A new method for determination of a wave-ray trace based on tsunami isochrones
A new method for the tsunami wave ray construction is proposed. It is based on isochrones that are built with the use of the wave travel times to a tsunami source. The wave ray approximation is determined as a broken line passing through intersection points of identical time isochrones from two supplementary dot sources. The method was tested on different types of the bottom relief. 1. Methods for the wave ray construction There are a few different methods for the wave rays determination in a non-homogeneous area. The first way is constructing a ray by a numerical solution to the differential equations [1]
Directivity of tsunami generated by subduction zone sources
In a subduction zone, a tsunami source is usually situated above the continental bottom slope. Due to the wave refraction, the opposite slope of a deep water trench works like an optical lens for tsunami waves. The tsunami propagation process is studied using the wave-ray approximation. The tsunami amplitude reduc- tion rate strongly depends on a relative (regarding a trench) location of the initial surface displacement. If the source boundary expands closer to a deep trench axis, then the initially circled front line of the leading tsunami wave will be formed into almost a at shape after passing a trench. The same kind of tsunami behavior can be observed when a wave is generated by a submarine mudslide on a trench slope. A number of hypothetic tsunamis were simulated in the Alaska-Aleutian and in the Kuril{Kamchatka subduction zones. Some locations of possible tsunami sources are estimated as most dangerous for the Hawaiian population and infrastructure. For the most part the tsunamigenic earthquakes occur at subduction zones. The presence of a deep water trench is the main characteristic feature of such a zone. The initial ocean surface displacement (a tsunami source) and earthquake epicenters are mainly located above the continental bottom slope. In Figure 1, the bottom relief (1) of the Kuril{Kamchatka region with historical tsunami source locations is presented (2). The depth at the deep water trench axis is approximately twice as great as an average depth of the Pacic
Research on Fracture Recognition in Well Logging Images: Adversarial Learning with Attention
Semantic recognition of fractures in well logging images is vital for engineers to implement oil and gas exploration. An essential approach to accomplishing the object is to adopt deep learning based on convolutional neural networks. However, due to the lack of annotated labels in well logging images, it is scarcely available to directly train the semantic segmentation network. In this paper, we explore a domain shift model attempting to achieve domain adaptation from one annotated dataset to our target well logging images. This model's core is to utilize adversarial learning, including generator and discriminator, which can prompt the model to generate fracture segmentation similar to the source domain in the target domain. For enhancing the domain adaptive model further, an attention module is introduced, which can suppress redundant noise in semantic segmentation results. We demonstrate that our proposed model performs well by extensive tests and ablation experiments in the ultrasonic well logging images.