eastward component of surface displacement increases toward the east, implying that the landslide extends toward the east. During 2014–2017, the vertical displacement profile exhibits spatially periodic uplift and subsidence consistent with surface gradient, which indicates the ongoing deformation driven by gravitational force. Heavy rainfall associated with three typhoons in August 2016 might have brought about an increase in the landslide velocity, possibly due to elevated pore-fluid pressure within and/or at the base of the landslide material. Also, annual rainfall would be an important factor that prescribes the landslide velocity averaged over 3 years.

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Vulnerability Assessment of Buildings due to Land Subsidence Using InSAR Data in the Ancient Historical City of Pistoia (Italy)

Sensors ◽

10.3390/s20102749 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2749 ◽

Cited By ~ 8

Author(s):

Pablo Ezquerro ◽

Matteo Del Soldato ◽

Lorenzo Solari ◽

Roberto Tomás ◽

Federico Raspini ◽

...

Keyword(s):

Fragility Curves ◽

Central Italy ◽

Sar Interferometry ◽

Ground Subsidence ◽

Public And Private ◽

Radar Images ◽

Spatial Deformation ◽

Damage Probability ◽

Medium Resolution ◽

Vertical Displacements

The launch of the medium resolution Synthetic Aperture Radar (SAR) Sentinel-1 constellation in 2014 has allowed public and private organizations to introduce SAR interferometry (InSAR) products as a valuable option in their monitoring systems. The massive stacks of displacement data resulting from the processing of large C-B and radar images can be used to highlight temporal and spatial deformation anomalies, and their detailed analysis and postprocessing to generate operative products for final users. In this work, the wide-area mapping capability of Sentinel-1 was used in synergy with the COSMO-SkyMed high resolution SAR data to characterize ground subsidence affecting the urban fabric of the city of Pistoia (Tuscany Region, central Italy). Line of sight velocities were decomposed on vertical and E–W components, observing slight horizontal movements towards the center of the subsidence area. Vertical displacements and damage field surveys allowed for the calculation of the probability of damage depending on the displacement velocity by means of fragility curves. Finally, these data were translated to damage probability and potential loss maps. These products are useful for urban planning and geohazard management, focusing on the identification of the most hazardous areas on which to concentrate efforts and resources.

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Site information and initial results from deep ice drilling on Law Dome, Antarctica

Journal of Glaciology ◽

10.3189/s0022143000002768 ◽

1997 ◽

Vol 43 (143) ◽

pp. 3-10 ◽

Cited By ~ 10

Author(s):

V.I. Morgan ◽

C.W. Wookey ◽

J. Li ◽

T.D. van Ommen ◽

W. Skinner ◽

...

Keyword(s):

Ice Core ◽

Ice Sheet ◽

High Accumulation ◽

Ice Flow ◽

Ice Cap ◽

Basal Ice ◽

Inland Ice ◽

The Last Glacial Maximum ◽

Initial Results ◽

The Last Glacial

AbstractThe aim of deep ice drilling on Law Dome, Antarctica, has been to exploit the special characteristics of Law Dome summit, i.e. low temperature and high accumulation near an ice divide, to obtain a high-resolution ice core for climatic/environmental studies of the Holocene and the Last Glacial Maximum (LGM). Drilling was completed in February 1993, when basal ice containing small fragments of rock was reached at a depth of 1196 m. Accurate ice dating, obtained by counting annual layers revealed by fine-detail δ18О, peroxide and electrical-conductivity measurements, is continuous down to 399 m, corresponding to a date of AD 1304. Sulphate concentration measurements, made around depths where conductivity tracing indicates volcanic fallout, allow confirmation of the dating (for Agung in 1963 and Tambora in 1815) or estimates of the eruption date from the ice dating (for the Kuwae, Vanuatu, eruption ~1457). The lower part of the core is dated by extrapolating the layer-counting using a simple model of the ice flow. At the LGM, ice-fabric measurements show a large decrease (250 to 14 mm2) in crystal size and a narrow maximum in c-axis vertically. The main zone of strong single-pole fabrics however, is located higher up in a broad zone around 900 m. Oxygen-isotope (δ18O) measurements show Holocene ice down to 1113 m, the LGM at 1133 m and warm (δ18O) about the same as Holocene) ice near the base of the ice sheet. The LGM/Holocene δ18O shift of 7.0‰, only ~1‰ larger than for Vostok, indicates that Law Dome remained an independent ice cap and was not overridden by the inland ice sheet in the Glacial.

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Remote sensing of steep-slope volcanoes: the Stromboli case study

10.5194/egusphere-egu21-9539 ◽

2021 ◽

Author(s):

Federico Di Traglia ◽

Claudio De Luca ◽

Alessandro Fornaciai ◽

Mariarosaria Manzo ◽

Teresa Nolesini ◽

...

Keyword(s):

Remote Sensing ◽

Volcanic Activity ◽

Ground Deformation ◽

Steep Slope ◽

Sar Interferometry ◽

Large Set ◽

Multi Temporal ◽

Optical Imagery ◽

Gravitational Processes ◽

Sciara Del Fuoco

Steep-slope volcanoes are geomorphological systems receptive to both exogenous and endogenous phenomena. Volcanic activity produces debris and lava accumulation, whereas magmatic/tectonic and gravitational processes can have a destructive effect, triggering mass-wasting and erosion.Optical and radar sensors have often been used to identify areas impacted by eruptive and post-eruptive phenomena, quantify of topographic changes, and/or map ground deformation related to magmatic-tectonic-gravitational processes.In this work, the slope processes on high-gradient volcano flanks in response to shift in volcanic activity have been identified by means of remote sensing techniques. The Sciara del Fuoco unstable flank of Stromboli volcano (Italy) was studied, having a very large set (2010-2020) of different remote sensing data available.Data includes LiDAR and tri-stereo PLEIADES-1 DEMs, high-spatial-resolution (HSR) optical imagery (QUICKBIRD and PLEIADES-1), and space-borne and ground-based Synthetic Aperture Radar (SAR) data. Multi-temporal DEMs and HSR optical imagery permits to map areas affected by major lithological and morphological changes, and the volumes of deposited/eroded material. The results lead to the identification of topographical variations and geomorphological processes that occurred in response to the variation in eruptive intensity. The joint exploitation of space-borne and ground-based Differential and Multi Temporal SAR Interferometry (InSAR and MT-InSAR) measurements revealed deformation phenomena affecting the volcano edifice, and in particular the Sciara del Fuoco flank.The presented results demonstrate the effectiveness of the joint exploitation of multi-temporal DEMs, HSR optical imagery, and InSAR measurements obtained through satellite and terrestrial SAR systems, highlighting their strong complementarity to map and interpret the slope phenomena in volcanic areas.This work was financially supported by the &#8220;Presidenza del Consiglio dei Ministri &#8211; Dipartimento della Protezione Civile&#8221; (Presidency of the Council of Ministers &#8211; Department of Civil Protection); this publication, however, does not reflect the position and official policies of the Department".

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Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland

The Cryosphere ◽

10.5194/tc-11-741-2017 ◽

2017 ◽

Vol 11 (2) ◽

pp. 741-754 ◽

Cited By ~ 31

Author(s):

Monika Wittmann ◽

Christine Dorothea Groot Zwaaftink ◽

Louise Steffensen Schmidt ◽

Sverrir Guðmundsson ◽

Finnur Pálsson ◽

...

Keyword(s):

Mass Balance ◽

Radiative Forcing ◽

Climate Model ◽

Dispersion Model ◽

Dust Deposition ◽

Glacier Surface ◽

Outlet Glacier ◽

Ice Cap ◽

Weather Stations ◽

Dust Events

Abstract. Deposition of small amounts of airborne dust on glaciers causes positive radiative forcing and enhanced melting due to the reduction of surface albedo. To study the effects of dust deposition on the mass balance of Brúarjökull, an outlet glacier of the largest ice cap in Iceland, Vatnajökull, a study of dust deposition events in the year 2012 was carried out. The dust-mobilisation module FLEXDUST was used to calculate spatio-temporally resolved dust emissions from Iceland and the dispersion model FLEXPART was used to simulate atmospheric dust dispersion and deposition. We used albedo measurements at two automatic weather stations on Brúarjökull to evaluate the dust impacts. Both stations are situated in the accumulation area of the glacier, but the lower station is close to the equilibrium line. For this site ( ∼  1210 m a.s.l.), the dispersion model produced 10 major dust deposition events and a total annual deposition of 20.5 g m−2. At the station located higher on the glacier ( ∼  1525 m a.s.l.), the model produced nine dust events, with one single event causing ∼  5 g m−2 of dust deposition and a total deposition of ∼  10 g m−2 yr−1. The main dust source was found to be the Dyngjusandur floodplain north of Vatnajökull; northerly winds prevailed 80 % of the time at the lower station when dust events occurred. In all of the simulated dust events, a corresponding albedo drop was observed at the weather stations. The influence of the dust on the albedo was estimated using the regional climate model HIRHAM5 to simulate the albedo of a clean glacier surface without dust. By comparing the measured albedo to the modelled albedo, we determine the influence of dust events on the snow albedo and the surface energy balance. We estimate that the dust deposition caused an additional 1.1 m w.e. (water equivalent) of snowmelt (or 42 % of the 2.8 m w.e. total melt) compared to a hypothetical clean glacier surface at the lower station, and 0.6 m w.e. more melt (or 38 % of the 1.6 m w.e. melt in total) at the station located further upglacier. Our findings show that dust has a strong influence on the mass balance of glaciers in Iceland.

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