3D matching positioning method for landslide using infrasound signal received by triangular pyramid vector array, based on ray theory

Several hours before landslides occur, part of the rock and soil body begin to burst, rub, and fracture, generating infrasound signals propagate outward. 3D advanced positioning of the landslide has remained unsolved, which is important for disaster prevention. Using the infrasound signal send from location of the landslide, this work aimed at proposing an advanced 3D matching positioning method, based on ray theory. We first proved vectority of the instantaneous sound pressure field from the perspective of air dynamics, and used ray theory to deduce a point’s instantaneous sound pressure in the air as the sum of all characteristic sound ray vectors. Based on this, the 3D vector acoustic field model was established through simulation. We also found that the triangular pyramid array has vertical and horizontal sampling capabilities, which can collect the vector signals due to the directional anisotropy between the elements. Consequently, the 4-element triangular pyramid vector array was designed to be placed in the acoustic field to receive infrasound signals. Since the infrasound signal is issued before the landslide, we then proposed the 3D matching positioning method: by calculating the cost function of the measurement signal of the triangular pyramid vector array and the copy signals calculated by the propagation model in the predetermined space, point by point, the maximum value was predicted as the infrasound source position, also as the predicted location of landslide. We performed simulations in complex mountainous terrain and applied the method to localization of infrasound sources before the occurrence of the landslide. As a result, by searching and matching in massive space points, we obtained the accurate infrasound source coordinates. This study shows the application prospects of this method for predicting geohazards position several hours in advance.