This proposal evaluates the potential volcanic instability and flank-collapse hazards of Mt. Malindig (Marinduque) by framing the edifice as a possible spreading volcano influenced by both its internal stratigraphy and regional tectonics. Existing geomorphic and geologic indicators in and around the volcano, including suspected debris-avalanche hummocks and amphitheater-like scarps, suggest that large-mass wasting may have occurred in the past and could recur under favorable conditions. The work specifically considers how the NW–SE–trending Central Marinduque Fault and the volcano’s lithologic architecture may promote gravitational spreading, weaken sectors of the cone, and localize future collapse pathways, with the end goal of producing a defensible basis for hazard assessment relevant to nearby communities.
The study integrates field mapping, remote sensing, petrography, structural analysis, and analog modeling. Fieldwork focuses on 1:25,000-scale geologic and structural mapping around Mt. Malindig, particularly along the northern flank where potential debris-avalanche deposits have been reported; this includes outcrop description, lithologic verification of hummocks, and systematic structural measurements (e.g., joints and fractures) while documenting the sense of movement of key structures, especially the Central Marinduque Fault. Remote-sensing interpretation uses DEM-derived hillshades and GIS-based lineament mapping (with manual delineation of rectilinear and curvilinear features) to identify volcanic-tectonic features (e.g., domes, lava flows, pyroclastics, alluvial fans, and suspected avalanche deposits) and to guide targeting of field checks. Petrographic analysis of selected weathered lithologies is conducted using a polarizing microscope to characterize mineral assemblages, textures, and alteration patterns that may relate to mechanical weakness. Structural datasets are evaluated using rose diagrams and compared with mapped lineaments; data processing and plotting are supported by software tools (e.g., QGIS and Win-Tensor). For the experimental component, a scaled analog model is constructed using a sand–plaster mixture to represent the volcano and a mechanically driven basal/side-plate setup to simulate left- or right-lateral strike-slip motion and associated spreading behavior; cone and sand-cone experiments are run under controlled parameters (following established scaling approaches) to reproduce deformation styles, delimit instability zones, and compare experimental structures against mapped field/remote-sensing patterns.
The project is designed to produce hazard-relevant outputs that are difficult to obtain from mapping or remote sensing alone: (i) a defensible identification of sectors most susceptible to volcanic spreading and flank collapse, (ii) an evidence-based interpretation of whether suspected hummock deposits are consistent with debris-avalanche emplacement, and (iii) a mechanistic explanation for how regional faulting may amplify gravitational instability at Mt. Malindig. By combining validated field observations with controlled analog experiments, the study aims to move beyond “possible” interpretations toward testable, map-ready delineations of zones of weakness and steepened slopes that can inform local risk assessment and management. The outputs are also expected to strengthen baseline geologic understanding of Mt. Malindig’s edifice evolution and provide a transferable workflow for assessing flank-collapse potential in similarly structured Philippine volcanoes where fault-volcano interactions are a key uncertainty.
This research addresses UN Sustainable Development Goals for Sustainable Cities and Communities (SDG 11) and Industry, Innovation, and Infrastructure (SDG 9)
Cover photo of Mt. Malindig from: https://timogkatagalugan.com/index.php/2023/09/06/mount-malindig/
