Postseismic Deformation near the Izmit Earthquake (17 August 1999, M 7.5) Rupture Zone

2002 ◽  
Vol 92 (1) ◽  
pp. 194-207 ◽  
Author(s):  
S. Ergintav
Keyword(s):  
Rupture Zone ◽  
Postseismic Deformation ◽  
Izmit Earthquake

On the cause of enhanced landward motion of the overriding plate after a major subduction earthquake

2020 ◽  
Author(s):  
Mario D'Acquisto ◽  
Matthew Herman ◽  
Rob Govers
Keyword(s):  
Subduction Zones ◽  
Relaxation Times ◽  
Underlying Mechanism ◽  
Rupture Zone ◽  
Elastic Response ◽  
Postseismic Deformation ◽  
Plate Interface ◽  
Mechanical Coupling ◽  
Megathrust Earthquakes ◽  
Viscous Relaxation

<div> <p>During and after a large megathrust earthquake, the overriding plate above the rupture zone moves oceanward. Enigmatically, the post-seismic motion of the overriding plate after several recent large earthquakes, further along strike from the rupture zone, was faster in the landward direction than before the event. Previous studies interpreted these changes as the result of increased mechanical coupling along the megathrust interface, transient slab acceleration, or bulk postseismic deformation with elastic bending mentioned as a possible underlying mechanism. Before invoking additional mechanisms, it is important to understand the contribution of postseismic deformation processes that are inherent features of megathrust earthquakes. We thus aim to quantify and analyse the deformation that produces landward motion during afterslip and viscous relaxation. </p> </div><div> <p>We use velocity-driven 3D mechanical finite element models, in which large megathrust earthquakes occur periodically on the finite plate interface. The model geometry is similar to most present-day subduction zones, but does not exactly match any specific subduction zone. </p> </div><div> <p>The results show increased post-seismic landward motion at (trench-parallel) distances greater than 450 km from the middle of the ruptured asperity. Similar patterns of landward motion are generated by viscous relaxation in the mantle wedge and by deep afterslip on the shear zone downdip of the brittle megathrust interface. Landward displacement due to postseismic relaxation largely accumulates at exponentially decaying rates until ~6 Maxwell relaxation times after the earthquake. The spatial distribution and magnitude of the velocity changes is broadly consistent with observations related to both the 2010 Maule and the 2011 Tohoku-oki earthquakes.  </p> </div><div> <p>Further model experiments show that patterns of landward motion due to afterslip and to viscous relaxation are insensitive to the locking pattern of the megathrust. However, the locking distribution does affect the magnitudes of the displacements and velocities. Results show that the increased landward displacement due to postseismic deformation scales directly proportionally to seismic moment. </p> </div><div> <p>We conclude that the landward motion results from in-plane horizontal bending of the overriding plate and mantle. This bending is an elastic response to oceanward tractions near the base of the plate around the ruptured asperity, causing extension locally and compression further away along-trench. This elastic in-plate bending consistently contributes to earthquake-associated changes in surface velocities for the biggest megathrust earthquakes, producing landward motion along strike from the rupture zone.</p> </div>

Postseismic deformation following the Landers earthquake, California, 28 June 1992

1994 ◽  
Vol 84 (3) ◽  
pp. 780-791 ◽  
Author(s):  
Zheng-Kang Shen ◽  
David D. Jackson ◽  
Yanjie Feng ◽  
Michael Cline ◽  
Mercedes Kim ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Lower Layer ◽  
High Stress ◽  
Rupture Zone ◽  
Postseismic Deformation ◽  
Landers Earthquake ◽  
Initial Rupture ◽  
Global Positioning ◽  
Strain Release ◽  
The Times

Abstract Accelerated strain followed the Landers and Big Bear earthquakes, returning to the normal rate only after a period of several months. We observed this strain throughout most of southern California using the Global Positioning System (GPS). Three GPS receivers operating continuously in fixed positions at Pinyon Flat, Jet Propulsion Laboratory (Pasadena), and Goldstone all recorded postseismic deformation in a relative sense. In addition, we established 16 sites where we deployed portable receivers occasionally over a period of about 6 months near the rupture zones of the earthquakes. Anomalous postseismic displacements ranged from 55 mm near the epicenter to a few millimeters far from the fault. We modeled the displacements, using dislocation theory, as due to variable slip on the faults that were displaced at the times of the earthquakes. The model suggests that the postseismic strain released the equivalent of about 15% of the seismic moment of the mainshock. While the strain released from the upper 10 km is about the same as what can be explained by direct effects of aftershocks, the major contribution of strain release comes from the lower layer, below 10-km depth. Significant afterslip or viscous relaxation must have occurred below 10-km depth to explain the observed deformation more than 100 km from the fault. One interpretation is that high stress on the margin of the co-seismic rupture zone drives the rupture to extend itself into urbroken rock below and along the initial rupture zone.

scholarly journals Resistivity structure in the western part of the fault rupture zone associated with the 1999 İzmit earthquake and its seismogenic implication

2003 ◽  
Vol 55 (7) ◽  
pp. 437-442 ◽  
Author(s):  
S. B. Tank ◽  
Y. Honkura ◽  
Y. Ogawa ◽  
N. Oshiman ◽  
M. K. Tunçer ◽  
...  
Keyword(s):  
Rupture Zone ◽  
Resistivity Structure ◽  
Fault Rupture ◽  
Izmit Earthquake

Spatial variation of aftershock activity across the rupture zone of the 17 August 1999 Izmit earthquake, Turkey

2004 ◽  
Vol 391 (1-4) ◽  
pp. 325-334 ◽  
Author(s):  
M. Aktar ◽  
S. Özalaybey ◽  
M. Ergin ◽  
H. Karabulut ◽  
M.-P. Bouin ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Rupture Zone ◽  
Aftershock Activity ◽  
Izmit Earthquake

scholarly journals Rapid changes in the electrical state of the 1999 Izmit earthquake rupture zone

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Yoshimori Honkura ◽  
Naoto Oshiman ◽  
Masaki Matsushima ◽  
Şerif Barış ◽  
Mustafa Kemal Tunçer ◽  
...  
Keyword(s):  
Rupture Zone ◽  
Earthquake Rupture ◽  
Izmit Earthquake ◽  
Rapid Changes ◽  
Electrical State

Transient Viscosity and Afterslip of the 2015 Mw 8.3 Illapel, Chile, Earthquake

2019 ◽  
Vol 109 (6) ◽  
pp. 2567-2581 ◽  
Author(s):  
Rumeng Guo ◽  
Yong Zheng ◽  
Jianqiao Xu ◽  
Muhammad Shahid Riaz
Keyword(s):  
Stress Relaxation ◽  
Large Earthquake ◽  
Multilayered Structure ◽  
Rupture Zone ◽  
Postseismic Deformation ◽  
Viscoelastic Relaxation ◽  
Combined Model ◽  
Crust And Upper Mantle ◽  
Relaxation Effects ◽  
Viscoelastic Stress Relaxation

Abstract It is usually assumed that short‐term (a few years) postseismic deformation around the rupture zone is caused by continuing slip (afterslip) along the fault interface, and viscoelastic stress relaxation is only responsible for long‐term deformation. In order to verify the validity of this assumption, the initial 1.5 months postseismic displacements following the 2015 Mw 8.3 Illapel earthquake are analyzed based on a multilayered structure model. We explore the possible mechanisms, including afterslip and viscoelastic relaxation, which might have contributed to the postseismic deformation, and aim to distinguish the contributing ratio of different postseismic processes. The results show that either the models of kinematic afterslip or viscoelastic stress relaxation individually cannot match the observed horizontal and vertical postseismic displacements satisfactorily. However, a combined model considering both afterslip and viscoelastic relaxation effects can reduce the data misfit significantly and is more physically reasonable. In the preferred combined model, the transient viscosities of the lower crust and upper mantle are ∼6×1017  Pa s and ∼9×1017  Pa s, respectively. The difference between the afterslip distribution of the pure afterslip model and that of the combined model indicates that previous models based on pure elastic assumption have substantially underestimated the afterslip updip of the rupture zone, and overestimated the afterslip downdip of the rupture zone. Therefore, the role of viscoelastic stress relaxation is indispensable in the study of transient postseismic deformation following a large earthquake, which contradicts the conventional concept about deformation mechanisms of early postseismic process.

scholarly journals Spatiotemporal Evolution of Postseismic Deformation Following the 2001 Mw7.8 Kokoxili, China, Earthquake from 7 Years of Insar Observations

2018 ◽  
Vol 10 (12) ◽  
pp. 1988 ◽  
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Linear Trend ◽  
Near Field ◽  
Surface Displacement ◽  
Rupture Zone ◽  
Postseismic Deformation ◽  
Far Field ◽  
The South ◽  
Large Area ◽  
Envisat Asar ◽  
The North

The 2001 Mw7.8 Kokoxili earthquake, which occurred in the north Tibetan Plateau, ruptured ~400 km of the westernmost portion of the Kunlun fault and produced significant time-dependent postseismic deformation over a large area around the rupture zone and nearby regions. To analyze the postseismic deformation features along different sections of the coseismic surface rupture, we describe the total cumulative postseismic deformation near the center of the rupture and produce velocity maps for the whole observation period and six sub-periods, using InSAR observations (ENVISAT/ASAR, 2003–2010) on five descending tracks. The results indicate that the postseismic deformation is asymmetrically distributed across the fault over a very broad area of ~300 km × 500 km. The south side of the fault exhibits larger displacements and a wider area of deformation that is steadily decaying from near-field to far-field, while the north side displays a narrow, rapidly diminishing deformation field. The maximum cumulative displacement in 2003–2010 reaches up to ~45–60 mm and the LOS peak-to-trough average velocity offset in 2003–2010 reaches ~13–16 mm/yr at ~92.5°E. The short-term postseismic velocity estimates in the six sub-periods reflect significant spatial variation and temporal differences on different sections. Motions to the south of the two ends of the rupture zone show more rapid velocity decay compared to near the main central rupture zone. The time- and distance-dependent timeseries of postseismic surface displacement reveal exponential decay in the near-field and a nearly linear trend in the far-field of the fault.

scholarly journals Spatial variation of the stress field along the fault rupture zone of the 1999 Izmit earthquake

2010 ◽  
Vol 62 (3) ◽  
pp. 237-256 ◽  
Author(s):  
A. Pınar ◽  
S.B. Üçer ◽  
Y. Honkura ◽  
N. Sezgin ◽  
A. Ito ◽  
...  
Keyword(s):  
Stress Field ◽  
Spatial Variation ◽  
Rupture Zone ◽  
Fault Rupture ◽  
Izmit Earthquake
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