The excavation hazard is calculated on minodes that represent underground tunnels as a series of connected nodes. For more information on minodes and to find out how to create or update them, go to this page: Minode Generator

You can pick any grid cell to view the frequency magnitude chart of events found in the local area. This is the b-value used for this grid point. The b-value is a very sensitive parameter in hazard calculations, and there are cases where the automatic FM modelling algorithm may not work well. There are several markers to help identify potential areas where the FM model may not represent the data accurately:

Grid-based seismic hazard assessment using seismic data for spatial hazard mapping and analysis.

If you pick a minode in the 3D View, the grid point sources that contribute to the hazard at that minode will be plotted, scaled by how much they contribute. Theoretically, every grid point contributes to the hazard at a minode, but there is an accuracy threshold applied with a minimum probability to speed up the calculations. Increasing the accuracy will result in more contributing grid point sources.

Overview

Probabilistic seismic hazard evaluation based on grid and spatial methods.

Event rate calculations and splattering in grid-based hazard assessment.

The hazard assessment app is designed to be simple to use but beneath the interface is a lot of complexity. It is important to be familiar with the underlying calculations and ensure that you are aware of the assumptions and limitations of the analysis. The calculations have been described in the linked pages below.

There are three types of isosurfaces that can be plotted in the Hazard Isosurfaces window. The details behind the calculation of each parameter is linked in the pages below:

Grid Definition

You can now plot the relationship in a couple of different ways:

Hazard can be tracked over time by specifying a number of time steps and a step interval. The back analysis tool will step the backdate backward through time and summarise the hazard within each mining volume. Mining volumes can be defined in the Configuration area (link to filter volume editing page). The hazard within each mining volume is calculated by accumulating the hazard within each grid cell or for each minode within the volume.