Monthly archives: June, 2021

How to locate the epicentre of an Earthquake?

The first thing you need to find the location of an earthquake is the recorded seismograms of three differently located seismographs. You will also need a map of the world, a ruler, a pencil, and a compass for drawing the lines for locating the epicenter. Now you can easily find the location of the epicenter …

Large amount of mercury found in the glaciers of Greenland

Scientists were alarmed at the amount of dissolved mercury they found in rivers and fjords. The heavy metal raises concerns for the health of indigenous communities. And with global warming, the problem may get worse. When British environmental geochemist Jon Hawkings arrived in Greenland for the first time in 2012, he was impressed. “It’s mind-blowing: You …

Earthquake intensity scales

The effect of an earthquake is, generally, stronger near the epicenter and decreases gradually outwards. To have an idea about the intensity of an earthquake in different areas, intensity scales have been devised. The two commonly used intensity scales are : (i) Rossi Forel Scale, and (ii) Richter Scale (1). Rossi Forel Scale: The earthquake …

Origin of earthquakes (Elastic Rebound Theory)

Earthquakes are classified on two bases, one is surface causes, volcanic eruption, and tectonic movement. Among these types, volcanic earthquakes are the most common and disastrous, therefore discussing the tectonic type of earthquakes is very important. The reason behind tectonic earthquakes is the tectonic movement of crustal plates. There are three types of tectonic movements. …

Classification of Earthquakes

Classification I. Depending upon their mode of origin, the earthquakes are classified into the following groups. Earthquake due to surface causes: Earthquakes may be generated by landslips and collapse of the roofs of underground caverns and other surface disturbances. Most of these are very minor, and some are even rarely felt. All causes of an …

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 …