Characterizing near‐field surface deformation in the 1990 Rudbar earthquake (Iran) using optical image correlation

2021 ◽  
Author(s):  
Najmeh Ajorlou ◽  
James Hollingsworth ◽  
Zahra Mousavi ◽  
Abdolreza Ghods ◽  
Zohreh Masoumi
Keyword(s):  
Surface Deformation ◽  
Near Field ◽  
Optical Image ◽  
Image Correlation

Comparison between the coseismic surface displacement during the 29 December 2020 Mw 6.4 Petrinja earthquake (Croatia) from optical image correlation and long-term geomorphological observations of cumulative displacements

2021 ◽  
Author(s):  
Maxime Henriquet ◽  
Adrien Moulin ◽  
Matija Vukovski ◽  
Branko Kordić ◽  
Marko Budić ◽  
...  
Keyword(s):  
Lateral Displacement ◽  
Near Field ◽  
Surface Displacement ◽  
Primary Component ◽  
Strike Slip ◽  
Optical Image ◽  
Image Correlation ◽  
Field Analysis ◽  
Fault System ◽  
Event Image

<p>The Petrinja-Pokupsko fault-system is a NW-SE right-lateral fault system that ruptured during the 29 December 2020 Mw 6.4 earthquake (~40km south-east of Zagreb, Croatia). Field analysis revealed opening of cracks and offsets of several centimeters (3 to 40 cm) along a ~20 km long fault zone extending from the Kupa river (in the northwest) to the Petrinjčica river (in the southeast). Optical image correlation based on WorldView satellite images has been used to document the first-order near-field rupture signal. The pre-event image was acquired on 7th December 2017, and the post-event image on 15th January 2021. The first results indicate a right-lateral displacement of ≈75 cm with a small (<10 cm) extensional dip-slip component localized on the Petrinja fault. Using 1:5,000 topographic maps, a WorldView-derived DEM (1 m), and field observations, we identified and quantified cumulative dextral offsets along the central and southern section of the fault (south of Župić). Right-lateral offsets range from 5 to 200 m near Križ and Cepeliš (central sector). Diverted streams also extend southeast of the Petrinjčica river, where no surface ruptures have currently been reported to date. To the northwest, perched valleys, wind gaps, and karst features all testify to ongoing uplift across NW-SE-trending anticlines. It is unclear if the primary component of faulting changes from strike-slip (in the SE) to reverse (in the NW), or if these folds merely record a transpressive component across the fault. The activity of this fault system is poorly known. The region experienced a magnitude Mw 5.8 in 1909, ~30 km northwest of Petrinja, which may have been associated with the Petrinja-Pokupsko fault system. The recent 29 December 2020 earthquake confirms the seismic potential of this fault system to generate Mw>6 earthquakes. Since the fault extends farther NW and SE, from the Vukomeričke Gorice hills to Mount Kozara (Bosnia), for a total length of about 100 km, it could generate potentially larger events. It is also noteworthy that the 2020 Petrinja event occurred only 9 months after the Zagreb March 2020 (Mw 5.3) earthquake. This event occurred on an ENE-WSW-trending thrust fault, broadly orthogonal to the right-lateral Petrinja-Pokupsko fault system, ~45 km north of Petrinja, and raises the prospect of potential interplay between strike-slip and thrust faults in moderate strain-rate intra-plate settings. To address this problem, future works will aim at constraining the geometry of this fault network and its seismogenic potential.</p>

New 3D constraints on the co-seismic displacement field for the 1959 (Mw 7.2) Hebgen Lake earthquake from optical image correlation of historical aerial images

2021 ◽  
Author(s):  
Lucia Andreuttiova ◽  
James Hollingsworth ◽  
Pieter Vermeesch ◽  
Thomas Mitchell
Keyword(s):  
Displacement Field ◽  
Near Field ◽  
Damage Zone ◽  
Historical Earthquakes ◽  
Optical Image ◽  
Image Correlation ◽  
Aerial Images ◽  
Aerial Photographs ◽  
Normal Faults ◽  
Small Scale

<p>Optical image correlation (OIC) is a powerful tool for measuring the 3-D near-field surface displacements produced in large earthquakes. The method compares pre- and post-earthquake orthorectified images; shifts between common pixels in the image pair reflects a 2-D (horizontal) offset. The third dimension (vertical displacement) is calculated by differencing the pre- and post-topography, while accounting for the horizontal displacements. Optical image correlation has a sub-pixel detection capability<!-- Everywhere, not just close to the rupture -->, and can provide information on the displacement field close to fault ruptures (where InSAR typically decorrelates). Small-scale measurements of the distributed damage provide important constraints on the strain distribution within the fault core and the surrounding damage zone, as well as offering insights into the rupture mechanics.</p><p>OIC is frequently applied to the recent earthquakes where the image footprint is large relative to the rupture extents. However, historical ruptures are documented by aerial photographs which cover a relatively small area. This means that many images are needed to cover the rupture area and all pixels in pre-and post-earthquake images which span the rupture are typically affected by the ground displacement. This creates complications for image co-registration, alignment and correlation of the final mosaics.</p><p>To address this problem we developed a workflow that automatically generates a DEM (digital elevation model) and an orthorectified image mosaic. The process uses structure-from-motion (SfM) and stereo-matching approaches, and results in precise and accurate registration between the image pairs.</p><p>We applied this method to the 1959 Hebgen Lake earthquake, SW Montana, U.S. This large (Mw 7.2) intraplate normal event re-activated pre-existing faults north of the Hebgen Lake reservoir and created a complex rupture network. We used 20 pre-earthquake photographs from 1947 and 70 post-earthquake images from 1977 and 1982. The final results show a 3-D displacement localized onto several prominent structures: the Hebgen fault and the Red Canyon fault, consistent with field mapping following the earthquake. A significant vertical offset and a large horizontal NS-component agree well with SW extension on NW-SE-striking normal faults. Additionally, we used fault-perpendicular profiles to explore the along-strike variation in fault displacement and to determine the extent of the off-fault damage.</p><p>This work demonstrates that the application of OIC techniques to historical earthquakes can provide new information relating to the geometry and displacement of fault ruptures, and isolate the last event from the previously accumulated displacements. Additionally, the method we propose offers potential for the characterisation of historical earthquakes in general, and promises to improve our understanding of rupture behaviour through a statistical analysis of many earthquakes.</p>

Predicting strains in embedded reinforcement based on surface deformation obtained by digital image correlation technique

2021 ◽  
Author(s):  
Ali Mirzazade ◽  
Cosmin Popescu ◽  
Thomas Blanksvärd ◽  
Björn Täljsten
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Local Strain ◽  
Surface Strain ◽  
Image Correlation ◽  
Correlation Technique ◽  
Proposed Model ◽  
Structural Inspection ◽  
Semi Empirical

<p>This study is carried out to assess the applicability of using a digital image correlation (DIC) system in structural inspection, leading to deploy innovative instruments for strain/stress estimation along embedded rebars. A semi-empirical equation is proposed to predict the strain in embedded rebars as a function of surface strain in RC members. The proposed equation is validated by monitoring the surface strain in ten concrete tensile members, which are instrumented by strain gauges along the internal steel rebar. One advantage with this proposed model is the possibility to predict the local strain along the rebar, unlike previous models that only monitored average strain on the rebar. The results show the feasibility of strain prediction in embedded reinforcement using surface strain obtained by DIC.</p>

scholarly journals A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

2016 ◽  
Vol 23 (3) ◽  
pp. 461-480 ◽  
Author(s):  
Sze-Wei Khoo ◽  
Saravanan Karuppanan ◽  
Ching-Seong Tan
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Measurement ◽  
Surface Deformation ◽  
Optical Measurement ◽  
Image Correlation ◽  
Two Dimensional ◽  
Full Field ◽  
Computation Efficiency ◽  
Dimensional Measurements

Abstract Among the full-field optical measurement methods, the Digital Image Correlation (DIC) is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC) is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

scholarly journals Deformation heterogeneity and texture in surface severe plastic deformation of copper

2016 ◽  
Vol 472 (2187) ◽  
pp. 20150486 ◽  
Author(s):  
Saurabh Basu ◽  
Zhiyu Wang ◽  
Christopher Saldana
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Speed ◽  
Surface Deformation ◽  
Image Correlation ◽  
Surface Mechanical Attrition Treatment ◽  
Model Parameters ◽  
Texture Model ◽  
Mechanical Attrition ◽  
Deformation Mechanics

Comprehensive understanding of thermomechanical response and microstructure evolution during surface severe plastic deformation (S 2 PD) is important towards establishing controllable processing frameworks. In this study, the evolution of crystallographic textures during directional surface mechanical attrition treatment on copper was studied and modelled using the visco-plastic self-consistent framework. In situ high-speed imaging and digital image correlation of surface deformation in circular indentation were employed to elucidate mechanics occurring in a unit process deformation and to calibrate texture model parameters. Material response during directional surface mechanical attrition was simulated using a finite-element model coupled with the calibrated texture model. The crystallographic textures developed during S 2 PD were observed to be similar to those resultant from uniaxial compression. The implications of these results towards facilitating a processing-based framework to predict deformation mechanics and resulting crystallographic texture in S 2 PD configurations are briefly discussed.

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