scholarly journals Ground deformation measurements over Lake Trichonis based on SAR interferometry.

2016 ◽  
Vol 47 (3) ◽  
pp. 1071
Author(s):  
G. Benekos ◽  
I. Parcharidis ◽  
M. Foumelis ◽  
A. Ganas
Keyword(s):  
Seismic Activity ◽  
Structural Model ◽  
Ground Deformation ◽  
Earthquake Swarm ◽  
Sar Interferometry ◽  
Normal Faults ◽  
Deformation Pattern ◽  
Small Magnitude ◽  
Envisat Asar ◽  
Seismic Triggering

The aim of this study is to detect and measure ground deformation over the broader area of Lake Trichonis (Western Greece), focusing mainly on the April 2007 earthquake swarm which occurred at the vicinity of the Lake. The area, forming a pull-apart basin, presented historically an intense seismic activity along the two active normal faults at the northern and southern part of the Lake. The swarminitiated by small magnitude events on the 8th of April 2007 followed by the three strongest events of the entire sequence on the 10th of April 2007, with magnitudes ranging from 5.0 to 5.2 Mw. The seismic activity continued for longer with smaller seismic events. Based on seismological data this activity was attributed to two unmapped NW SE trending normal faults that bounds the SE bank of the Lake. Using a dataset of 28 ENVISAT ASAR scenes covering the period from February 2003 until February 2010 (~7 yr), different Interferometric Stacking techniques was applied in order to quantify the ground deformation induced by the earthquake swarm as well as its effect on the inter-seismic deformation pattern of the area. Our results indicate that co-seismic motion differs significantly from that observedduring the pre- and post- swarm periods. The co-seismic pattern reveals subsidence at the northern and uplift at the southern lake sides, consistent with the structural model already proposed for the area. For the pre- and post-seismic periods both sides of the Lake show stability or low rates of subsidence with higher deformationvelocity rates for the period after the seismic activity, possibly attributed to postseismic relaxation. Our findings imply that inter-seismic ground deformation does not necessary follow the deformation pattern observed during seismic triggering, thus, long-term geodetic observations such as those provided by SAR interferometry are valuable in order to fully characterize the geodynamic behavior of an active region.

scholarly journals Spatio-temporal evolution of aseismic ground deformation in the Mexicali Valley (Baja California, Mexico) from 1993 to 2010, using differential SAR interferometry

2015 ◽  
Vol 372 ◽  
pp. 335-341 ◽  
Author(s):  
O. Sarychikhina ◽  
E. Glowacka
Keyword(s):  
Deformation Rate ◽  
Baja California ◽  
Temporal Evolution ◽  
Ground Deformation ◽  
Geothermal Field ◽  
Sar Interferometry ◽  
Deformation Pattern ◽  
Ground Fissures ◽  
Spatio Temporal ◽  
Cerro Prieto

Abstract. Ground deformation in Mexicali Valley, Baja California, Mexico, the southern part of the Mexicali-Imperial valley, is influenced by active tectonics and human activity, mainly that of geothermal fluid extraction in the Cerro Prieto Geothermal Field. Significant ground deformation, mainly subsidence (~ 18 cm yr−1), and related ground fissures cause severe damage to local infrastructure. The technique of Differential Synthetic Aperture Radar Interferometry (DInSAR) has been demonstrated to be a very effective remote sensing tool for accurately measuring the spatial and temporal evolution of ground displacements over broad areas. In present study ERS-1/2 SAR and ENVISAT ASAR images acquired between 1993 and 2010 were used to perform a historical analysis of aseismic ground deformation in Mexicali Valley, in an attempt to evaluate its spatio-temporal evolution and improve the understanding of its dynamic. For this purpose, the conventional 2-pass DInSAR was used to generate interferograms which were used in stacking procedure to produce maps of annual aseismic ground deformation rates for different periods. Differential interferograms that included strong co-seismic deformation signals were not included in the stacking and analysis. The changes in the ground deformation pattern and rate were identified. The main changes occur between 2000 and 2005 and include increasing deformation rate in the recharge zone and decreasing deformation rate in the western part of the CPGF production zone. We suggested that these changes are mainly caused by production development in the Cerro Prieto Geothermal Field.

scholarly journals The 2013 earthquake swarm in Helike, Greece: seismic activity at the root of old normal faults

2015 ◽  
Vol 202 (3) ◽  
pp. 2044-2073 ◽  
Author(s):  
V. Kapetanidis ◽  
A. Deschamps ◽  
P. Papadimitriou ◽  
E. Matrullo ◽  
A. Karakonstantis ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Earthquake Swarm ◽  
Normal Faults

Multiparametric monitoring of the ongoing eruption of Sangay volcano, Ecuador

2021 ◽  
Author(s):  
Francisco Javier Vasconez ◽  
Silvana Hidalgo ◽  
Stephen Hernández ◽  
Josué Salgado ◽  
Sébastien Valade ◽  
...  
Keyword(s):  
Lava Flow ◽  
Seismic Activity ◽  
Ground Deformation ◽  
Monitoring Network ◽  
Deformation Pattern ◽  
Density Currents ◽  
Eruptive Activity ◽  
Data Set ◽  
Eruptive Style ◽  
Eruptive Episode

<p>During the last two decades, Sangay has been one of the most active Ecuadorian volcanoes. However, because of its remote location and logistically difficult access, monitoring Sangay is a challenging task. The IG-EPN tackled this problem by expanding its terrestrial monitoring network and complementing it with the available satellite data. On 7<sup>th</sup> May 2019, the most recent and ongoing eruptive episode commenced. Compared to the previously monitored and observed eruptive activity at Sangay since the 2000’s, this episode is by far the most intense and the first to affect populated areas due to ash fallouts and numerous lahars. Surface activity is generally characterized by frequent low-to-moderate magnitude ash emissions and a semi-continuous viscous lava flow extrusion. This activity is punctuated by occasional lava flow collapse events, probably associated with pulses of high lava extrusion and that produced long-runout pyroclastic density currents towards the southeastern flank.</p><p>Here, we present the most complete data set of long-term instrumental observations performed at Sangay. SO<sub>2</sub> degassing, seismic activity, ground deformation, ash emissions and thermal anomalies are depicted as a multiparametric sequence to better understand the link between these parameters and the dynamism and eruptive style of this isolated volcano.  </p><p>Correlations between the depicted parameters are not straight-forward, making it hard to identify patterns that might lead to enhanced eruptive activity. High values of SO<sub>2</sub> recorded by the DOAS instruments as well as the TROPOMI satellite sensor seem to coincide with periods of increased eruption rate. Nevertheless, increases in SO<sub>2</sub> flux do not occur systematically before or after these episodes. Seismic activity, characterized by daily counts of individual seismic events, does not demonstrated a clear precursory pattern either. These results indicate that none of the available monitoring parameters currently allow for a timely forecast of the largest and potentially most dangerous eruptions. However, looking at the entire time series we are able to distinguish a slightly but progressive change in the ground deformation displacement associated with a higher number of earthquakes per day prior to the 20 September 2020 paroxysmic event. This eruption produced regional ash fallout which affected significant swaths of farming lands and livestock. Since then, a different ground deformation pattern has taken hold, and coincides with a step decrease in the number of daily earthquakes and a significant increase in the SO<sub>2</sub> mass measured by TROPOMI.</p><p>This behavior matches an open-vent system, where punctual increases in eruptive activity show few precursory signals. The observed increase in all the parameters compared to previous eruptions before 2019 allows us to propose that this eruptive phase is fed by batches of deep and volatile-rich magma which rise to the surface at high ascent rates. The interpretations presented here are an important step towards a better understanding of the dynamism and eruptive style of this very active and isolated volcano. Moreover, the various monitoring parameters from terrestrial to satellite provide a better picture of the behavior of Sangay that could be applied to other remote and open-system volcanoes.</p>

Simulation of Instant and Delayed Seismic Triggering Observed After the 30 October 2020 Samos Earthquake at Nearby Faults

2021 ◽  
Author(s):  
Eyup Sopaci ◽  
Atilla Arda Özacar
Keyword(s):  
Normal Stress ◽  
Failure Time ◽  
Active Faults ◽  
Strong Motion ◽  
Strike Slip ◽  
Static Stress ◽  
Normal Faults ◽  
Small Magnitude ◽  
Seismic Triggering ◽  
Stress Changes

<p>The 30 October 2020 Samos Earthquake (Mw=7.0) ruptured a north-dipping offshore normal fault, north of the Samos Island with an extensional mechanism. Aftershocks mainly occurred at the western and eastern ends of the rupture plane in agreement with the Coulomb static stress changes. Mechanism of aftershocks located west of the rupture area supported activation of the neighboring strike-slip fault almost instantly. In addition, a seismic cluster including events with magnitudes reaching close to 4 has emerged fifty hours later at the SE side of Samos Island. This off-plane cluster displays a clear example of delayed seismic triggering that produced small magnitude earthquakes at nearby active faults. In this study, numerical simulations are conducted using rate-and-state friction dependent quasi-static&full-dynamic spring slider model with shear-normal stress coupling to mimic the instant and delayed seismic triggering observed after this event. Coulomb static stress changes and seismic waveforms recorded at nearby strong-motion stations are used as static and dynamic triggers during simulations. According to our results, earthquakes with Mw<3.5 can be triggered almost instantly at the rupture edge and failure time of earthquakes with Mw>3.5 advances for both strike-slip and normal faults which may explain the delayed triggering observed SE of Samos Island. Moreover, simulations revealed that the shear-normal stress coupling increases the triggering potential.</p>

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

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

<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>This work was financially supported by the “Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile” (Presidency of the Council of Ministers – Department of Civil Protection); this publication, however, does not reflect the position and official policies of the Department".</p>

Displacements around Two Closely Adjacent Circular Openings

2012 ◽  
Vol 170-173 ◽  
pp. 1397-1401
Author(s):  
Li Yan ◽  
Jun Sheng Yang
Keyword(s):  
Boundary Condition ◽  
Deformation Mechanism ◽  
Ground Deformation ◽  
Ground Surface ◽  
Deformation Pattern ◽  
Measured Field ◽  
Ground Loss ◽  
Computer Package ◽  
Convergence Model ◽  
Surface Settlements

Deformations of the tunnels may results in settlements of the ground surface. Based on the characters of deformation of twin closely adjacent tunnels excavated, a basic deformation mechanism of two parallel tunnels constructed close together was present, which is not uniform but oval-shaped ground deformation pattern and represent the ground loss occurred during construction of the tunnels. An improved convergence model of the tunnel boundary for twin closely adjacent tunnels and the related expressions are proposed. Using a computer package FLAC2D, the certain given deformations as the boundary condition were applied to the boundaries of two tunnels, and the surface settlements caused by the excavation of two tunnels were obtained. It is found that the results match well with the measured field results.

scholarly journals Tectonic stress regime in the 2003–2004 and 2012–2015 earthquake swarms in the Ubaye Valley, French Alps

2018 ◽  
Vol 175 (6) ◽  
pp. 1997-2008 ◽  
Author(s):  
Lucia Fojtíková ◽  
Václav Vavryčuk
Keyword(s):  
Seismic Activity ◽  
Joint Inversion ◽  
Earthquake Swarm ◽  
Active Faults ◽  
Tectonic Stress ◽  
Geological Mapping ◽  
Earthquake Swarms ◽  
Stress Regime ◽  
French Alps ◽  
Principal Axes

Abstract We study two earthquake swarms that occurred in the Ubaye Valley, French Alps within the past decade: the 2003–2004 earthquake swarm with the strongest shock of magnitude ML = 2.7, and the 2012–2015 earthquake swarm with the strongest shock of magnitude ML = 4.8. The 2003–2004 seismic activity clustered along a 9-km-long rupture zone at depth between 3 and 8 km. The 2012–2015 activity occurred a few kilometres to the northwest from the previous one. We applied the iterative joint inversion for stress and fault orientations developed by Vavryčuk (2014) to focal mechanisms of 74 events of the 2003–2004 swarm and of 13 strongest events of the 2012–2015 swarm. The retrieved stress regime is consistent for both seismic activities. The σ 3 principal axis is nearly horizontal with azimuth of ~ 103°. The σ 1 and σ 2 principal axes are inclined and their stress magnitudes are similar. The active faults are optimally oriented for shear faulting with respect to tectonic stress and differ from major fault systems known from geological mapping in the region. The estimated low value of friction coefficient at the faults 0.2–0.3 supports an idea of seismic activity triggered or strongly affected by presence of fluids.

SpaCeborne SAR Interferometry as a Noninvasive tool to assess the vulnerability over Cultural hEritage sites (SCIENCE)

2021 ◽  
Author(s):  
Athanasia-Maria Tompolidi ◽  
Issaak Parcharidis ◽  
Constantinos Loupasakis ◽  
Michalis Fragkiadakis ◽  
Pantelis Soupios ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Cultural Heritage ◽  
Ming Dynasty ◽  
Ground Deformation ◽  
Sar Interferometry ◽  
Archaeological Sites ◽  
Science Project ◽  
Heritage Sites ◽  
Persistent Scatterers ◽  
Great Wall

<p>Cultural heritage is a key element of history as the ancient monuments and archaeological sites enrich today’s societies and help connect us to our cultural origins. The project entitled ''SpaCeborne SAR Interferometry as a Nonivasive tool to assess the vulnerability over Cultural hEritage sites (SCIENCE)'' has as ultimate objective to predict the vulnerability of the archaeological sites to ground deformation in time and space and protect them against natural/man-made damage. The SCIENCE project aims to develop, demonstrate, and validate, in terms of geotechnical local conditions and monuments’ structural health, SAR interferometric techniques to monitor potential ground deformation affecting the archaeological sites and monuments of great importance. </p><p>During the last few years, spaceborne Synthetic Aperture Radar (SAR) interferometry has proven to be a powerful remote sensing tool for detecting and measuring ground deformation and studying the deformation’s impact on man-made structures. It provides centimeter to millimeter resolution and even single buildings/monuments can be mapped from space. Considering the limitations of conventional MT-InSAR techniques, such as Persistent Scatterers Interferometry (PSI), in this project a two-step Tomography-based Persistent Scatterers (PS) Interferometry (Tomo-PSInSAR) approach is proposed for monitoring ground deformation and structural instabilities over the Ancient City Walls (Ming Dynasty) in Nanjing city, China and in the Great Wall in Zhangjiakou, China. The Tomo-PSInSAR is capable of separating overlaid PS in the same location, minimizing the unfavorable layover effects of slant-range imaging in SAR data. Moreover, the demonstrations are performed on well-known test sites in China and in Greece, such as: a) Ming Dynasty City Walls in Nanjing, b) Great Wall in Zhangjiakou, c) Acropolis complex of Athens and d) Heraklion walls (Crete Island), respectively.</p><p>In particular, in the framework of SCIENCE project are processed several radar datasets such as Sentinel 1 A & B data of Copernicus program and the high resolution TerraSAR-X data. The products of Persistent Scatterers Interferometry (PSI) are exported in various formats for the identification of the persistent scatterers using high resolution optical images, aerial photographs and fusing with high accuracy Digital Surface Models (DSM). In addition, the validation of the results is taking place through in-situ measurements (geological, geothechnical e.t.c) and data for the cultural heritage sites conditions.</p><p>SCIENCE project’s final goal is the risk assessment analysis of the cultural heritage monuments and their surrounding areas aiming to benefit institutions, organizations, stakeholders and private agencies in the cultural heritage domain through the creation of a validated pre-operation non-invasive system and service based on earth observation data supporting end-user needs by the provision knowledge about cultural heritage protection. In conclusion, SCIENCE project is composed by a bilateral consortium of the Greek delegation of Harokopio University of Athens, National Technical University of Athens, Terra Spatium S.A, Ephorate of Antiquities of Heraklion (Crete), Acropolis Restoration Service (Athens) of Ministry of Culture and Sports and by the Chinese delegation of Science Academy of China (Institute of Remote Sensing and Digital Earth) and  International Centre on Space Technologies for Natural and Cultural Heritage (HIST) under the auspices of UNESCO (HIST-UNESCO).</p>

scholarly journals Ice-shelf dynamics near the front of the Filchner-Ronne Ice Shelf, Antaretica, revealed by SAR interferometry: model/interferogram comparison

1998 ◽  
Vol 44 (147) ◽  
pp. 419-428 ◽  
Author(s):  
Douglas R MacAyeal ◽  
Eric Rignot ◽  
Christina L Hulbe
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Sar Interferometry ◽  
Deformation Pattern ◽  
Ice Shelf ◽  
Mechanical Coupling ◽  
Iceberg Calving ◽  
Shelf Dynamics ◽  
Coastal Boundary ◽  
Shelf Flow

AbstractWe compare European remote-sensing satellite (ERS) synthetic aperture radar interferograms with artificial interferograms constructed using output of a finite-element ice-shelf flow model to study the dynamics of Filchner-Ronne Ice Shelf (FRIS), Antaretica, near Hemmen Ice Rise (HIR) where the iceberg-calving front intersects Berkner Island. We find that the model must account for rifts, mechanically competent sea ice which fills rifts, and ice softening in coastal boundary layers in order to agree with the ice-deformation pattern implied by observed interferograms. Analysis of the stress field in the model experiment that best matches the observed interferograms suggests that: (1) HIR introduces weakness into the ice shelf through the generation of large-scale rifts, and (2) the melange of sea ice and ice-shelf fragments that fills the rifts stabilizes the shelf front by providing mechanical coupling between the fractured shelf front and the adjacent coast. The rift-filling melange could melt more easily than the surrounding ice shelf and thus could represent a vulnerability of the FRIS to climate warming.

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