Slab Tear Beneath the Sunda Strait

Abstract

Slab tearing plays a critical role in subduction zones worldwide, as it facilitates mantle upwelling, influences magma generation, and leads to the formation of tensional structures, which may create favorable conditions for geothermal potential. Understanding its mechanisms and effects is essential for interpreting the complex geodynamics of convergent margins. This research investigates geodynamic processes in the Sunda Strait, focusing on slab tearing and its geological implications. Analysis of earthquake hypocenter data (1906–2025) reveals significant differences in slab depth between Sumatra and Java, supporting the slab tearing hypothesis. These differences arise from variations in the age and density of the subducting oceanic crust, causing sharp contrasts in slab dip angles. High heat flow in the eastern and northeastern Sunda Strait indicates mantle upwelling due to vertical and horizontal slab tearing, respectively. The presence of Sukadana Basalt (OIB-like) in eastern Lampung and normal faults in the Sunda Strait, along the eastern Lampung and western Java coasts further supports this hypothesis. Additionally, shifts in volcanic arc distribution and volcanic activity discontinuities confirm the tectonic effects of slab tearing. This study highlights how slab dip angle variations influence magma genesis and volcanic behavior. It also reveals the unique geodynamics of the transition zone between orthogonal and oblique subduction. The findings enhance understanding of geological processes in the Sunda Strait and provide insights for future research on slab tearing and regional tectonics.