The isosurfaces for b-value have been upgraded in the latest root. There is now much more control over the isosurface levels. Up to 5 iso's can be plotted for user defined ranges.

The root upgrade that coincides with the software upgrade beyond v5.9 includes a new app for creating and exporting models of mine geometry. Stope, cave and development geometry is a fundamental aspect of most geotechnical analysis. Mine geometry also varies over time and capturing these changes is critical in any back analysis or numerical modelling that investigates stability or monitoring parameters over time.

We have started rolling out a new version of the mXrap software and root folder. Software versions 5.9 and above include a few interface changes. The new version is available on the download site but DO NOT download it until someone from the mXrap team has upgraded your root folder. Several root folder changes need to be made simultaneously with the software upgrade. We will be in touch soon to arrange the upgrade (if we haven't already).

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 the seismic hazard associated with working areas (minode locations) in a few different ways as described below.

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.

Probabilistic seismic hazard calculations are dependent on the number of events (N) and the b-value. But which has more effect on the hazard result? The chart below shows how seismic hazard varies with b-value for N = 1,000, N = 10,000 and N = 100,000.

Yes, this is a frequently asked question.... $M_{UL}$ or $M_{Upper-Limit}$ refers to the truncating magnitude of the Gutenberg-Richter distribution. We used to refer to this as Mmax in the Hazard Assessment app and on the frequency-magnitude chart but we found there was confusion caused by Mmax being used to describe multiple things. Hopefully if we refer to $M_{UL}$ or the upper-limit magnitude, this will clear up the terminology a little.

We started making training videos about 12 months ago and feedback has been quite positive. At the last AGM, a suggestion came for a training programme aimed at new users to mXrap. The training videos are currently stored by app but a specific programme would help new users with a logical order for progressing through the training content.

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.

There have been some interface changes made to the mXrap software in versions 5.6.6 or later. The right-hand-side controls have had a bit of a face-lift and now there are separate coloured tabs for exporting, selections, annotations and clipping.