Find Out What Triggers Earthquakes in the Earth's Crust, How It Originates

The immediate cause of shallow earthquakes is the sudden release of stress along a fault, or fracture in the earth's crust, resulting in movement of the rocks.

Most earthquakes originate from the compression and tension that build up at the margins of the huge moving plates that make up the earth’s surface. The immediate cause of most shallow earthquakes like in Nepal now, occurring within 70 km of the surface, is the sudden release of stress along a fault, or fracture in the earth’s crust, resulting in movement of the opposing blocks of rock past one another.

The focus of an earthquake is the point where it originates within the earth. The earthquake epicenter is the point on the earth’s surface directly above the focus.

Aftershocks of the Nepal Earthquake are Likely to Continue, Says Meterology Department
More than two-and-a-half dozen aftershocks of magnitude four and above have been observed in the quake-hit Nepal. Northern India felt a few tremors too.

The size or magnitude of earthquakes is determined by measuring the amplitude of the seismic waves, which depends on many factors such as the magnitude, distance from the epicenter, depth of focus, topography, and local ground conditions.

The area of Saturday’s earthquake in Nepal is the so-called Indus-Yarlung suture zone, where the Indian subcontinent collided 40 million to 50 million years ago with the Eurasian plate, creating the Himalayan mountain ranges which are still rising by around one centimeter a year as an ongoing consequence.

In areas underlain by water-saturated sediments, large earthquakes, usually magnitude 6.0 or greater, may cause liquefaction.

Artist Creates Sand-art to Raise Awareness About the Nepal Earthquake Victims
Sudarshan Patnaik, the Indian artist famous for his sand sculptures, said people from all over the world must help victims of the earthquake in Nepal.

Beneath the Kathmandu Valley is a 300-metre deep layer of black clay, the remnants of a prehistoric lake, which amplifies the damage caused by severe earthquakes. Studies have established that this region is prone to soil liquefaction in strong earthquakes, when vibrations can cause solid ground to collapse, swallowing buildings in the process.

The Indian subcontinent has a history of devastating earthquakes. The earthquake zoning map of India divides the country into four seismic zones - 2, 3, 4 and 5 - in which Zone 5 expects the highest level of seismicity and is referred to as the Very High Damage Risk Zone. Kashmir, the western and central Himalayas, the northeast region and the Rann of Kutch fall in this zone.

Nepal Earthquake: National Geophysical Research Institute to Asses Seismic Hazard Level
The earthquake that struck Nepal is understood to be a typical Himalayan earthquake caused by the collision of the Indian plate with the Eurasian plate.

Source-IANS

How Mount Everest Climbers Felt as Massive Earthquake Hit Nepal
As an earthquake hit Nepal, the climbers used social media to keep the world appraised of the loss of lives and destruction at the Himalayan base camps.