1950 Assam–Tibet earthquake facts for kids
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| UTC time | 1950-08-15 14:09:34 |
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| ISC event | 895681 |
| USGS-ANSS | ComCat |
| Local date | August 15, 1950 |
| Local time | 19:39:34 IST |
| Magnitude | 8.7 Mw |
| Depth | 15 km (9.3 mi) |
| Epicenter | 28°22′N 96°27′E / 28.36°N 96.45°E |
| Fault | Main Himalayan Thrust |
| Type | Strike-slip |
| Areas affected |  India, Assam China, Tibet |
| Max. intensity | XI (Extreme) |
| Casualties | 4,800 |
The 1950 Assam–Tibet earthquake was a very powerful earthquake. It happened on August 15, 1950. This earthquake is also known as the Assam earthquake. It had a magnitude of 8.7, which is incredibly strong.
The earthquake's starting point, called the epicentre, was in the Mishmi Hills. This area is located between India and Tibet. It is the strongest earthquake ever recorded on land. It is also tied with the 2012 Indian Ocean earthquakes as the strongest Strike-slip earthquake ever. A strike-slip earthquake happens when two parts of the Earth's crust slide past each other horizontally.
The earthquake struck on a Tuesday evening at 7:39 pm Indian time. It caused a lot of damage in both Assam (India) and Tibet (China). About 4,800 people lost their lives. This earthquake is special because it was caused by two large landmasses crashing into each other. Most other very large earthquakes are caused by one plate sliding under another. People in the area also reported hearing very loud noises during the quake.
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How do scientists study past earthquakes?
Scientists wanted to learn more about earthquakes in Northeast India. So, they did studies in the field. Researchers from the National Geophysical Research Institute and the Institute of Physics, Bhubaneswar found clues.
They discovered signs of soil liquefaction. This is when soil acts like a liquid during shaking. They saw things like sills (flat layers of rock) and sand volcanoes. These were found in at least twelve trenches (long, narrow ditches) in alluvial fans and along the Burhi Dihing River Valley. These features were created by earthquakes long ago.
Scientists used Radiocarbon dating to figure out how old these deposits were. They found them to be about 500 years old. This matches up with an earthquake that was recorded in 1548.
What caused the 1950 Assam–Tibet earthquake?
The earthquake happened in a very rugged, mountainous area. This region is between the Himalayas and the Hengduan Mountains. The earthquake's center was just south of the McMahon Line. This line marks the border between India and Tibet. Both regions were badly affected.
This huge earthquake had a calculated magnitude of 8.7. It is considered one of the most important earthquakes studied since we started using special stations to measure them. It was the sixth largest earthquake of the 20th century.
What makes this quake unique is that it was not caused by an oceanic plate sliding under another (called subduction). Instead, it happened because two continental plates (large pieces of Earth's crust) crashed into each other.
Many smaller earthquakes, called Aftershocks, followed the main quake. Many of these aftershocks were magnitude 6 or higher. They were recorded by stations far away. This data showed that the aftershocks spread over a very large area. This area stretched from about 90 to 97 degrees east longitude. The main earthquake's center was near the eastern edge of this area.
What was the impact of the earthquake?
The 1950 Assam–Tibet earthquake had terrible effects on both Assam and Tibet. In Assam, 1,526 people died. In Tibet, about 3,300 deaths were reported. This means a total of around 4,800 people lost their lives.
The landscape changed a lot because of many rock falls. These happened in the Mishmi Hills and nearby forest areas. In the Abor Hills, 70 villages were destroyed. Landslides caused 156 deaths there. Landslides also blocked rivers that flow into the Brahmaputra.
In the Dibang Valley, a lake formed by a landslide broke open. Luckily, it did not cause any damage. But another landslide lake on the Subansiri River burst 8 days later. A huge wave, about 7 meters (23 feet) high, rushed out. It covered several villages and killed 532 people.
The earthquake caused more property damage in Assam than the 1897 Assam earthquake. Besides the intense shaking, there were also floods. Rivers rose high after the quake. They carried down sand, mud, trees, and all sorts of debris. Pilots flying over the most affected area saw huge changes in the land. This was mostly due to enormous landslides. Some of these landslides were even photographed.
In Tibet, Heinrich Harrer said he felt strong shaking in Lhasa. He also heard loud cracking noises coming from the ground. Aftershocks were felt in Lhasa for many days. In Rima, Tibet (now Zayü Town), a person named Frank Kingdon-Ward noted violent shaking. He saw many landslides and noticed that streams had risen. Helen Myers Morse, an American missionary in Putao, northern Burma, wrote letters home. She described the main quake, the many aftershocks, and the noise from the earth.
One of the aftershocks, which happened a few days later, was felt more widely in Assam than the main quake. This made some journalists think that the later shock was "bigger." They even thought it might be the greatest earthquake ever. This shows how people can confuse magnitude (the earthquake's strength) with intensity (how much shaking is felt in a certain place). The unusual sounds heard by Kingdon-Ward and others during the main earthquake have been studied specially. Even far away in Norway and England, water in lakes and pools sloshed back and forth. These are called Seiches.
Could another big earthquake happen?
An article in the magazine Science talked about the risk of future earthquakes. This article was published after the 2001 Bhuj earthquake. It said that 70 percent of the Himalayas could experience a very powerful earthquake.
This prediction came from studying old records of earthquakes in the area. It also assumed that since the 1950 Medog earthquake, enough movement has happened for another large earthquake to occur. In 2015, the Himalayas were hit by a 7.8-magnitude earthquake. Its center was further west in Nepal.
See also
In Spanish: Terremoto de Assam de 1950 para niños
- 1897 Assam earthquake
- 2009 Bhutan earthquake
- April 2015 Nepal earthquake
