A. Aoudia, ICTP

Lesson number 15 (A. Aoudia)

Lithospheric deformations

In this lesson is described how deformation of earth surface is measured by geodetic techniques. The GPS measurements are explained in detail. These measurements are useful to determine plate motions adn to measure plate boundary deformation. The modern methodologies can reach a precision of about 5 mm.

The crustal deformation is involved in the earthquake generation. The elastic rebound theory by Reid to explain the origin of earhquakes. Elastic rebound theory states that as tectonic plates move relative to each other, elastic strain energy builds up along their edges in the rocks along fault planes. Since fault planes are not usually very smooth, great amounts of energy can be stored (if the rock is strong enough) as movement is restricted due to interlock along the fault. When the shearing stresses induced in the rocks on the fault planes exceed the shear strength of the rock, rupture occurs. Earthquakes are therefore caused by a sudden slip on a fault.

Earthquakes, elastic rebound and deformationsEarthquakes, elastic rebound and deformations