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 MUL, Mmin, b-value, and event rate. We’ve previously delved into MUL 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. Event rate sounds like a simple calculation but there are quite a few complexities worth explaining here. There are also a couple of controls for event rate hidden away in the Advanced Tools that might be worth investigating at your site. These controls will be explained below too. The event rate refers to the number of events above a certain reference magnitude, usually Mmin. On the frequency-magnitude chart, essentially the b-value is the slope and event rate is the intercept. It is related to the a-value of the Gutenberg-Richter distribution. You might also see the event rate referred to as the lambda (λ) value. This comes from the Poisson distribution where λ is the rate parameter. The event rate parameter refers to a specific time interval and volume. The number of events during the data period is adjusted to refer to one year’s worth of activity. For the hazard calculations, the event rate is associated with the number of events within the 3D cubic volume of the grid cell. However, the event rate that is plotted in 3D with isosurfaces is adjusted to refer to the event rate within a 50 m spherical volume. The standard volume adjustment is done so that you can modify the grid spacing and the event rate will remain the same. Event Splattering Events within the data period are assigned to the grid with a ‘splattering’ process. Just like if you throw a ripe tomato, it might splatter onto the wall, events are splattered onto its nearby grid points. The kernel function controls the distribution of an event onto the grid. Grid cells closer to the event have a higher weighting. A cubic kernel function is used to assign a portion of each event to grid points within a maximum radius, Rmax. The total contribution of a single event to the grid is always normalised to be equal to one. This avoids the problem of overcounting or undercounting events and ending up with an inaccurate grid event count. If you have 1,000 events in the data period, you want the total event count of the grid points to also work out to 1,000. When all events have been splattered, each grid point then has the number of events associated with its cubic volume. The maximum radius, Rmax, of the kernel function is adjusted for each event. Larger magnitude events have a bigger area of influence. The radius is also expanded in lower density areas to reduce the artifacts around the edges of seismic clusters. The Rmax is generally the maximum of the following parameters: 20 m. Minimum Rmax for all events. 1.5 x Grid Spacing. To avoid events missing grid points when grid spacing is large. Event Source Radius. To increase the zone of influence of large events. Distance to the 5th Nearest Event. To smooth areas with sparse event density. These parameters are capped at 100 m so Rmax can’t go higher than that. There is a final smoothing factor applied to Rmax that is a control in the Advanced window. The default smoothing factor is to double the calculated Rmax. The figure below shows the effect of the smoothing factor on event rate at the Tasmania mine. Increasing the smoothing factor generally lowers the peaks and raises the troughs of the event rate distribution throughout the mine. Small Event Weighting Event rate calculations generally use events above the global Mmin. The trouble is this excludes a significant portion of the database and limits the resolution of the seismic hazard assessment. To try and utilise additional data, events just below the global Mmin are also considered. Events below Mmin within a magnitude range, Δ, are splattered onto the grid as an alternate estimation of event rate. Since these events are under recorded, their contribution onto the grid is increased to compensate. The figure below shows how the small event weighting is calculated by estimating the amount of under recording compared to a complete dataset. The two event rate calculations, from events above the global Mmin, and smaller events, are compared and the higher of the two rates is used. The use of smaller events is turned on by default, but you can turn this off in the Advanced window. You can see the difference in the event rate calculations at the Tasmania mine with and without the small events. The differences are small but there is generally more information at the edges of the seismic clusters when small events are used. Using Local Mmin The event rate calculations generally don’t consider the spatial variation in Mmin. However, we have made a recent addition to give you the option of using the local Mmin calculated at each grid point. The same approach is taken, except an event is only splattered onto a grid point if its’ magnitude is above the local Mmin. The small event adjustment still works but the global trend in under recording is used for the small event weightings. The local Mmin option is available in the Advanced window and the results are compared for the Tasmania mine below. The same general trends are there when using local Mmin although it does increase the variability. The differences are more prevalent in areas with lots of data. Concluding remarks Feel free to investigate these event rate controls at your site and consider if they might be of use to you. In general, the differences will be small as the event rate is fairly insensitive to

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Inspections and data entry app

We are excited to announce our new inspections and data entry app. This app is a general purpose data entry app designed for offline use with tablet devices which can be customised to fit each site’s exact needs.The app allows simple and fast input of multiple data types (selection, text, numerical inputs, orientation etc.) as well as attaching photos and sketches to reports. Inputs can be grouped into sections, or into different pages for easier use. The location of inspections can be georeferenced using the mineplans and a polyline system to show where the inspection was done. Data can also be attached to this polyline, to indicate different data in different areas. An example of this is rock mass characterisation mapping, where different sections of drive can be assigned values. The app also allows you to view the data from previous reports. This view can also be saved as a PDF file to use as a report that can be given to management etc. The desktop mXrap side of the app is also completely customisable, and the mXrap team can help you to build exactly what you want to achieve the analysis you need to do. Tables with inspections registers, charts for monthly reports, 3D views to show the underground locations of inspections and even automatically generated reports. Uses of the app so far include:– General underground inspections– Quality Assurance/Quality Control inspection– Rock mass Characterisation mapping– Open Pit Inspections– Pastefill UCS Testing If you want more information or are interested in trying in the app, please get in contact with the mXrap team via info@mxrap.com

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Filter volumes library changes

We have recently updated the JavaScript library mxjs/base/algorithms/filter_volumeset.js to be more efficient. If you are using this library and call the flag_members() method of volume sets directly, then you will need to update your code slightly. If you don’t call flag_members() directly then you’ll automatically get the efficiency updates when you upgrade without needing to do anything, and you can stop reading now 🙂 Previously code would create a finder object from the mxjs/base/algorithms/find_neighbours_3d.js library like so: And then pass it to the flag_members() method: With the updated library you should remove find_neighbours_3d.js and instead create a finder object like so: And then pass this finder object to flag_members() in the same way as above. For the moment the old style is deprecated but will continue to work, so your code will not break, but in the future we will remove support for the old style. If you have any questions about the change, please get in touch with us at support@mxrap.com.

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Export Panel for 3D Views, Charts and Tables

The export panel, located on the right-hand side of 3D views, charts and tables, can be used to generate images, files, and videos with just a couple of clicks. This panel is particularly useful for preparing presentations and papers that require figures with specific dimensions or font sizes. Use the ‘Export dims:’ functions to create high quality images of a specific size: Use the ‘Content:’ options to change what components are shown: Export tables to the clipboard or as a file: Create custom videos of your data, analysis and results: For a more detailed walk through of how to use the export panel, check out the mXrap training video: https://www.mxrap.com/mxvideos/link/22

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mXrap Version 6 – User Change Logs

We’re pleased to announce the release of mXrap version 6, bringing with it a range of enhancements to elevate your mXrap experience. This major update includes improvements to the user interface, as well as enhancements to speed when loading the root folder and applications. Additionally, we’ve upgraded the 3D rendering and navigation capabilities in the 3D views. However, it’s important to note that older root folders may not function properly in version 6 due to incompatibilities. Therefore, it’s crucial that all root folders and apps are upgraded and checked to ensure they work correctly before transitioning. If you haven’t received communication about this upgrade yet, expect an email in the coming weeks with instructions on how to complete the process. Please be aware that mXrap version 5 is scheduled to cease functioning in May 2024. Your cooperation during this transition period is greatly appreciated and will help facilitate a smooth migration to the new version. When you transition to version 6, you’ll need to rebuild your event survey caches. If you require assistance with this or encounter any other issues, please don’t hesitate to contact us at our support email address. For a comprehensive list of changes, please refer to the user change log here: mXrap Version 6.0.0 User Change Log For developers actively working on applications within mXrap, additional information can be found here: mXrap Version 6.0.0 Developer Change Logs We’re excited about the possibilities that version 6 brings and look forward to your continued support and feedback.

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mXrap Version 6 – Developer Change Logs

mXrap version 5 will stop working in May. We will be transitioning everyone to mXrap version 6 before then. As old root folders may not work in version 6 due to incompatibilities, all root folders and apps must be checked to ensure they work in version 6. To avoid any downtime for our users and developers, please check that all root folders are upgraded. For developers who are working on roots that are compatible with version 6, you can find the list of changes from the links provided below.The notable changes that would effect development includes the change in scope for Table Calcs and data structure changes (octal literals, null locations, etc.). These changes mean that some Table Calcs or Row Calcs may break. Please read the change logs on how to address this. Changes for users:https://mxrap.com/changelog/6.0.0/users/ How to migrate your stuff to v6:https://mxrap.com/changelog/6.0.0/migrate/ Changes for app developers:https://mxrap.com/changelog/6.0.0/devs/  If you are still using version 5, please install version 6 from our website.If you have any issues with version 6, please re-install version 5 from our website and contact support to resolve the issue. Please note that if you are working on version 6 and your root is not working, then the root will required a root upgrade.

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Modifying The Blast Record

When trying to add, delete or change blasts in mXrap, best practice is to use the ‘Blasts Editor’ found under the ‘General Set-Up Windows’ tab: If you need to make bulk changes however, it may be tempting to directly alter the input file in the root folder. Problem: When you open the ‘Blasts.csv’ in MS Excel, it automatically changes the date format and mXrap is no longer able to read the blast information. Solution: Prior to saving the new file, format the Date column to match the input required for your root: yyyy-mm-dd hh:mm:ss.0   This is the typical input format, but you may have to modify slightly in order to match the format for your specific root. This can be done by selecting the Date column, right clicking, and opening ‘Format Cells’. Choose the ‘Custom’ category, and manually enter the input format for your root: To see your changes, save the file and ‘Reload Data’ in mXrap.

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Changes to root structure

There has been some rearrangement to the ! folder within the root folder, which may affect some of your apps. This was primarily a move of tools which are not seismic specific from the ! folder to !/Base (so that mines without the seismic suite can use these tools). The most commonly used parts of this migration are anything that uses Filter Volumes, Grid definitions or Plane definitions.Apps that you created that are being used on site will break as a result of these broken connection in upgraded root folders. As we transition to v6 of mXrap, root upgrades will be required, and any of your custom apps will require fixing. To rectify missing sources, you can either manually change links (on an updated root folder) from the old to the new location, or use mXrap’s redirect source/table/column feature in the menu bar of the Settings window: The moves are as follows:!/Filter Volumes -> !/Base/Filter Volumes! Standard Data/File Locations -> !/Base/Standard Data/File Locations Some of ! Standard Data/Parameters -> !/Base/Standard Data/Parameters , including:Filter VolumesGrid DefinitionsPlane DefinitionsImport/Filer Volumes Auto-IDImport/Filer Volumes CSVImport/Filer Volumes StagingImport/Grid Definitions Auto-IDImport/Grid Definitions CSVImport/Grid Definitions StagingImport/Plane Definitions Auto-IDImport/Plane Definitions CSV A summary of the new locations are shown below If you have any further questions, or have issues making these migrations in your apps, please contact the support email address.

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