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Théorie derrière mXrap

📄️ Energy - moment relationship

Energy and moment are two independent measures of the strength of a seismic event. Their physical meaning and how they are calculated was described in a previous post. Analysis of the relationship between the energy and moment of events can provide insight into seismic sources. For example, blasts or ore pass noise, falsely processed as real events, tend to have distinct zones on an energy-moment chart. In general, events with higher-than-average energy are associated with high relative stress.

📄️ Hazard Assessment - Event Rate

The Hazard Assessment application uses a grid-based approach to describe the seismic hazard throughout your mine. Each grid point essentially represents a seismic source with a specific frequency-magnitude relationship. A frequency-magnitude relationship is defined from the $M$, $Mmin$, $b$-value, and event rate. We've previously delved into $M{UL}$ in this post. We also discussed how $Mmin$ and $b$-value are calculated along with other gridding parameters in this post. The event rate is something we haven't taken a dive into yet, so we'll get into it in this post.

📄️ Stochastic declustering explained

A stochastic declustering algorithm has been implemented in mXrap to separate events into 'clustered' and 'background' components. It can be useful when designing seismic exclusions and re-entry procedures to separate seismicity that occurs in short bursts from seismicity that has low variability in space and time. Short-term exclusions cannot be used to manage the risk associated with background seismicity, since the hazard inside a potential exclusion would be the same as outside the exclusion. Efficient exclusion and re-entry procedures target areas where seismicity is most clustered and where the seismic hazard to which people are exposed can be reduced with a short disruption to production.

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