Volcanic lateral collapse during arc–continent collision? Clues from Lutao Island (Northern Luzon Arc)

Lateral collapses, also referred to as sector or flank collapses, are common in various types of volcanoes, particularly in island arc systems. Taiwan is situated in an active oblique collision zone, where the northern Luzon Arc converges with the Eurasian continental margin. Lutao volcano represents the last uplifted island that has not yet fully accreted into Taiwan, providing a unique opportunity to study volcanic evolution in the northern Luzon Arc during the collision process. This study focuses on the volcanic products of Lutao volcano, examining their spatial distribution and characterizing their occurrences. The seven recognized lithofacies are categorized into three lava coherent facies and four volcanic-breccia facies (one hyaloclastite, one lahar, and two pyroclastic density currents), distributed across four formations on Lutao Island. By integrating these findings with existing topographical data, we propose a revised eruption model, suggesting that the main eruption crater was located on the island’s eastern side and collapsed during the arc–continent collision. In addition, we extend this model to other island volcanoes now incorporated into Taiwan’s Coastal Range, further investigating the implications for volcanic behavior in these regions.