scholarly journals Stress Changes on the Garlock Fault during and after the 2019 Ridgecrest Earthquake Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1752-1764 ◽  
Author(s):  
Marlon D. Ramos ◽  
Jing Ci Neo ◽  
Prithvi Thakur ◽  
Yihe Huang ◽  
Shengji Wei
Keyword(s):  
Near Field ◽  
Earthquake Swarm ◽  
Local Stress ◽  
Stress Change ◽  
Earthquake Sequence ◽  
Dynamic Rupture ◽  
Eastern California Shear Zone ◽  
Stress Changes ◽  
Garlock Fault ◽  
Insight Into

ABSTRACT The recent 2019 Ridgecrest earthquake sequence in southern California jostled the seismological community by revealing a complex and cascading foreshock series that culminated in a Mw 7.1 mainshock. But the central Garlock fault, despite being located immediately south of this sequence, did not coseismically fail. Instead, the Garlock fault underwent postseismic creep and exhibited a sizeable earthquake swarm. The dynamic details of the rupture process during the mainshock are largely unknown, as is the amount of stress needed to bring the Garlock fault to failure. We present an integrated view of how stresses changed on the Garlock fault during and after the mainshock using a combination of tools including kinematic slip inversion, Coulomb stress change (ΔCFS), and dynamic rupture modeling. We show that positive ΔCFSs cannot easily explain observed aftershock patterns on the Garlock fault but are consistent with where creep was documented on the central Garlock fault section. Our dynamic model is able to reproduce the main slip asperities and kinematically estimated rupture speeds (≤2  km/s) during the mainshock, and suggests the temporal changes in normal and shear stress on the Garlock fault were the greatest near the end of rupture. The largest static and dynamic stress changes on the Garlock fault we observe from our models coincide with the creeping region, suggesting that positive stress perturbations could have caused this during or after the mainshock rupture. This analysis of near-field stress-change evolution gives insight into how the Ridgecrest sequence influenced the local stress field of the northernmost eastern California shear zone.

Rupture Process of the 2019 Ridgecrest, California Mw 6.4 Foreshock and Mw 7.1 Earthquake Constrained by Seismic and Geodetic Data

2020 ◽  
Vol 110 (4) ◽  
pp. 1603-1626 ◽  
Author(s):  
Kang Wang ◽  
Douglas S. Dreger ◽  
Elisa Tinti ◽  
Roland Bürgmann ◽  
Taka’aki Taira
Keyword(s):  
Seismic Data ◽  
Seismic Event ◽  
Rupture Process ◽  
Earthquake Sequence ◽  
Depth Range ◽  
Coseismic Slip ◽  
Eastern California Shear Zone ◽  
Garlock Fault ◽  
The One ◽  
Good Coverage

ABSTRACT The 2019 Ridgecrest earthquake sequence culminated in the largest seismic event in California since the 1999 Mw 7.1 Hector Mine earthquake. Here, we combine geodetic and seismic data to study the rupture process of both the 4 July Mw 6.4 foreshock and the 6 July Mw 7.1 mainshock. The results show that the Mw 6.4 foreshock rupture started on a northwest-striking right-lateral fault, and then continued on a southwest-striking fault with mainly left-lateral slip. Although most moment release during the Mw 6.4 foreshock was along the southwest-striking fault, slip on the northwest-striking fault seems to have played a more important role in triggering the Mw 7.1 mainshock that happened ∼34  hr later. Rupture of the Mw 7.1 mainshock was characterized by dominantly right-lateral slip on a series of overall northwest-striking fault strands, including the one that had already been activated during the nucleation of the Mw 6.4 foreshock. The maximum slip of the 2019 Ridgecrest earthquake was ∼5  m, located at a depth range of 3–8 km near the Mw 7.1 epicenter, corresponding to a shallow slip deficit of ∼20%–30%. Both the foreshock and mainshock had a relatively low-rupture velocity of ∼2  km/s, which is possibly related to the geometric complexity and immaturity of the eastern California shear zone faults. The 2019 Ridgecrest earthquake produced significant stress perturbations on nearby fault networks, especially along the Garlock fault segment immediately southwest of the 2019 Ridgecrest rupture, in which the coulomb stress increase was up to ∼0.5  MPa. Despite the good coverage of both geodetic and seismic observations, published coseismic slip models of the 2019 Ridgecrest earthquake sequence show large variations, which highlight the uncertainty of routinely performed earthquake rupture inversions and their interpretation for underlying rupture processes.

The impact of the 2019 Ridgecrest earthquake sequence on time-dependent earthquake probabilities for the Garlock fault, California, USA

2020 ◽  
Author(s):  
Sara Carena ◽  
Alessandro Verdecchia ◽  
Alessandro Valentini ◽  
Bruno Pace
Keyword(s):  
Temporal Distribution ◽  
Passage Time ◽  
Earthquake Sequence ◽  
Recurrence Time ◽  
Owens Valley ◽  
Probability Of Occurrence ◽  
Central Segment ◽  
Stress Changes ◽  
Garlock Fault ◽  
The Impact

<p>The 2019 M 6.4 Searles Valley and the M 7.1 Ridgecrest earthquakes occurred in the Eastern California Shear Zone (ECSZ) between the southern tip of the Owens Valley fault and the central segment of the Garlock fault. This earthquake sequence, as shown by recent studies based on cumulative (coseismic plus postseismic) Coulomb stress (ΔCFS) modeling, is likely to have been influenced by previous earthquakes in the ECSZ, reinforcing the hypothesis that the spatial and temporal distribution of major earthquakes in this region is controlled by the location and timing of past events. In turn, the 2019 Ridgecrest sequence has likely reshaped the state of stress on neighbouring faults, and as a consequence modified the probability of occurrence of future events in the region.</p><p>Here, focusing on the Garlock fault, we calculate the cumulative ΔCFS due to several major (M ≥ 7) earthquakes which occurred in the ECSZ and surrounding areas (e.g. San Andreas fault) following the most recent event on the Garlock fault (A.D. 1450-1640), and up to and including the Ridgecrest sequence. We then use these results to evaluate the influence of stress changes due to past earthquakes on a probabilistic seismic hazard model for the Garlock fault.</p><p>In our first probabilistic model, we calculate BPT (Brownian Passage Time) curves of occurrence of a M ≥ 7 event on the central segment of the Garlock fault in the next 30 years, using recurrence time and coefficient of variation values calculated from paeloseismological data. Preliminary results show a probability of occurrence in 30 years of up to 10% when we do not consider the effect of ΔCFS. This increases to about 15% when ΔCFS effects are introduced in the model.</p><p>As a next step, we will implement a more complex segmented model for the Garlock fault, where probability calculations take into account multiple possible rupture combinations.</p>

scholarly journals Dynamic Rupture Modeling to Investigate the Role of Fault Geometry in Jumping Rupture Between Parallel‐Trace Thrust Faults

2019 ◽  
Vol 109 (6) ◽  
pp. 2168-2186 ◽  
Author(s):  
Paul Peshette ◽  
Julian Lozos ◽  
Doug Yule ◽  
Eileen Evans
Keyword(s):  
Near Field ◽  
Stress Conditions ◽  
Parameter Study ◽  
Thrust Faults ◽  
Dynamic Rupture ◽  
Long Distance ◽  
Fault Strength ◽  
Stress Changes ◽  
Dip Angle ◽  
3D Finite Element Method

Abstract Investigations of historic surface‐rupturing thrust earthquakes suggest that rupture can jump from one fault to another up to 8 km away. Additionally, there are observations of jumping rupture between thrust faults ∼50  km apart. In contrast, previous modeling studies of thrust faults find a maximum jumping rupture distance of merely 0.2 km. Here, we present a dynamic rupture modeling parameter study that attempts to reconcile these differences and determines geometric and stress conditions that promote jumping rupture. We use the 3D finite‐element method to model rupture on pairs of thrust faults with parallel surface traces and opposite dip orientations. We vary stress drop and fault strength ratio to determine conditions that produce jumping rupture at different dip angles and different minimum distance between faults. We find that geometry plays an essential role in determining whether or not rupture will jump to a neighboring thrust fault. Rupture is more likely to jump between faults dipping toward one another at steeper angles, and the behavior tapers down to no rupture jump in shallow dip cases. Our variations of stress parameters emphasize these toward‐orientation results. Rupture jump in faults dipping away from one another is complicated by variations of stress conditions, but the most prominent consistency is that for mid‐dip angle faults rupture rarely jumps. If initial stress conditions are such that they are already close to failure, the possibility of a long‐distance jump increases. Our models call attention to specific geometric and stress conditions where the dynamic rupture front is the most important to potential for jumping rupture. However, our models also highlight the importance of near‐field stress changes due to slip. According to our modeling, the potential for rupture to jump is strongly dependent on both dip angle and orientation of faults.

scholarly journals A possible stress interaction between large thrust and normal faulting earthquakes in the Mexican subduction zone

1999 ◽  
Vol 89 (6) ◽  
pp. 1418-1427 ◽  
Author(s):  
Takeshi Mikumo ◽  
Shri Krishna Singh ◽  
Miguel A. Santoyo
Keyword(s):  
High Stress ◽  
Stress Change ◽  
Vertical Shear ◽  
3D Analysis ◽  
Normal Faulting ◽  
Dynamic Rupture ◽  
Cocos Plate ◽  
Stress Changes ◽  
Subducting Plate ◽  
Mexico Earthquake

Abstract A large, nearly vertical, normal-faulting earthquake (Mw = 7.1) took place in 1997 in the subducting Cocos plate just beneath the ruptured fault zone of the 1985 Michoacan, Mexico, earthquake (Mw = 8.1). We investigate the possibility of stress interaction between the two large events through a 3D analysis of coseismic-stress change that was due to the first event, taking into consideration the postseismic change and the dynamic rupture process of the second event. In the middle portion of the subducting plate at depths below 30 km, the calculated coseismic increase in the vertical-shear stress and in the Coulomb-failure stress beneath the high stress-drop zones of the 1985 earthquake is in the order of 0.4 to 0.8 MPa. It was also found that the 1997 earthquake took place in the zone of maximum coseismic-stress increase. Possible postseismic-stress changes due to the subduction process or to the loading of the overriding continental lithosphere and from aseismic slip would enhance the coseismic-stress change and hence the possibility of occurrence of a normal-faulting earthquake in the subducting plate. The dynamic rupture pattern of the 1997 event seems to be consistent with the inferred stress interactions.

scholarly journals Stress Changes on the Garlock fault during and after the 2019 Ridgecrest Earthquake Sequence

2020 ◽  
Author(s):  
Marlon Ramos ◽  
Jing Ci Neo ◽  
Prithvi Thakur ◽  
Yihe Huang ◽  
Shengji Wei
Keyword(s):  
Earthquake Sequence ◽  
Stress Changes ◽  
Garlock Fault

scholarly journals Infrared vibrational nanocrystallography and nanoimaging

2016 ◽  
Vol 2 (10) ◽  
pp. e1601006 ◽  
Author(s):  
Eric A. Muller ◽  
Benjamin Pollard ◽  
Hans A. Bechtel ◽  
Peter van Blerkom ◽  
Markus B. Raschke
Keyword(s):  
Ion Mobility ◽  
Molecular Orientation ◽  
Hybrid Imaging ◽  
Defect Formation ◽  
Near Field ◽  
Molecular Solids ◽  
Optical Antenna ◽  
Molecular Bond ◽  
Low Symmetry ◽  
Insight Into

Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids.

Internal Stress Change of Phosphorus-Doped Amorphous Silicon Thin Films During Crystallization

1994 ◽  
Vol 343 ◽  
Author(s):  
Hideo Miura ◽  
Asao Nishimura
Keyword(s):  
Thin Films ◽  
Tensile Stress ◽  
Internal Stress ◽  
Crystallization Process ◽  
Chemical Vapor ◽  
Stress Change ◽  
Silicon Thin Films ◽  
Stress Changes ◽  
Phosphorus Doped ◽  
Deposited Films

ABSTRACTInternal stress change of phosphorus-doped silicon thin films during crystallization is measured by detecting substrate curvature change using a scanning laser microscope. The films are deposited in an amorphous phase by chemical vapor deposition using Si2H6 gas. The deposited films have compressive stress of about 200 MPa. The internal stress changes significantly to a tensile stress of about 800 MPa at about 600 °C due to shrinkage of the films during crystallization. The high tensile stress can be relaxed by annealing above 800 °C. The phosphorus doping changes the crystallization process of the films and their final residual stress.

Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan

2020 ◽  
Vol 224 (1) ◽  
pp. 416-434
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Main Shock ◽  
Near Field ◽  
Active Faults ◽  
Fault Model ◽  
Body Waves ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Seismic Displacement ◽  
Stress Changes

SUMMARY We investigate the coseismic and post-seismic deformation due to the 6 February 2018 Mw 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults.

scholarly journals Rupture-dependent breakdown energy in fault models with thermo-hydro-mechanical processes

2020 ◽  
Author(s):  
Valère Lambert ◽  
Nadia Lapusta
Keyword(s):  
Material Property ◽  
Numerical Models ◽  
Slip Rate ◽  
Shear Cracks ◽  
Dynamic Rupture ◽  
Rupture Dynamics ◽  
Stress Changes ◽  
History Of ◽  
Thermal Pressurization ◽  
Pass Through

Abstract. Substantial insight into earthquake source processes has resulted from considering frictional ruptures analogous to cohesive-zone shear cracks from fracture mechanics. This analogy holds for slip-weakening representations of fault friction that encapsulate the resistance to rupture propagation in the form of breakdown energy, analogous to fracture energy, prescribed in advance as if it were a material property of the fault interface. Here, we use numerical models of earthquake sequences with enhanced weakening due to thermal pressurization of pore fluids to show how accounting for thermo-hydro-mechanical processes during dynamic shear ruptures makes breakdown energy rupture-dependent. We find that local breakdown energy is neither a constant material property nor uniquely defined by the amount of slip attained during rupture, but depends on how that slip is achieved through the history of slip rate and dynamic stress changes during the rupture process. As a consequence, the frictional breakdown energy of the same location along the fault can vary significantly in different earthquake ruptures that pass through. These results suggest the need for re-examining the assumption of pre-determined frictional breakdown energy common in dynamic rupture modeling and for better understanding of the factors that control rupture dynamics in the presence of thermo-hydro-mechanical processes.

The earthquake sequence in Friuli, Italy, 1976

1979 ◽  
Vol 69 (6) ◽  
pp. 1797-1818
Author(s):  
Vittorio Cagnetti ◽  
Vincenzo Pasquale
Keyword(s):  
Main Shock ◽  
Eastern Alps ◽  
Earthquake Sequence ◽  
Laboratory Studies ◽  
Fault Movement ◽  
Stress Changes ◽  
Entire Sequence ◽  
Strain Release ◽  
Largest Aftershock ◽  
Aftershock Region

abstract The seismic activity of the May 6, 1976 Friuli earthquake has been investigated. It provides clear evidence of internal clustering of shocks, with the largest aftershocks being followed by their own series of aftershocks. Late large aftershocks with their own aftershock series occurred 4 months after the main shock, when aftershocks had subsided. Thus, in the entire series of aftershocks, six phases of strain release are found, and part of the aftershock region is not included in the aftershock volume of the main shock. All this indicates that a few aftershocks are at least partially independent from the main shock. The value of b is estimated for the entire sequence and for the separate phases; during the activity, b shows an increase after the main shock, a decline immediately before the largest aftershock, and a second increase immediately afterward. This can be explained in terms of stress changes, and is consistent with laboratory studies of rock deformation. The compressive stress is perpendicular to the Eastern Alps, and may be considered as the principal cause of the earthquake sequence. The solution of the main shock of the sequence is a reversed fault movement, unlike most of the mechanisms in the focus of the earlier Friuli earthquakes which are of the transcurrent type.

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