Geophysical Update October 1, 2023

Geophysical Updates – October 1, 2023

Peninsular India's Seismicity and Challenges

Peninsular India has historically been a region of low seismic activity due to its old geological structure and compact landmasses.

Key Features:

• Volcanic origin: The Deccan Traps are formed from volcanic rock.
• Stable landforms: The region has stable landmarks and notable rift structures, such as the Narmada Rift.
• Low earthquake risk: The area has relatively low vulnerability to earthquakes, although there are occasional crustal faults like the Bhima Fault.

Recent Seismic Emergence:

In recent years, Peninsular India has started witnessing an increase in seismic activity:

• Intense earthquakes have occurred sporadically.
• Landslides and rock falls have become more frequent.
• Mild tremors have been recorded in parts of the Deccan region.

Reasons for Increased Seismicity:

• Dam-induced seismicity has led to increased geological instability.
• Unsustainable infrastructure development contributes to stress on the land.
• Changes in river patterns are influencing tectonic conditions.
• The burden of tourism in hilly regions adds to environmental stress.

Way Ahead:

India must integrate the Sendai Framework into its disaster management strategies to prepare for future seismic risks.

Arabian Sea Cyclone Surge

The Arabian Sea has experienced an increasing number of destructive cyclones, diverging from its historical patterns.

Conventional Conditions of the Arabian Sea:

• Cooler ocean temperatures traditionally kept cyclone activity low.
• Lower atmospheric wind circulation contributed to fewer cyclones.
• High-pressure systems often led to descending air, suppressing cyclone formation.
• Cyclones were previously rare in this region.

Reasons for Cyclone Surge:

• Rising ocean temperatures are contributing to more frequent cyclones.
• Bay of Bengal cyclones are shifting westwards to the Arabian Sea.
• Changing wind patterns and upper air divergence are encouraging cyclone development.
• Frequent low-pressure systems create favorable conditions for cyclone formation.
• Global climate change is intensifying these shifts.

Way Ahead:

India needs to focus on disaster preparedness, enhance climate research, and strengthen early warning systems to mitigate the impact of future cyclones. An integrated cyclone mitigation system should be implemented on all coasts.

Rossby Waves and Their Impact

Rossby waves are powerful jet streams that encircle both poles at altitudes of 8 to 13 kilometers and play a vital role in shaping the Earth’s climate.

Features of Rossby Waves:

• Stronger in summer, leading to intensified weather patterns.
• Anticlockwise circulation around the poles influences global climate.
• Guided by the Coriolis force, affecting weather systems worldwide.

Role in Earth's Climate:

• Restrict cold winds to polar regions, maintaining global temperature balance.
• Influence precipitation patterns, bringing snowfall in colder areas.
• Weak Rossby waves can cause cold winds to spill into Europe and North America.
• Impact planetary wind systems, affecting weather dynamics globally.
• Regulate temperatures around the poles, crucial for climate stability.

Understanding Rossby waves is essential for grasping the complexities of the global atmosphere and climate.

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