What is the difference between deformation and stratification

In the layer model, the uplift is reduced by more than 50 per cent with respect to the four-layer model. This is due to a combination of the reduction of rigidity and density contrasts at the appropriate boundaries in the layer model with respect to the four-layer volume-averaged model. For longer distances we find larger negative displacements, up to 15 cm for the two four-layer models. In this case we also notice that the family of four-layer models substantially overestimates the amplitude of the deformation.

Displacements are large for distances of 10— km, with a negative peak at around km where the displacement reaches 3—7 cm in the coseismic case and 5—10 cm in the post-seismic case. Also for this component of the displacement, we obtain a reduction of coseismic and post-seismic displacements of about 50 per cent when crust, lithosphere and upper mantle are stratified.

This reduction is essentially due to the overall reduction in the rigidity and density of the crust and lithosphere for the stratified models, in particular at the earth's surface where the deformation is sampled. The displacements are shown in Figs 5—7. The displacement is substantially different from zero between 10 and km from the fault; the largest uplift is located at approximately km in the coseismic case and is displaced at larger distances due to post-seismic deformation.

Comparison of the three models shows that in the elastic limit the P1 model and the four-layer model predict similar behaviour, while in the post-seismic case they show large deviations. The volume-averaged model produces smaller displacements than the fixed boundary contrast model: the greatest uplifts along the line are 70 and 30 cm respectively.

When we consider the stratification of the earth in 10 layers, we obtain even lower displacements: the greatest uplift is approximately 15 cm.

Unlike from the vertical displacement, these fields are characterized by significant amplitudes for distances larger than km. The greatest displacement is at 50—80 km. Comparing the horizontal displacements due to different earth models, we reach the same conclusions as in the case of vertical movements: the layer model always predicts smaller displacements than the four-layer models due to the reduced rigidity and density.

These results are in agreement with those obtained for the dip-slip fault, although for the strike-slip fault we obtain larger deviations between the two four-layer models. Finally, for all earth models and in all directions we observe an amplification of the displacements for long times after the earthquake compared to the elastic displacements. In general, deformation due to strike-slip faulting is very sensitive to the elastic and rheological parameters of the layers.

Comparison of the results for finite faults for different earth models shows large deviations between the family of four-layer models and the model in which the lithosphere is realistically stratified in predictions of the coseismic and post-seismic deformation of the earth's surface. For both dip-slip and strike-slip faulting the surface deformation is considerably reduced in the layer case with respect to the corresponding four-layer volume-averaged models because of the reduction in rigidity and density of the uppermost portion of the earth.

The deformation due to a strike-slip fault is generally more sensitive to rheology than that produced by a dip-slip fault when the layering is fixed. For large and deep earthquakes, deviations between the models with a homogeneous lithosphere and the layer model range from a few centimetres to tens of centimetres, where the deformation pattern shows the largest signal for both dip-slip and strike-slip faulting and coseismic and post-seismic deformation.

GPS surveying, which can be performed soon after the occurrence of earthquakes, can resolve vertical and horizontal displacements with an accuracy of 3—5 cm, over a baseline of 10—20 km, which implies that in order to interpret correctly the deformation pattern in seismogenic regions, synthetic earth models with a realistic lithospheric stratification should be considered. The accuracy of radar interferometric deformation measurements is limited by the amount of disturbance of the surface characteristics between the two SAR acquisitions and the contribution of atmospheric signals in the interferograms.

The former is dependent on vegetation and land-use, for example, while the latter is mainly influenced by water vapour in the atmosphere. As long as correlated areas such as cities or infrastructure are visible in the image, the accuracy of the technique ranges from 0. Finally, we note that we have neglected some other important features that can considerably influence co- and post-seismic behaviour due to finite faulting, of which we consider compressibility, lateral variations in the earth models and non-linear rheologies to be the most important.

Implementation of compressibility in the lithospheric layers is under way, from which we expect deviations with respect to incompressible models as high as 30—40 per cent, especially in the coseismic case. Non-linear rheologies would affect the transient deformation, which is not considered in the present analysis. We thank Riccardo Barzaghi, Politecnico di Milano, for important discussions.

An anonymous referee is thanked for constructive remarks on the original manuscript. Cesca S. Google Scholar. Google Preview. Dziewonski A. Anderson D. Preliminary reference Earth model , Phys. Earth planet. Inter , 25 , — Fung Y. Hanssen R. Piersanti A. Spada G. Sabadini R. Bonafede M. Global post-seismic deformation , Geophys. Int , , — Global postseismic rebound of a viscoelastic earth: theory for finite faults and application to the Alaska earthquake , J.

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Volume Influence of lithospheric and mantle stratification on co- and post-seismic deformation due to finite faults. Cesca , S. E-mail: simone sabadini. Oxford Academic. Cite Cite S. Select Format Select format. Permissions Icon Permissions. SUMMARY Coseismic and post-seismic deformation in the fully relaxed state following large earthquakes is modelled for finite faults by means of multilayered, viscoelastic, self-gravitating, hydrostatically pre-stressed, spherical earth models based on the preliminary reference earth model PREM with a Maxwell rheology.

Open in new tab Download slide. Modellistica delle deformazioni cosismiche e postsismiche indotte dai terremoti. Google Scholar Crossref. Search ADS. Global postseismic rebound of a viscoelastic earth: theory for finite faults and application to the Alaska earthquake. Influence of lithospheric and mantle stratification on global post-seismic deformation. The effects of postseismic motions on the moment of inertia of a stratified viscoelastic earth with an asthenosphere.

The elasticity theory of dislocations in real earth models and changes in the rotation of the earth. Rappresentazione di sorgenti sismiche in geometria sferica: effetti post-sismici in Alaska e Nord America. Jones; Deformed cross-stratification in Cretaceous Bima sandstone, Nigeria.

Journal of Sedimentary Research ;; 32 2 : — The examples described are believed to illustrate different stages of a single type of isoclinal deformation. Various modes of origin are considered and it is concluded that the mechanism of disturbance was sliding caused by earthquake shock.

Shibboleth Sign In. OpenAthens Sign In. Institutional Sign In. Sign In or Create an Account. User Tools. Sign In. Advanced Search. Skip Nav Destination Article Navigation. Close mobile search navigation Article navigation. Volume 32, Number 2. Previous Article Next Article. Article Navigation. Other June 01, Jones Glyn P. Google Scholar. Journal of Sedimentary Research 32 2 : — Article history first online:. Abstract "Deformed cross-stratification is present in the Bima sandstone at many localities in northeastern Nigeria.

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