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Earthquakes Earthquakes are the greatest threat to the Himalayas. Almost all of the Himalayas are under great danger of the seismic activity or the earthquakes. The reverse fault is involved in this boundary because the plates are converging or coming toward each other. As the Indian Plate is pushing against the Eurasian Plate, the stress is building up and there have been many earthquakes in this region as a result of that and there are still more to come. We can tell this because we know that the Indian Plate is pushing against the Eurasian Plate which causes stress against the plates and even more threat of the severe earthquakes. Earthquakes are basically thought to have been caused by stress. The stress causes the crust to bend. Suddenly when the bond brakes, the crust that had been bends recovers or returns to its original position. This is called the Elastic Rebound Theory. Elastic Rebound Theory is what has thought to cause most of the earthquakes that we experience today. Debris worn from the land was deposited into the Tethys Ocean as thick layers of sediments. The northward movement of the plate pushed forward the ocean floor up and over the crunched edge of the Eurasian plate which caused very severe earthquakes at that time and caused Himalayas to form. Running across the Tethys Ocean was a deep trench. Indian and the Eurasian plate drifted closer the crust under the ocean was dragged downward along the trench, and the ocean sediments built up at the edge of the plate. Those are currently at the top of the Himalayas. The Tethys Ocean gradually closed up. About 45 million years ago, Indian and Eurasian Plate crashed. Continental crust is light so it was thrust up into complex folds to form mountains. All the sediments that were laid down in the ocean also buckled and folded. This caused the severe earthquakes and Himalayan Chain to form. The Himalayas were formed by the collision of Indian Plate with the Eurasian Plate. The mountain building process is still going on because the Indian Plate is still moving towards the Eurasian Plate. The Indian Plate is pushing the Eurasian Plate northward at the rate of about 2 cm per year (growing rate of our finger nails). This means that in every 100 years India moves 200 cm north against the Eurasian Plate. The colliding force builds up pressure continually for several years and this pressure is released in the form of earthquakes from time to time when the plates move according to the Elastic Rebound Theory. The cold barren deserts regions have experienced less devastation form earthquakes due to less population. Four major earthquakes have occurred in the Himalayan region in the past 100 years. The famous earthquake that hit Nepal in 1933 killed thousands and destroyed a lot of property in Nepal and northern India. Several earthquakes have occurred after that. The Indian Himalayas have experienced some significantly strong earthquakes in the past few decades. Some these earthquakes were as dangerous as the one in Kobe, Japan. From 1989 to 1998 USGS has ranked the Indian earthquakes to be the 8th strongest ones in the world |
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| Kinnaur Earthquake This earthquake struck in the early afternoon of January 18, 1975. It caused disasters in parts of the Kinnaur, Lahaul and Spiti regions of India. Seismographers think that the movements along the Kaurik Fault caused this earthquake to occur which killed hundreds of people and cause severe damage of property. Two massive landslides took place during the earthquake. One of them was near Maling in the Spiti Valley. The other one blocked the Paro chu River near Sumdo. Many smaller occurrences of slope failure wre cuased by this earthquake. Communications failed and helicopters were used to bring relief. The magnitude of this earthquake was about 7.8 on the Richter Scale. Dharchula Earthquake This earthquake struck Dharchula and the surrouding areas of Pithoragarh District in the Kumaon Himalayas. Thsi Earthquake took place in December 1980. Displacement along the fault is thought to cause the earthquake which affected the parts of the inner dry valleys of Pithoragarh District. The magnitude of this earthquake was about 8 on the Richter Scale Uttarkashi Earthquake This earthquake took place in the early morning of October 14, 1991. This earthquake was so severe that it shook most parts of Uttarkashi and Chamoli districts of Garhwal. This earthquake was very severe and caused a lot of lives and property damage. The communication was destroyed and the region was cut off from the rest of the world due to the debris. Landslides also occured at many locations. The magnitude of the earthquake was about 7.9 on the Richter Scale. |
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