scholarly journals Geometric Variation in the Surface Rupture of the 2018 Mw7.5 Palu Earthquake from Subpixel Optical Image Correlation

2020 ◽  
Vol 12 (20) ◽  
pp. 3436
Author(s):  
Chenglong Li ◽  
Guohong Zhang ◽  
Xinjian Shan ◽  
Dezheng Zhao ◽  
Xiaogang Song
Keyword(s):  
Shear Strain ◽  
Surface Deformation ◽  
Horizontal Displacement ◽  
Strike Slip ◽  
Image Correlation ◽  
Displacement Fields ◽  
Surface Rupture ◽  
The North ◽  
Deformation Patterns ◽  
Geometric Variation

We obtained high-resolution (10 m) horizontal displacement fields from pre- and post-seismic Sentinel-2 optical images of the 2018 Mw7.5 Palu earthquake using subpixel image correlation. From these, we calculated the curl, divergence, and shear strain fields from the north-south (NS) and east-west (EW) displacement fields. Our results show that the surface rupture produced by the event was distributed within the Sulawesi neck (0.0974–0.6632°S) and Palu basin (0.8835–1.4206°S), and had a variable strike of 313.0–355.2° and strike slip of 2.00–6.62 m. The NS and EW displacement fields within the Palu basin included fine-scale displacements in both the near- and far-fault, the deformation patterns included a small restraining bend (localized shortening), a distributed rupture zone, and a major releasing bend (net extension) from the curl, divergence, and shear strain. Surface rupture was dominated by left-lateral strike-slip from initiation to termination, with a localized normal slip component peaking at ~3.75 m. The characteristics and geometric variation of the ruptured fault controlled both the formation of these surface deformation patterns and sustained supershear rupture.

scholarly journals Experimental Investigation on Fracture Evolution in Sandstone Containing an Intersecting Hole under Compression Using DIC Technique

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Hao Wu ◽  
Guoyan Zhao ◽  
Weizhang Liang ◽  
Enjie Wang ◽  
Shaowei Ma
Keyword(s):  
Fracture Behavior ◽  
Horizontal Displacement ◽  
Image Correlation ◽  
Propagation Mechanism ◽  
Shear Cracks ◽  
Compression Tests ◽  
Displacement Fields ◽  
Red Sandstone ◽  
Tensile Cracks ◽  
Dic Technique

Failure of underground structures, especially intersections, becomes more severe as the depth increases, which poses a new challenge for the safe construction and operation of deep rock engineering. To investigate the mechanical properties and fracture behavior of rock with an intersecting hole under compressive loads, a series of uniaxial compression tests was carried out on cuboid red sandstone specimens containing an intersecting hole with three types of shapes by digital image correlation (DIC) technique. The results showed that the existing hole inside specimens leads to almost a 50% reduction of mechanical parameters from that of intact ones, and this weakening effect is associated with the shapes of holes. Failure of specimens is a progressive process in which cracks, i.e., primary tensile cracks, secondary tensile cracks, and shear cracks, initiate from stress concentration zones, propagate along certain direction, and coalesce with each other into macrofractures. Both the real-time principal strain fields and horizontal displacement fields of specimens under compression could be visually displayed by DIC system, and they were in good consistency in characterizing the fracture behavior. Moreover, the propagation characteristics of primary tensile cracks were studied further by quantitatively analyzing the strain variation during the loading process, and the propagation mechanism of “open-close-reopen” of primary tensile cracks was explained in detail.

Rapid Geodetic Observations of Spatiotemporally Varying Postseismic Deformation Following the Ridgecrest Earthquake Sequence: The U.S. Geological Survey Response

2020 ◽  
Vol 91 (4) ◽  
pp. 2108-2123 ◽  
Author(s):  
Benjamin A. Brooks ◽  
Jessica Murray ◽  
Jerry Svarc ◽  
Eleyne Phillips ◽  
Ryan Turner ◽  
...  
Keyword(s):  
Time Series ◽  
Horizontal Displacement ◽  
The United States ◽  
Satellite System ◽  
Earthquake Sequence ◽  
Postseismic Deformation ◽  
Displacement Fields ◽  
Surface Rupture ◽  
Global Navigation Satellite ◽  
The U.S

Abstract The U.S. Geological Survey’s geodetic response to the 4–5 July 2019 (Pacific time) Ridgecrest earthquake sequence comprised primarily the installation and/or reoccupation of Global Navigation Satellite System (GNSS) monumentation. Our response focused primarily on the United States’ Navy’s China Lake Naval Air Weapons Station base (NAWSCL). This focus was because much of the surface rupture occurred on the NAWSCL and because of NAWSCL access restrictions only permitting Federal and State of California personnel. In total, we measured or are still measuring at 24 sites, 14 of which were on the NAWSCL and, as of this writing, operational. The majority of sites were set up as continuous stations logging at either 1 sample per second or 1 sample per 15 s. Two stations were recording a 200 m cross-rupture aperture starting ∼10  hr after the M 6.4 event, and they recorded the coseismic displacements of the M 7.1. Approximately, 1 hr after the M 7.1 event, two new stations were recording a ∼200  m cross-rupture aperture of the surface rupture. In the days following, we established the rest of the stations ranging to a distance of ∼15  km from the M 7.1 principal rupture trace. The lack of differential displacement across the M 6.4 rupture during the M 7.1 event suggests that it did not reactivate the M 6.4 plane. The lack of differential cross-fault displacement for both events suggests that rapid shallow afterslip did not occur at those two locations. The postseismic time series from these stations shows centimeters of horizontal displacement over periods of a few months. They record a mixture of fault-parallel and fault-normal displacements that, in conjunction with analysis of more spatially complete Interferometric Synthetic Aperture Radar displacement fields, suggest that both poroelastic and afterslip phenomena occur along the M 6.4 and 7.1 rupture planes. Using preliminary data from these and other regional stations, we also explore the Ridgecrest sequence’s effect on regional GNSS time series and the differentiation of long-term postseismic motions and secular deformation rates. We find that redefining a common-mode noise filter using different GNSS stations that are assumed to be unaffected by the earthquakes results in small but systematic differences in the regional velocity field estimate.

scholarly journals The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking Australian stable continental region earthquakes

2019 ◽  
Author(s):  
Dan J. Clark ◽  
Sarah Brennand ◽  
Gregory Brenn ◽  
Trevor I. Allen ◽  
Matthew C. Garthwaite ◽  
...  
Keyword(s):  
Western Australia ◽  
Surface Deformation ◽  
Vertical Displacement ◽  
Strike Slip ◽  
Double Difference ◽  
Surface Rupture ◽  
Field Mapping ◽  
Scaling Relationships ◽  
Magnitude Scaling ◽  
Stable Continental Region

Abstract. Modern geodetic and seismic monitoring tools are enabling the study of moderate-sized earthquake sequences in unprecedented detail. Here we use a variety of methods to examine surface deformation caused by a sequence of earthquakes near Lake Muir in southwest Western Australia in 2018. A shallow MW 5.3 earthquake on the 16th of September 2018 was followed on the 8th of November 2018 by a MW 5.2 event in the same region. Focal mechanisms for the events suggest reverse and strike-slip rupture, respectively. Interferometric Synthetic Aperture Radar (InSAR) analysis of the events suggests that the ruptures are in part spatially coincident. Field mapping, guided by the InSAR results, reveals that the first event produced an approximately 3 km long and up to 0.5 m high west-facing surface rupture, consistent with slip on a moderately east-dipping fault. Double difference hypocentre relocation of aftershocks using data from rapidly deployed seismic instrumentation confirms an east-dipping rupture plane for the first event, and shows a concentration located at the northern end of the rupture where the InSAR suggests greatest vertical displacement. The November event resulted from rupture on a northeast-trending strike-slip fault. UAV-derived digital terrain models (differenced with pre-event LiDAR) reveal a surface deformation envelope consistent with the InSAR for the first event, but could not discern deformation unique to the second event. New rupture length versus magnitude scaling relationships developed for non-extended cratonic regions as part of this study allow for the distinction between “visible” surface rupture lengths (VSRL) from field-mapping and “detectable” surface rupture lengths (DSRL) from remote sensing techniques such as InSAR, and suggest longer ruptures for a given magnitude than implied by commonly used scaling relationships.

scholarly journals Multi-phase tectonic structures in the collision zone of the Kolyma-Omolon microcontinent and the eastern margin of the North Asian craton, Northeastern Russia

2009 ◽  
Vol 4 ◽  
pp. 65-70 ◽  
Author(s):  
A. V. Prokopiev ◽  
V. S. Oxman
Keyword(s):  
Horizontal Displacement ◽  
Strike Slip ◽  
Northeastern Russia ◽  
Second Phase ◽  
Tectonic Structures ◽  
North Asian Craton ◽  
Eastern Margin ◽  
The North ◽  
Two Phases ◽  
Multi Phase

Abstract. The sequence of formation of structures is established in the zone of junction of the eastern margin of the North Asian craton and the northeastern flank of the Kolyma-Omolon microcontinent, in the area of bend of the Kolyma structural loop. Detailed structural studies revealed two phases in the formation of Mesozoic structures – an early thrust phase and a late strike-slip phase. Structures formed during each of the phases are described. Thrust structures are represented by the Setakchan nappe on which the minimum amount of horizontal displacement is estimated at 13–15 km. Later superposed left-lateral strike-slip faults have a north strike. Formation of these latter structures occurred during the second phase of collision between the Kolyma-Omolon microcontinent and the eastern margin of the North Asian craton.

Using Daily Observations from Planet Labs Satellite Imagery to Separate the Surface Deformation between the 4 July Mw 6.4 Foreshock and 5 July Mw 7.1 Mainshock during the 2019 Ridgecrest Earthquake Sequence

2020 ◽  
Vol 91 (4) ◽  
pp. 1986-1997 ◽  
Author(s):  
Chris Milliner ◽  
Andrea Donnellan
Keyword(s):  
Satellite Imagery ◽  
Surface Deformation ◽  
Image Correlation ◽  
Earthquake Sequence ◽  
Interferometric Synthetic Aperture Radar ◽  
The North ◽  
Stress Changes ◽  
Surface Ruptures ◽  
Pixel Value ◽  
Optical Imagery

Abstract On 4 July 2019, the Ridgecrest earthquake sequence began with a series of foreshocks including an Mw 6.4 event near Searles Valley, California. This was then followed 34 hr later by an Mw 7.1 mainshock located just 15 km to the north, with the earthquake sequence resulting in a complex array of intersecting faults. This earthquake sequence poses several interesting questions including, did the stress changes induced by the Mw 6.4 foreshock trigger the Mw 7.1 mainshock and what possible mechanism(s) could explain the occurrence of widespread secondary faulting surrounding both surface ruptures? However, most of the geodetic data (such as Interferometric Synthetic Aperture Radar, light detection and ranging, and optical satellite imagery) were acquired after both events had occurred making it difficult to discern which surface fractures happened when and their possible triggering mechanism. Here, we provide a dataset composed of high-resolution optical imagery, pixel-value difference maps, .kmz fracturing mapping, and horizontal deformation maps derived from subpixel image correlation, which can uniquely separate the surface fracturing and deformation between the foreshock and mainshock events that can help answer these questions. Separate imaging of the events is made possible by the daily acquisition of optical imagery by the Planet Labs cubesat constellation, which acquired data between the two earthquakes, in the morning of 4 and 5 July, at 11.13 a.m. and 05.12 p.m. PST, respectively, with the images acquired just 40 min after the foreshock and 56 min before the mainshock, respectively. Analysis from this optical imagery reveals the location of surface faulting that allows us to map their spatial extent and determine their timing. These data which we provide here can help guide and validate field survey observations to help understand which faults ruptured when, and constrain slip inversion models for more accurate estimates of stress changes induced by the foreshock imposed on the surrounding faults.

scholarly journals Experimental Study on the Fracture Process Zone Characteristics in Concrete Utilizing DIC and AE Methods

2019 ◽  
Vol 9 (7) ◽  
pp. 1346 ◽  
Author(s):  
Shuhong Dai ◽  
Xiaoli Liu ◽  
Kumar Nawnit
Keyword(s):  
Crack Extension ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Surface Deformation ◽  
Process Zone ◽  
Image Correlation ◽  
Displacement Fields ◽  
Ae Signal ◽  
Tip Position ◽  
Extension Length

The present work focuses on investigating the characteristics of the fracture process zone (FPZ) in concrete. The Single-edge notched (SEN) concrete beams under three-points bending are employed for conducting mode I fracture propagation. The displacement fields on the specimen surface and the internal AE signal of specimen are obtained simultaneously in real time by digital image correlation (DIC) and acoustic emission (AE) techniques. The experimental and analytical results indicated that the crack tip position, the crack extension length and the stress intensity factors (SIF) are obtained dynamically and quantitatively by DIC technique, and the length of FPZ is identified, respectively, by DIC and AE techniques in the crack extension process. The distribution of internal AE events is consistent with that of FPZ identified from surface deformation of specimens.

SIMULATION OF SURFACE DEFORMATION USING INCONEL 718 DIC-ANALYSIS OF HEATING ALLOY

2021 ◽  
pp. 306-311
Author(s):  
Sergey Adjamskiy ◽  
Ganna Kononenko ◽  
Rostislav Podolskyi
Keyword(s):  
Mechanical Properties ◽  
Inconel 718 ◽  
Surface Deformation ◽  
Structural Strength ◽  
Correlation Method ◽  
Local Deformation ◽  
Image Correlation ◽  
Displacement Fields ◽  
Degree Of Deformation ◽  
Three Samples

. Fracture is the final stage of metal behavior under load, and the resistance that themetal gives to the development of this process, largely determines its structural strength. Inconel718 is gaining strength mainly due to the dispersion hardening in the allocation of secondaryphases. Purpose: to establish a set of mechanical properties and microstructure of heatstrengthened Inconel 718 and to investigate changes in the degree of deformation of the surfacemetal by the method of registration of macroloca l fields. Mechanical properties were determinedby standard methods on three samples. Registration of macrolocal displacement fields wasrecorded by DIC (digital image correlation) method simultaneously with stretching. The dataobtained from the DIC analy sis showed that at the time of rupture the local deformation of thesample increased to 36% sample 1, up to 50% sample 2, up to 25% sample 3. It is shown thatthe microstructure of the studied samples is homogeneous, the detected grain γ structure with theformation of duplicates, the density of the experimental samples was 98.3%.

scholarly journals Rupture Kinematics and Coseismic Slip Model of the 2021 Mw 7.3 Maduo (China) Earthquake: Implications for the Seismic Hazard of the Kunlun Fault

2021 ◽  
Vol 13 (16) ◽  
pp. 3327
Author(s):  
Han Chen ◽  
Chunyan Qu ◽  
Dezheng Zhao ◽  
Chao Ma ◽  
Xinjian Shan
Keyword(s):  
Three Dimensional ◽  
Surface Displacement ◽  
Horizontal Displacement ◽  
Descent Method ◽  
Steepest Descent Method ◽  
Coseismic Deformation ◽  
Slip Model ◽  
Displacement Fields ◽  
Coseismic Slip ◽  
The North

The 21 May 2021 Maduo earthquake was the largest event to occur on a secondary fault in the interior of the active Bayanhar block on the north-central Tibetan plateau in the last twenty years. A detailed kinematic study of the Maduo earthquake helps us to better understand the seismogenic environments of the secondary faults within the block, and its relationship with the block-bounding faults. In this study, firstly, SAR images are used to obtain the coseismic deformation fields. Secondly, we use a strain model-based method and steepest descent method (SDM) to resolve the three-dimensional displacement components and to invert the coseismic slip distribution constrained by coseismic displacement fields, respectively. The three-dimensional displacement fields reveal a dominant left-lateral strike-slip motion, local horizontal displacement variations and widely distributed near-fault subsidence/uplift deformation. We prefer a five-segment fault slip model, with well constrained fault geometry featuring different dip angles and striking, constrained by InSAR observations. The peak coseismic slip is estimated to be ~5 m near longitude 98.9°E at a depth of ~4–7 km. Overall, the distribution of the coseismic slip on the fault is highly correlated to the measured surface displacement offsets along the entire rupture. We observe the moderate shallow slip deficit and limited afterslip deformation following the Maduo earthquake, it may indicate the effects of off-fault deformation during the earthquake and stable interseismic creep on the fault. The occurrence of the Maduo earthquake on a subsidiary fault updates the importance and the traditional estimate of the seismic hazards for the Kunlun fault.

scholarly journals Performance Evaluation of Different SAR-Based Techniques on the 2019 Ridgecrest Sequence

2021 ◽  
Vol 13 (4) ◽  
pp. 685
Author(s):  
Marco Polcari ◽  
Mimmo Palano ◽  
Marco Moro
Keyword(s):  
Performance Evaluation ◽  
Strike Slip ◽  
Seismic Sequence ◽  
Fault Rupture ◽  
Coseismic Displacement ◽  
Surface Rupture ◽  
Eastern California Shear Zone ◽  
Tectonic Framework ◽  
Gnss Network ◽  
The One

We evaluated the performances of different SAR-based techniques by analyzing the surface coseismic displacement related to the 2019 Ridgecrest seismic sequence (an Mw 6.4 foreshock on July 4th and an Mw 7.1 mainshock on July 6th) in the tectonic framework of the eastern California shear zone (Southern California, USA). To this end, we compared and validated the retrieved SAR-based coseismic displacement with the one estimated by a dense GNSS network, extensively covering the study area. All the SAR-based techniques constrained the surface fault rupture well; however, in comparison with the GNSS-based coseismic displacement, some significant differences were observed. InSAR data showed better performance than MAI and POT data by factors of about two and three, respectively, therefore confirming that InSAR is the most consolidated technique to map surface coseismic displacements. However, MAI and POT data made it possible to better constrain the azimuth displacement and to retrieve the surface rupture trace. Therefore, for cases of strike-slip earthquakes, all the techniques should be exploited to achieve a full synoptic view of the coseismic displacement field.

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