Hazard Assessment app – excavation view
The grid-based hazard calculations in the Hazard Assessment app were discussed in a previous post. The Iso View describes the hazard at all locations within the mine but when you are considering the seismic risk for a particular work area, large events and strong ground motions may come from multiple sources. The Excavation View estimates […]
Strong ground motion relationship
The strong ground motion (SGM) relationship is used to calculate the peak particle velocity (PPV) generated by a seismic event. You may also hear this referred to as a ground motion prediction equation (GMPE), but only the maximum velocity is estimated, i.e. the strong ground motion, rather than the full, complex wave motion. The PPV […]
What do the hazard iso’s mean?
The Iso View in the Hazard Assessment application expresses the seismic hazard in two ways. The current yearly hazard within the chosen grid volume. This is shown in the footer of the 3D view, as the probability of an event exceeding the design magnitude. The spatial distribution of the hazard. This is highlighted by the […]
Track seismic hazard over Time (per volume)
We have added some new features to the Hazard Assessment app to calculate the minode hazard for filter volumes. This works just like the current minode calculations, where you can select minodes and compute the probability, P, of exceeding your design magnitude, within R of any selected minodes. The volume hazard refers to the seismic […]
To a/b, or not to a/b
The a/b value is sometimes used as a measure of seismic hazard but there are some common mistakes made with this analysis and interpretation. What is a/b? The Gutenberg-Richter distribution is a statistical model that describes a log-linear relationship between the number of events, N, exceeding magnitude, M. log10 N = a – bM At N […]
Frequency-magnitude chart anatomy
When you are using the frequency-magnitude chart, it can be easy to forget it is log scale and this can distort a few things. Consider the chart below; have you ever thought the Gutenberg-Richter distribution doesn’t look right? Think it isn’t matching the large events very well? The Gutenberg-Richter distribution is a statistical model of […]
Event tags and comments
There are many reasons you might want to store a short snippet of text associated with an event. There are two ways to do this in mXrap; event tags and event comments. Event tags can be used to group events into categories. Example tags might be ‘suspected blast’, ‘damage occurred’, ‘suspect location’, ‘outlier’ or ‘likely […]
Using selections in the event filter
You can use selections to filter events in General Analysis. This gives you a lot more freedom than being restricted to the traditional min/max range filters. Follow the steps below to see how you can use this feature to plot the frequency-magnitude chart for events occurring during periods of high apparent stress. You can also […]
New Monitoring/Control Room App
We previously created a Basic Seismic Monitoring app but it didn’t get widely used. We’ve taken another swing at a new version released late in 2017. The new app is intended for mine control room operators to monitor the latest seismicity and communicate event alerts and exclusion areas depending on site specific rules. Each site […]
Seismicity Versus Distance to Surveys – New Charts in General Analysis
The distance to survey filter has been around for a while but now we have added a couple of new charts to further investigate the relationship between seismicity and your input surveys. The charts have been added to the General Analysis application, under the Charts menu – look for Distance to Surveys. There is a […]
