Magma Overpressure Estimation from Partially Exposed Dykes
Biswas et al. (2023 & 2025)
Knowledge of complete dyke dimensions is crucial to determine the actual aspect ratio which is indispensable in estimating their magma overpressure, depth of origin and even explosivity potential of fissure eruptions. A dearth of completely exposed dykes imposes considerable uncertainty on estimates of their aspect ratios. Therefore, we introduce mathematical methods of estimating complete dyke dimensions from their partial exposures consisting of at least one visible tip or devoid of any tip. The methods are built upon the idealized canonical model of opening mode fractures and utilize the elliptical shape of opening of dykes in 2D as formulated in the model. Subsequently, the calculated aspect ratio is used to estimate magma overpressure for a dyke following Gudmundsson (1983). Although developed for dykes, the methods have potential for wider application, since they can be used fundamentally to predict complete dimensions of any elliptical shaped natural features from their partial exposures.
1. Partial dyke exposure with one visible tip
This method (Biswas et al., 2023) solves the equation of ellipse which is the predicted shape of dyke opening in the canonical model using every possible combination of two points lying on the dyke margin measured from the observed tip to estimate the full length, maximum width and aspect ratio.
Cite as: "Biswas, S. K., Saha, K., Das, G., and Mondal, T. K. (2023). Estimation of magma overpressure from partially exposed dykes-A new approach. Journal of Structural Geology, 168, 104822."
https://doi.org/10.1016/j.jsg.2023.104822
Estimate complete dyke dimensions
2. Partial dyke exposure with no visible tip
This method (Biswas et al., 2025) utilizes discrete derivatives derived from limited outcrop measurements made on dyke margins in the differential equations of ellipse, which is the predicted shape of fracture opening in the canonical model, to estimate the full length, maximum width and aspect ratio.
Cite as: "Biswas, S.K., Mondal, T. K., Saha, A., Mukhopadhyay A.K., and Mukherjee A. (2025). Estimating Complete Dyke Dimensions from Partial Exposures. Journal of Structural Geology, 192, 105350."
https://doi.org/10.1016/j.jsg.2025.105350
