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Tibet Earthquake
Context:
Recently Tibet was hit by a powerful earthquake measuring around 7 on the Richter scale, resulting in significant loss and damage.
More on News:
- The earthquake claimed the lives of approximately 100 people and caused the destruction of about 1,000 homes.
- The epicentre of the earthquake was located about 75 kilometres northeast of Mount Everest, near the border with Nepal, although no major damage was reported in Nepal.
- According to the United States Geological Survey (USGS), at least 10 earthquakes of magnitude 6 or above have occurred in this region over the past century.
Location Details:
- Tingry County: Located about 4-5 km above sea level with a population of around 7,000 people.
- Spiritual Significance: The county is home to the Panchen Lama of Tibetan Buddhism.
- Tourist Impact: The region is a gateway to Mount Everest but has fewer tourists during winter. Access to the region has been closed by Chinese authorities since the quake.
Why is the Region Earthquake-Prone?
- Tectonic Plate Movements: The Earth’s crust and upper mantle consist of 15 major and minor tectonic plates. Earthquakes result from movements along faults—fractures in tectonic plates.
- Mechanism of Earthquake Formation: Friction at the edges of tectonic plates prevents them from moving smoothly. When accumulated stress overcomes this friction, it releases energy as seismic waves, causing the ground to shake.
- For instance, the 2023 Turkey earthquake was caused by interactions between the African, Eurasian, and Arabian plates.
- Role of Convection Currents: Rising temperature and pressure within the Earth’s mantle create convection currents that drive the movement of tectonic plates.
Geological Context and Significance:
- Lhasa Terrane: The quake’s mainshock may have originated in the Lhasa terrane, an important geological feature in Tibet.
- Hydroelectric Project: The Lhasa terrane is also home to China’s large hydroelectric project, which could impact the Yarlung Tsangpo River (Brahmaputra), raising concerns about its perennial status and effects on downstream regions like Arunachal Pradesh and Assam (India).
- Himalayan Water Significance: The Himalayan region is referred to as the “third pole” due to its vast water reserves (rivers, glaciers, lakes), affecting millions who rely on it. Earthquakes can destabilise glaciers, lakes, and rivers, potentially causing floods and other disasters.
The Himalayan Region: A High-Risk Zone:
- Formation of the Himalayas: The Indian Plate collided with the Eurasian Plate around 40–50 million years ago, uplifting the land to form the Himalayan mountain range.
- The Eurasian Plate is now subsiding beneath the Indian Plate, a process that continues today.
- Convergence Rate: The India-Eurasia plate collision occurs at a relative rate of 40-50 mm per year, making the region highly seismically active.
- Peculiar Tectonic Activity: In addition to the Indian Plate subducting under the Himalayas, the Eurasian Plate is being subducted beneath the Pamir mountains, creating multiple fault lines.
- This region serves as a convergence point for several seismic forces.
- Historical Earthquakes: Since 1950, at least five earthquakes of magnitude greater than 7 have hit the Hindu Kush region.
Threat of Future Earthquakes:
- Seismic Hazard in Western Himalayas: The western Himalayas are among the world’s most dangerous seismic zones. The 2,500-km stretch from Hindu Kush to Arunachal Pradesh is considered overdue for a major earthquake (magnitude >8).
- Energy Accumulation: The continuous interaction of tectonic plates stores enormous elastic energy along fault lines, which can only be released through massive quakes.
- Research Insights: A 2017 study in Quaternary International analysed incomplete ruptures of the Main Himalayan Thrust, including the Gorkha earthquake of 2015.
- Lead author Roger Bilham highlighted the presence of “reservoirs of elastic energy” waiting to be released in the Himalayas.
- Unpredictability and Risk: Earthquakes remain inherently unpredictable, but the potential damage from a significant event in this region could be catastrophic.
