SEISMOGRAPH THE SCIENCE WHICH STUDIES EARTHQUAKES IN DETAIL IS KNOWN AS SEISMOLOGY. SEISMOGRAPH AN INSTRUMENTSWHICH MEASURES THE INTENSITY OF EARTHQUAKES IS KNOWN AS SEISMOGRAPH.

EARTHQUAKE A VIBRATION OR SHAKING OF THE CRUST MAY BE CALLED AS EARTHQUAKE. IMPORTANT CAUSES OF EARTHQUAKE ARE 1] FOLDS 2] FAULTS 3] LANDSLIDES

Fault, in geology, is a fracture in the Earth's crust along which a section of the crust has been displaced relative to another section, in response to forces of tension or compression as a result of tectonic movement. This movement may be in a vertical or horizontal direction, or a combination of the two. The fracture may range from centimeters to hundreds of kilometers long, such as the San Andreas Fault in California. The movements at fault lines may be sudden if generated in a severe earthquake. FAULTS

A single fold is a hinge defined by the maximum curvature of the beds. The hinge line joins the points of maximum bending along a bed. The axial surface, or plane, passes through the hinges of successive beds, while the axis of the fold is any line on the bed which is parallel to the hinge line. When the axis is inclined to the horizontal, the fold is said to plunge. Axial surfaces are vertical in upright folds, while surfaces dip at varying angles and are sub horizontal in recumbent folds. In the latter, the upper limb may become detached and thrust one over the lower to form a structure known as a nappe, which is common in the Alps. FOLDS

Landslide, is a descent of a mass of earth and rock down a mountain slope. Landslides may occur when water from rain and melting snow sinks through the earth on top of a slope, seeps through cracks and pore spaces in underlying sandstone, and encounters a bed of shale inclined towards the valley. The water collects along the upper surface of the shale, which it softens to form slippery clay. If the support is sufficiently weakened, a mass of earth and rock slides down along the well-lubricated bedding of shale. LANDSLIDES

EARTHQUAKE WAVES AT THE TIME OF EARTHQUAKES THREE TYPES OF WAVES ARE PRODUCED 1] PRIMARY WAVES. 2] SECONDARY WAVES. 3] LONG WAVES.