Receiver Function Imaging of Himalayan Crustal Deformation

Introduction to Himalayan Tectonic Dynamics

The eastern Himalayan region, located at the junction of the Indian and Asian plates, is a geological hotspot characterized by complex crustal deformation. Despite extensive research, the mechanisms driving crustal deformation during the ongoing collision of these tectonic plates remain unclear. To address this knowledge gap, researchers have employed high-resolution receiver function imaging along a dense NW-SE-trending array of seismic stations.

Research Overview: Seismic Imaging in the Eastern Tibetan Plateau

Objectives and Methodology

This study aimed to:

• Investigate how the crust deforms in the eastern Himalayan tectonic belt.
• Identify dominant mechanisms, such as backwash and pure shear, influencing crustal deformation.
• Map detailed crustal structures using a dense seismic station array.

The research utilized 200 SmartSolo IGU-16HR 3C seismic sensors, strategically positioned along the Himalayan tectonic junction. These advanced tools enabled the acquisition of high-resolution data, offering unparalleled insights into subsurface structures.

Key Observations

1. Low-Velocity Zones:
   • Identified below the western Lhasa Massif and the High Himalayan region at depths of 18-20 km.
   • Additional zones found beneath the Yarlung Tsangpo Suture Belt at depths of 10-30 km, featuring two westward-trending types.
2. Crustal Discontinuities:
   • An eastward-dipping internal crustal discontinuity was observed beneath the Ankiga-Motoro shear zone.
   • A pronounced Moho dislocation extending 7 km was detected, signifying significant tectonic activity.

Mechanisms of Crustal Deformation

The findings reveal that two primary mechanisms dominate the deformation of the Himalayan crust:

• Backwash Mechanism: Gravitational forces drive vertical uplift or subsidence, influencing the crust’s vertical movement.
• Pure Shear Mechanism: Parallel forces act in opposing directions, causing horizontal stretching and compression of the crust.

Role of SmartSolo IGU-16HR 3C Seismic Equipment

The SmartSolo IGU-16HR 3C sensors were pivotal in achieving high-resolution imaging of subsurface structures. These sensors excel in detecting seismic events and providing detailed receiver function data, which:

• Enhanced understanding of partially molten and fluid-filled low-velocity zones.
• Enabled accurate mapping of crustal discontinuities and tectonic structures.
• Offered insights into the interplay of gravitational and shear forces within the crust.

Implications for Geological Research

This study provides critical insights into the tectonic dynamics of the eastern Himalayan region. The ability to differentiate and estimate the dominance of backwash and pure shear mechanisms has significant implications, including:

• Advancing knowledge of Himalayan tectonics and crustal evolution.
• Informing seismic hazard assessments in one of Earth’s most active tectonic zones.
• Contributing to the broader understanding of plate collision dynamics and crustal deformation processes.

Conclusion

The integration of SmartSolo IGU-16HR 3C seismic sensors and receiver function imaging techniques has unlocked new perspectives on crustal deformation mechanisms in the Himalayan tectonic junction. These findings enhance our understanding of the geological processes shaping this region and lay the groundwork for future seismic research.