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Monthly archives: June, 2021

Types of Earthquake waves

An earthquake is caused by the seismic waves generated by the transverse movement of landmasses at plate tectonic boundaries, volcanic eruption, compression in the earth’s crust, groundwater extraction, geothermal drilling, construction of tracking, and injection wells, and havoc of a powerful nuclear bomb blast. All these events cause seismic waves. The seismic waves spread spreads …

Seismograph

”Seismographs” or ”Seismometers” are instruments, which detect and record earthquake waves. A seismograph contains a heavyweight suspended from a support, which is attached to bedrock. When seismic waves from a distant earthquake reach the instrument the inertia of the weight keeps it stationary, while the earth and support vibrate. The movement of the earth in …

Earthquakes

1. Introduction to an Earthquake An Earthquake may be defined as the shaking and trembling of the Earth’s surface caused by sudden releases of stress with the crust of Earth. Thus an earthquake releases the energy that has been gradually stored through the stress of increasing deformation of rocks. The released energy takes the form …

Springs and their types

What is a spring? When the groundwater flows out at the ground surface, it is called a spring. In other words, the extrusion of the groundwater above the ground surface is known as the spring. The springs are formed at places where the water table intersects the ground surface. Due to the sudden inclination and …

Groundwater in Coastal Areas

Under islands and near sea coasts, the freshwater extends to a considerable depth in the aquifer below sea level. As a result, the underground boundary between the fresh water and saltwater of the sea is inclined as shown in the following figure. If withdrawal by pumping is not excessive, the recharge of fresh water on …

Pumping of wells

In a well, drilled to an unconfined aquifer, the water will always stand in it at the level of the water table when the pump is not operating. As soon as the pump starts, the water level in the well starts dropping. The distance by which the level in the well is lowered below the …

Wells and their types

Wells: The most common device used by men for tapping groundwater is the well. The well is a vertical opening or shaft-hole excavated into the zones of saturation. Wells serve as reservoirs into which groundwater moves and from which it can be pumped to the surface. The amount of water that a well will yield …

Movement of Ground water

The groundwater moves very slow and percolates through pores, spaces, and other openings in the rocks. The movement of groundwater is measured in meters or centimeters per day. Although rates of tens of meters per day have been measured occasionally, while a rate of 12-15 meters per day is considered high. The movement of the …

Occurrence of ground Water

Groundwater is the water present beneath the ground surface. Groundwater occurs in abundance under the ground surface, which constitutes more than 30% of all fresh water on the globe. Groundwater has been percolated all through the top crustal surface of the earth. Beneath most of the land areas the groundwater occurs in three zones: (i) …

Ground Water

All water occurring beneath the ground surface is known as ”Ground Water”. It has been estimated that the volume of water in the upper 0.8 km of the continental crust is nearly 20 times greater than the combined volume of water in all lakes and rivers. The chief source of groundwater is the downward percolation …