Is it possible that very near surface structural and geomorphological features are affected by structures located tens of kilometers beneath?
which is the best geophysicsl method that could visualize and model this phenomena?
Hi,
it depends on the type of loading and loading amplitude, and on the soil properties. Consider a meteorite impact at one extreme and a hammer blow at the other. The waves propagation from the source can be measured and visualized using the methods of seismology.
Regards
Thaks for answering Mr.Aubram ,
It is for sure that seismic waves of the meteorite impact propogate through the deep ground , but the question is how can folding and faulting in tens of kilometers depth reflect on the surface as a structural and geomorphological features . I believe that a combination of seismic , gravity, deep VES and magnetic geophysical surveys would work to visualize the transformation in deformation from high depths to shallow depths.
Regards.
Dear Dr. Alkhafaji,
you need not go for away from your domicile. Have a look at the Dead Sea Transform Fault (DSTF) separating two prominent plates from each other. The tectonic processes did not proceed without leaving their imprints on the geomorphology (mass wasting) and sedimentology (seismites). I refer to two papers which you can download from the RG server:
DILL, H.G., BOTZ, R., BERNER, Z. and ABU HAMAD, A. M. B. (2010) The origin of pre – and syn-rift, hypogene Fe-P mineralization during the Cenozoic along the Dead-Sea-Transform Fault, Northwest Jordan.- Economic Geology, 105: 1301-1319.
see, e.g., Fig. 7c
DILL, H.G., HAHNE, K. and SHAQOUR, F. (2012) Anatomy of landslides along the Dead-Sea-Transform Fault System in NW Jordan.- Geomorphology, 141-142: 134-149.
The epicenter is located very deep but the outward appearance in terms of geomorphology and sedimentology is visualized at very shallow depth and can be discovered at outcrop. If you need more information consult my papers about Nepal, where one of the devastating earthquakes only recently struck.
Deep crustal processes can easily be correlated with near-surface geological features.
With best regards
H.G.Dill
Dear Dr Alkhafaji,
Large geomorphological landforms are frequently related to deep structural features. The effects of weathering and erosion tend to enhance. Rift valleys and graben structures are the result of magma upwelling and the pulling apart of the crust. Dome structures are usually underlain by magma chambers that have pushed the overlying strata up. In our area we have a perfect example of inverted relief, where the underlying anticlinal/synclinal folding of the Devonian sandstone has been subject to prolonged erosion. This has been most effective along anticlinal axes, in that the strata has been subjected to brittle fracture due to stretching of the rocks; rocks in synclinal folds on the other hand are compressed, making them more resistant to erosion. The result is that rivers and valleys tend to occupy anticlinal fold axes and synclines form the high ground in between (see attached photo; the model represents an area 20km width from Inverness to Dingwall). Such structures must be common in Iran and Afghanistan and possibly in Iraq. Hopes this helps.
George Strachan
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