Implications of the earthquake cycle for inferring fault locking on the Cascadia megathrust

2017 ◽  
pp. ggx009
Author(s):  
F. F. Pollitz ◽  
E. L. Evans
Author(s):  
Faqi Diao ◽  
Rongjiang Wang ◽  
Yage Zhu ◽  
Xiong Xiong

Abstract Based on a viscoelastic earthquake-cycle deformation model, we revisit the fault locking of the central Himalayan thrust using geodetic data acquired in the past three decades. By incorporating the viscoelastic relaxation effect induced by stress buildup and release, our viscoelastic model is capable of explaining the far-field observation with similar fault locking width obtained in previous studies. Elastic models underestimate the far-field deformation and consequently underestimate the fault slip rate by attributing the far-field deformation to stable intraplate deformation. A steady-state viscosity of ∼1019  Pa·s is required for the lower crust beneath south Tibet to best fit the crustal velocity. The optimal slip rate and locking width of the central Main Himalayan Thrust are estimated to 18.8 ± 1.6 mm/a and 85 ± 2.1 km, respectively. The inferred fault locking width, along with the down-dip rupture extension of the 2015 Gorkha earthquake, agrees well with the identified mid-crustal ramp, which leads to an interpretation that the fault geometry of the central Himalayan thrust plays an important role on fault kinematics. Our results highlight that viscoelastic relaxation during the earthquake cycle should be incorporated for robust estimation of fault locking parameters and reasonable data fitting.


2002 ◽  
Vol 54 (11) ◽  
pp. 1139-1146 ◽  
Author(s):  
Jean-Pierre Gratier ◽  
Pascal Favreau ◽  
François Renard ◽  
Eric Pili

2013 ◽  
Vol 609 ◽  
pp. 504-523 ◽  
Author(s):  
Tim J. Wright ◽  
John R. Elliott ◽  
Hua Wang ◽  
Isabelle Ryder

2021 ◽  
Author(s):  
David T. Sandwell

David Sandwell developed this advanced textbook over a period of nearly 30 years for his graduate course at Scripps Institution of Oceanography. The book augments the classic textbook Geodynamics by Don Turcotte and Jerry Schubert, presenting more complex and foundational mathematical methods and approaches to geodynamics. The main new tool developed in the book is the multi-dimensional Fourier transform for solving linear partial differential equations. The book comprises nineteen chapters, including: the latest global data sets; quantitative plate tectonics; plate driving forces associated with lithospheric heat transfer and subduction; the physics of the earthquake cycle; postglacial rebound; and six chapters on gravity field development and interpretation. Each chapter has a set of student exercises that make use of the higher-level mathematical and numerical methods developed in the book. Solutions to the exercises are available online for course instructors, on request.


1996 ◽  
Vol 39 (3) ◽  
Author(s):  
S. C. Stiros

Coastal challenges ill West Crete ill the last 4000 years can be described as a series of 11 relatively small (25 cm on the average) land subsidences alternating with short (150-250 year long) relatively still stands of the sea level. At 1500 B.P. an up to 9 m episodic relative land uplift and tilting of this part of the island occurred, but since then no significant coastal changes have been identified. There is strong evidence that these Late Holocene coastal changes are not a product of fluctuations of sea level, but reflect palaeoseismic events. The sequence of the latter is at variance with models of seismic deformation deduced from a wide range of observations in different tectonic environments, including coastal uplifts near major trenches: according to these models, strain buildup and release through earthquakes is described as a cyclic and rather uniform process, the earthquake cycle. In this process, the permanent seismic deformation accumulates after each earthquake to produce geological features, while the long-term deformation rate is approximately equal to the short term one. Obviously this is not the case with West Crete. The unusual pattern of seismic deformation in this island has been observed in other cases as well, but its explanation is not easy. The juxtaposition of different earthquake cycles, variations in the source and rate of stress or internal deformation of the uplifted hanging wall of a thrust in the pre-seismic period are some possible explanations for this unusual pattern of earthquake cycle in Greece.


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