As mentioned in the last blog post, Energy and Moment are independently calculated based on the displacement and velocity spectra of the recorded waveforms. Another spectral parameter is the corner frequency.
The figure on the left shows the corner frequency (f0) on theoretical displacement, velocity and acceleration spectra. The calculation of corner frequency relies on fitting a reliable source model to the observed spectra.
Many commonly used source parameters are derived from Energy, Moment and Corner Frequency. Below is a quick guide to these parameters, illustrated with an Energy-Moment chart that has events coloured by the relevant parameter.
The corner frequency is indicative of the dimensions of the source (source radius in the case of a circular fault). This is a physical relationship easily demonstrated. In the linked video, you can see and hear the decrease in frequency as the length of the ruler is increased. Another example is the change in frequency resulting from changing the length of vibrating guitar strings. For the same physical reasons, larger seismic events tend to have lower frequencies. The radius of the seismic source is calculated from f0.
In theory, the source volume can be calculated based on the Moment and source radius. In practice however, “Apparent” volume is more commonly used to approximate the source volume. The source volume is proportional to the cube of source radius, therefore any errors in the source radius parameter (or corner frequency) are amplified. The method of calculating Apparent Volume is more stable, based on Energy and Moment.
You know that energy and moment are parameters to describe seismic events. But what exactly is their physical meaning for a seismic event source and how are they calculated?
Moment and energy are both separate (but related) measures of the strength of a seismic event. A similar example is a car engine, the performance is described with two separate (but related) measures: power (hp or kW) and torque (Nm). In a simplified piston and crankshaft arrangement, the torque is the twisting force exerted by the force of the piston on the lever arm (crankshaft). Power relates to the rate at which work is done and how fast the torque is applied (torque x RPM). So, moment, energy and power are all related measures of the system performance.
You might have heard that energy and moment are independent source parameters. This is to distinguish them from derived parameters (parameters that are calculated from energy, moment, corner frequency etc). They are independently calculated but they are not unrelated to one another. Moment is related to the displacement (strain) of the source. Energy is related to the speed at which the displacement happens. In general, higher stress conditions lead to higher rates of displacement and therefore higher energy relative to moment.
What does Moment physically mean?
So, you know that moment is a force applied to a lever arm. You might be wondering, where is the lever arm for a seismic source? In the context of seismic sources, moment is a force couple. Two equal and opposite forces, with a notional distance between them, forms a definite moment.
Let’s look at a force couple applied to a small crack. The images below are displacement results from a simple Phase2 model of a small horizontal and vertical crack. The arrows indicate the direction of the displacement. Notice that the displacement pattern is essentially the same for both force couples. This is why, when you do an inversion from the observed waves trying to model the source, the solution comes down to a double-couple. There is no way to distinguish between the two possible solutions.
The displacement field caused by a dislocation on a plane is fundamentally equivalent to that produced by a double-couple. For a homogeneous and isotropic medium, the moment of a seismic event caused by the shear fracture on a plane is:
M = G x D x A
- G = Shear stiffness of the rock
- D = Average displacement
- A = Area of slip
How is Moment calculated?
We are rarely in a position to be able to measure the area of slip or the amount of displacement. In practice, moment is calculated from seismic waveforms, usually in the far-field (outside the source volume). The Brune model is used to relate the characteristics of the seismic source to the characteristics of the recorded waveform. The model is based on a circular disc (penny) shaped dislocation surface where a tangential stress drop is applied instantaneously, resulting in a shear wave propogating perpendicular to the fault surface.
To compute Moment, a Fourier transform is required to convert the displacement waveform from the time domain to the frequency domain. The frequency content is also referred to as the spectrum of the signal. Moment is proportional to the spectral level (Ω0); the plateau of the displacement spectrum at lower frequencies.
The spectra for each sensor must be corrected for geometric attenuation and decay and the Brune model must be fitted to the signal. Moment can then be computed as:
M0 = 4πρV3Ω0R
- ρ = rock density
- V = the sonic velocity in rock
- R = the distance to the source
In theory, the Brune model is only applicable to the S-wave but in practice, the same method is used for the P-wave. The final Moment for a seismic event is the average of the S-wave and P-wave moment.
M0 = (Mp + Ms)/2
What does Energy physically mean?
While seismic moment is a better description of the intensity of a seismic event within the near-field, seismic energy is a better description of the potential damage outside the source volume. The energy source parameter does not represent the total work done during the event, rather the energy that is radiated away from the source. The elastic energy radiated by a seismic event is only a fraction of the total work done by the source.
How is Energy calculated?
Similarly to moment, energy is calculated in the frequency domain, except energy uses the velocity spectrum rather than displacement. The radiated energy is proportional to the velocity-squared spectrum integrated across the full frequency domain. The total energy for a seismic event is the sum of the P-wave and S-wave energy.
E = Ep + Es
The calculations for seismic energy and moment are complex and there are several assumptions and sources of error such as:
- Error associated with integrating recorded wave to displacement in the time domain
- Assumptions associated with the Brune source model
- Error associated with fitting the Brune model to the displacement and velocity spectra, including when bandwidth limitations of seismic systems result in a poorly constrained fit
- Error associated with the calculation of source location (R)
Did you know you can download root folders from mXsync? We have uploaded root folders for Tasmania and Big Bell mines. These sites have closed and the data has been made available for research. Have a look at the “Download a component” training video for a guide to downloading these roots onto your computer. The data can be handy for research projects or just for curiosity’s sake. You may even want to download the Xgames root…. for work purposes of course.
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 hazard for minodes within the filter volume. The same backdate, backrange, Mdesign and R parameters apply as the existing tools.
Another tool has been added to track the volume hazard over time. Essentially this repeats the volume hazard calculations, stepping the backdate through time and plotting the hazard per volume. Refer to the “Track Volume Hazard” training video for a walkthrough of the new tools in the hazard app.
We will need to upgrade your root before you can use the new tools. If you would like us to upgrade, drop an email to firstname.lastname@example.org. Root upgrades are fairly quick but you will need to give us access via Teamviewer, Webex or similar.
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.
The seismic hazard in the chart below can be considered in the following way. For a given time span and volume, if N events have been recorded, what is the probability that one of those events was above Mdesign? In this case Mdesign = ML2.
Seismic hazard increases with increasing N and decreasing b-value. Note on the chart, N = 1,000 and b = 0.9 gives the same seismic hazard as N = 10,000 and b = 1.2 (approx). In other words an increase of 0.3 in b means you need 10 times more events for an equivalent hazard.
So, seismic hazard is very sensitive to the b-value of the area. This is important to consider when looking at daily activity rates. In some areas, 100 events may represent a very different hazard to 100 events in another area if the b-value varies.
Another point of interest in the chart is that for areas with b-values above 2, even very high event numbers represent low hazard.
Yes, this is a frequently asked question…. MUL or MUpper-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 MUL or the Upper-Limit Magnitude, this will clear up the terminology a little.
A quick review on the terminology that concerns the Frequency-Magnitude chart and the Gutenberg-Richter distribution:
- Mmin – The magnitude of completeness, the dataset is considered complete above this magnitude (property of the data)
- b-value – The slope of the Gutenberg-Richter distribution, describes how the frequency of events scales with magnitude (property of the statistical model)
- Xmax – The largest magnitude event in the dataset (property of the data)
- a/b – The magnitude at N = 1 of the GR distribution (property of the model, maximum likelihood, see previous blog post)
- max(m,n) – This is the probability density function, given n events, of the largest event in that n events. This is a property of the GR statistical model. In other words, given a certain GR model, if you record N events, what is the largest event? This is not a single number but a likelihood distribution. The maximum likelihood of the largest event is the a/b value.
- MUL – The Upper-Limit Magnitude of the max(m,n) distribution. It is an estimate only and a property of the statistical model.
The truncating magnitude has slightly different meanings in mining seismology and crustal seismology. MUL is usually referred to as Mmax in crustal seismology literature and is generally considered constant for a particular area. In mining seismology MUL generally increases over time given the gradual increase in mining dimensions and loading of the rock mass. For this reason the definition is slightly modified in mining seismology to be the upper limit of the next largest event.
Why do we need an upper-limit or truncating magnitude?
The truncated Gutenberg-Richter distribution, rather than the open-ended distribution, is the most common frequency-magnitude relationship used in mine seismology. If there is no upper limit given to the GR distribution, then to evaluate the total energy of events in the relevant time period, the energy tends to infinity as the relationship is integrated above Mmin. This is clearly unrealistic.
We know there is a physical limit to possible magnitudes since the size of large earthquakes is related to the slip area of the fault and the physical size of faults is limited. Earthquakes on Earth above magnitude 10 (Richter) are essentially impossible given the size of known faults and a magnitude above 12 represents a fault area larger than the Earth itself!
So it is safe to say that MUL for a particular mine is going to be less than Richter Magnitude 10. The question is how much less is reasonable given the significantly reduced physical dimensions in mining.
How do we estimate MUL?
An empirical method of estimating MUL can be taken using a dataset compiled by McGarr et al. (2002) of large events and the largest dimension of the human activity associated with them. The figure on the right comes from Wesseloo (2018) who added a few extra points to the dataset from Australian and Canadian mines. The range applicable to mining indicates rough dimensions between 500 and 5,000m.
Aside from the empirical approach, there are also statistical approaches to estimating MUL. These generally take the form:
MUL ≈ Xmax + Δ
There are a number of different methods for calculating the Δ value. Many of these methods are described by Kijko and Singh (2011). Most of these have been implemented in the Hazard Assessment app along with the associated uncertainty of each method as described by Lasocki and Urban (2011).
It is better to over-estimate MUL than to under-estimate it. In terms of probabilistic seismic hazard calculations, the truncated GR model will always give a lower hazard result than the original GR, for magnitudes approaching MUL. For magnitudes well below MUL, the seismic hazard calculations are the same. In the Hazard Assessment app, we take the maximum of each MUL + σ estimate from multiple methods.
These statistical approaches assume the recorded magnitudes of large events are reliable. Moment is under-recorded for large events if there are no low-frequency sensors installed. The figure to the left comes from Morkel and Wesseloo (2017) showing the effect on the frequency-magnitude relationship, given certain sensor bandwidth limitations.
In cases like this it is best to override the MUL as it is likely to be under-estimated with statistical methods.
While it is important to understand what MUL is and how it effects seismic hazard calculations, it is not something to use for design purposes or to communicate seismic hazard. It is just one part of how seismic hazard is defined. By definition, the probability of an event exceeding MUL is zero, so it isn’t a great measure of seismic hazard.
If you have any questions regarding this topic, or something to add, feel free to leave a comment or send an email to support.
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.
We have made a new page for the Training Programme under the Training tab. The programme is structured in several user levels, from a basic introduction to General Analysis, moving through all the apps and finally to advanced app building tutorials. There are a few links to relevant blog posts and papers that will help users understand some of the analysis concepts. There are also exercise questions in each section for users to complete using their own data.
Charts usually auto-adjust their ranges to the input data. This is often what you want, but occasionally it does make it harder to compare charts with different filters applied. A handy tip is to enable the “Zoom and Pan” option in the top-left. This disables the auto-zoom and pan so then if you change the filter, you can compare the two charts. An example below is the FM chart for all events, compared with the events for just the last month. Enabling the Zoom and Pan means the axes remain the same for both charts.
You can also zoom and pan to a different area. Remember if you scroll the mouse in the chart itself, it zooms both axes together. You can zoom a single axis independently by scrolling on the axis label area.
Most users are probably aware of the Quick Reference Guide in the Cheat Sheets. It lists all the mXrap shortcuts and hotkeys but it is spread over a few pages and can be a bit tough to find what you’re looking for. Below is a one-page Quick Reference Guide for more of a visual lookup of the main controls. The controls for the new Annotations tool are not included but help for those controls is available in mXrap itself. Here is the PDF version of the one-page guide if you want to print a copy.
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 = 1, M = a/b. The figure below shows an example of a frequency-magnitude chart with the a/b value highlighted.
Does a/b mean anything?
It is important to distinguish between properties of the dataset and properties of the statistical model. The a/b value is a property of the Gutenberg-Richter statistical model but it is defined at a particular data point (N = 1). The a/b value does have some meaning, but that’s really only because the a and b value both mean something (although I’ll come back to the a-value later). In terms of seismic hazard, the activity rate and b-value are the two primary inputs required.
The focus on the magnitude where N = 1 is somewhat arbitrary. The statistical model describes the relative frequency for all magnitudes. It is just as valid to normalise the frequency axis to a percentage i.e. express N as a percentage of the number of events at M = Mmin. So in the figure below, at Mmin, the frequency is 100% and events over M = 1 represent 0.1% of all events over Mmin. Note the a/b magnitude represents approx 0.006% of events. So the magnitude at N = 1 loses its significance. Asking what is the significance of a/b is like asking the significance of the magnitude of the top 0.1% of events? Why not the top 0.01% or 0.001%?
The normalisation trap (or the non-normalisation trap)
The reason the a/b value doesn’t mean much for seismic hazard is because the a-value by itself is meaningless. The number of events, by itself, doesn’t tell you anything about hazard because it has no associated time and space units. It should be pretty easy to understand the importance of normalisation to regular time and space units. If I tell you there has been 100 events, you don’t know anything about what seismic hazard that represents. It could be 100 events in a very small volume, in a very small time period; this would be a high hazard. It could be 100 events in a very large volume over a very long time period; this would be a low hazard. So the important thing for seismic hazard estimates is the event rate density, i.e. the number of events, per unit time, per unit volume. Only then can you compare apples with apples.
One final point. A constant event rate density, and a constant b-value over time represents a constant hazard state. The problem is that the a/b value without normalisation is entirely dependent on how long you have recorded this constant hazard state. The total number of events (i.e. the a-value) continuously grows and so does the a/b value, even though the hazard state is not changing. This is why without normalisation, the a/b is not a measure of hazard.
If you normalise the event count based on the event rate density and a standard time and volume, the a/b value can be a measure of hazard. However, in terms of probabilistic seismic hazard, the probability that the largest event in the database will exceed the a/b value is ≈ 63%, assuming an open-ended Gutenberg-Richter distribution or a very high MUL (MUL >> a/b).
- The a/b value is a property of the Gutenberg-Richter model, not of the dataset
- There is no special significance to the magnitude where the Gutenberg-Richter model crosses N = 1
- The a/b value is a function of the number of events
- Without space and time information, the a/b value (and the a-value) are not indicative of hazard
- When comparing different times and zones using a/b, you must normalise using the event rate density and a standard time and volume
- The probability of the largest event exceeding a/b is ≈ 63%
You can now measure distances in any 3D view in mXrap (version 5.6.0 or later) with the ruler tool in the Annotations tab. The “Annotations tool” training video on the General and FAQ page goes through all the features and the operation. Most operations will probably be for the distance between two points, such as the event-to-survey distance below. You can also extend this to a multi-point ruler for measuring more complicated paths.
The controls are very similar to selection boxes. Control instructions are in the Annotations tab.
- Ctrl + Left-click to move/select point
- Ctrl + Right-click to rotate/cancel
- Space to insert a point
- Del to delete point
Other features include:
- Snap ruler to point or surface (crosshairs will turn from red to green when snapping)
- Point rounding – For selecting points on a grid or post-rounding
- User defined labels on vertices or segments
- Table of point coordinates, segment lengths, horizontal and vertical runs, trend and plunge
- Optional arrow head
- Save and load rulers
- Flatten points to the focal plane (view plane)
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.
The 3D Controls button has also been moved above the series window and the buttons in general have had some styling. We are planning some further changes to Clipping and looking at combining the dynamic clipping controls with the Clipping panel.
The eXport panel is where you can control the screen capturing and table exports. This tab can be “popped-out” to make it easier to export many tools at once. Please note the “eXport panel” training video has been updated on the General and FAQ page.
If you have updated your software to 5.4.0 or higher, you may have noticed some changes to the Survey Import tool. The Survey Setup training video has been updated on the General and FAQ page. The main changes have been to support additional properties from DXF files.
Text objects from DXF files can now be imported into mXrap and displayed in the 3D view. mXrap version 5.5.2 supports TEXT, ATEXT and MTEXT objects. Be aware that there are limits on the maximum number of texts that can be displayed and MTEXT (multi-line) objects will be converted to one line.
Below is an example of DXT text shown in the Monitoring application, in this case it can be handy for the control room operator to see where the exclusion areas are. You should start seeing more text series in 3D views, where you can adjust the size of the text and set to always face the 3D camera during rotation. This may include event magnitude labels, sensor ID’s etc.
For basic site surveys, you may want to separate your text files from your regular surfaces and lines content so you can turn them on/off independently. Otherwise when you tick a file from the list, all surface, line and text will be displayed together. You can control whether each survey displays its Surface, Line or Text content from the survey import tool.
The colours from DXF files can now be used in mXrap and this option will be enabled by default when you build the cache.
BE AWARE that the DXF colours may not suit the mXrap 3D view. Most mining software packages have a dark background and so DXF colours are often light. These colours may not work so well on the white background in mXrap. This is especially true for lines. White floor strings are quite common and will be invisible in mXrap. There are some auto-correct functions built into the DXF colours for this reason. You also still have the option to override the colour displayed as before.
mXrap supports the following survey formats to be used in 3D views:
- DXF (AutoCAD .dxf)
- DTM / STR (Surpac .dtm/.str)
- PNT (.pnt)
- INP (Map3D Geometry .inp files)
Regarding DXF files, this is a complicated format that AutoCAD often updates with new specifications. Our importer will always be behind the latest updates and therefore incompatible with loading in the very newest DXF formats. When exporting your survey files, you should have compatibility options for older formats. Look for ASCII DXF options R14 or 2000, these will work in mXrap, otherwise it needs a bit of trial and error initially. Binary DXF files are not supported. The other option is to use the Teigha File Converter. It is free to download and use to convert DWG and DXF files into other formats.
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 the data. Consider what the chart looks like in linear scale rather than log scale. The difference at the tail of the distribution (largest events) seems much less significant right? The other interesting point is the relative proportion of events above and below the Mmin. There is roughly only 20% of events in you database that are above the magnitude of completeness.
Obviously in linear scale, you can’t see what’s happening at the tail very well, that’s why we use the log scale in the first place :)
If you were wondering what a bored Xman does in their free time, this might give you an indication…..
You should know by now that mXrap is very flexible and apps can be developed to perform a very wide range of functions. If you were doubting that, this might change your mind :)
Ever played the puzzle game known as 2048? Well now there is an mXrap version!
The mXrap version has buttons for each of the four moves ( Up, Down, Left, Right ) which controls the game board in the 3D view.
If 2048 is not your cup of tea, how about a spot of Backgammon? This is two player and each player rolls the dice and selects where to go from the list of possible moves.
Both of these games were built using the Beta version of mXrap so we can’t send them to you just yet. Once the Beta version is stable we’ll upload the games to mXsync for you to play around with. It will be good motivation for you to learn mXsync :).
Some things you see in mXrap are properties of the software, while other things are properties of the root folder.
We often use the software Excel as an analogy. Excel has many built-in capabilities with endless possibilities for creating specific calculations. The software has powerful capabilities, but without a user constructing the spreadsheet, the power and value are not fully utilised. An Excel user can set up a spreadsheet which, with the required inputs, will provide you with results. This user can then provide you with that spreadsheet, which you can then use to perform the same calculations with other inputs.
mXrap is like the software Excel that provides the basic tools and the applications are like spreadsheets that can be used to perform specific tasks. Anybody with enough understanding of the software can build their own app which can be shared with others.
For example, when you make a chart in Excel, the “add chart function” is a property of Excel. What’s in the chart, what’s on each axis, what colour are the lines etc are properties of the spreadsheet.
mXrap is the same, there is an “Add Chart” function. Every chart in mXrap uses the same tool, but the application configures what’s actually displayed in the chart.
mXrap software level changes are things that affect the “Add Chart” function itself. For example the current mXrap charts only plot data on four axes; top, bottom, left and right. If we were to add more possible axes, like a secondary left axis, this would require a change to the software. It isn’t related to the root folder. Another example is the image capturing tool. This is a feature of every chart, 3D view and table at the software level.
If you want an updated Hazard Assessment application, this is like getting an updated spreadsheet. The root folder is essentially a library of data and applications, like a folder full of different spreadsheets and their associated data.
To summarise, if it seems like its a common feature across many areas in mXrap, its probably a property of the mXrap software. If it seems to be something related to a specific app or chart etc, it’s probably a setting in the root folder.
Updating the mXrap software is easy, just download the installer from the website.
Updating the root folder is what we use mXsync for and it’s actually more complicated to manage the root folder than the software. A bit like trying to manage a lot of interconnected spreadsheets. We normally rely on sites to request root updates. If you read about a feature on the blog or watch a training video that seems different to your current version. You probably need a root update. It’s a fairly quick process, we just need a brief connection with teamviewer / webex or goto meeting to perform the update. Contact us at email@example.com.
If you notice that you are not getting updated events in mXrap, there are a few possible explanations. In order to troubleshoot the problem, it is good to know exactly how your events are transferred from your seismic database, into mXrap.
The first thing to check is if the events are just being filtered out. In the events table, there is a “Show All Rows” option that will disable all filters and show you every event in the database. Sort by descending time and “Reload Data” and check the latest event time. Cross-check with your seismic processing software to confirm you are definitely missing events. Remember there is a short delay (~ 5 mins) from events being recorded to appearing in mXrap.
If showing all rows unveils your missing events, it’s a filtering issue. Look through the event filters to make sure everything is turned off. It might also be the quality filter. To see what quality settings are applied at your site, refer to the “Event Quality Settings” video here.
If you have confirmed the events are not updating, go to your root folder and open the #Events Import folder. Inside there will be an all_events and a recent_events evp file (exact folder, name, extension varies slightly between sites). These are the event files that are read by mXrap. Check the time-stamp of the recent_events file, it normally updates within 5 minutes of the latest event recorded. Try opening the file using notepad, it will be sorted by time so check what the latest event is.
If the EVP files in the root folder have the updated events, mXrap is not reading the files correctly. Contact firstname.lastname@example.org for assistance.
EVP files are generated by querying the seismic event database. The recent_events evp is normally updated every 5 minutes and contains the events from the start of the previous month, up to the present. The all_events evp is normally updated every 24 hours and contains all events up until the start of the current month. So there is always up to one month of overlapping events between the all_events and recent_events EVP’s. The EVP file only changes if there is something to change, i.e. the all_events EVP may be checked for updates every 24 hours, but the file may not have any changes for several days or weeks if none of the processing has changed.
If the evp files in the root folder have not been updated, the problem lies in how these files are copied into the root folder from your seismic database. This process varies by site, depending on whether you use IMS or ESG as your seismic service provider.
IMS generate the all_events and recent_events EVP files and normally store them on the seismic server share drive (often a Linux samba drive). Hitting “Reload Data” in mXrap will copy those EVP files (if they’ve changed) into the #Events Import folder in the root. You need to specify the location of the EVP files on the network. This setting is in the “Config Events Import” app, usually at the top of the app list (log in as Admin or Super User). In this app you should see the file paths to the all_events and recent_events files.
Make sure these file paths are correct and try navigating to the files in windows explorer. If you can’t access the files through windows explorer, you will need to ask your IT department for help to get access to the network location. There might also be a password required.
If you are able to access the EVP files on the seismic server, again, check the timestamps and open the recent_events file to see what the latest event is. If these files are up-to-date, it is a problem with the copy-action from the seismic server to the root. Double check the file path in mXrap is correct and try to “Reload Data” again. Contact email@example.com for assistance if mXrap events are still not updated.
If the EVP files on the seismic server are not updated, it is a problem with the IMS query and you will need to contact IMS for assistance.
We have a purpose built program for querying the ESG seismic database and dumping the EVP files into the root folder. The mXrap Export ESG program normally runs on the ESG computer. Check that this is still running. There should be an icon in the system tray. The ESG Exporter needs to know the location of the seismic database .mdb file and the location of the #Events Import folder in the root. Try manually running the query from the Exporter window and look for error messages and report to firstname.lastname@example.org. Common problems are not being able to write files in the root folder (user permissions), ESG Exporter is out-of-date, or the seismic database .mdb has moved or changed format.
The flowchart below summarises the troubleshooting process when your events are not updating in mXrap (PDF version).
If you are interested in learning a bit more about the structure of mXrap that underlies the main application windows, we have uploaded a series of videos that are a great place to start.
1. The first three videos introduce the root folder and discuss the Settings and Analysis windows where new tools are created and configured.
1.1. Introduction to the Root Folder
1.2. Introduction to the Settings Window
1.3. Introduction to the Analysis Window
2. This next series show you how to create your own Apparent Stress range filter for Events and add it to General Analysis
2.1. Create New Variables
2.2. Create New Range Filter
2.3. Add New Events Range Filter
2.4. Add Variables to General Analysis
3. Create your own Event marker style for Corner Frequency
3.1. Create New Marker Style
3.2. Add New Event Marker Style
4. Import data into mXrap and plot in a new 3D View and Chart
4.1. Import Data
4.2. Create New 3D View
4.3. Create New Chart
5. How to add your own tools to the General Analysis application
For those feeling extra adventurous, we have also uploaded some app building tutorials.
Feel free to contact email@example.com for assistance.
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 crusher noise”. These tags can be used in event filters to quickly show or hide particular categories.
Event comments are a second option to assign user text to events. Each event comment can be unique and about anything. They have no effect on event filters.
You can find videos on “Event tags” and “Event comments” at the training video page below. Both event tags and comments are shown in the main events table in General Analysis.
The event tags system has been modified recently. If your mXrap looks different to the video, you might need a root update. This process is now quick and easy with mXsync. We just need 5-10 minutes to connect via teamviewer / webex / gotomeeting.
Contact firstname.lastname@example.org for assistance.
In early versions of MS-RAP the “Omori” chart included the cumulative energy as a function of time after blasting. You won’t find that line anymore in the default Omori Analysis Tools application.
Although the total energy released has a value, the shape of the cumulative Energy graph inherently has no meaning. The accumulation of a logarithmic parameter is dominated by the largest events and results in a curve with a somewhat arbitrary, random shape. The total energy released is included in the blast table in the Omori Analysis Tools app but the cumulative energy line has no diagnostic value (in fact could be misleading) and does not represent the underlying stochastic process.
To illustrate further, the video below shows a repeated generation of synthetic seismic data where each sample has the same number of events, the same b-value, and the same Omori relationship.
You can capture or save any 3D view, chart or table using the “Clip” or “File” options at the top-right of the mXrap window. There are additional image capturing controls available to increase the quality and to adjust what is captured in the image. For capturing charts for example, you can turn on/off the header/footer, axis titles, axis ticks or grid lines. In table views, you can capture as an image or csv file, all rows or selected, with or without column headers. High quality images can be really handy for reports, papers or website publishing.
People often notice that the local magnitude of an event in mXrap is different from the magnitude shown in their other seismic software. This is usually because the local magnitude equations do not match.
Local magnitude is a calculated (derived) parameter. Normally its either based on Seismic Energy, Moment/Potency, or a combination of both. You should be able to find the relevant details for your site local magnitude in your seismic waveform processing software (eg WaveVis, Trace), otherwise contact your seismic service provider.
In mXrap, local magnitude can be imported along with the other event details from your seismic service provider although this does have low precision which can effect some of the charts and calculations. The reason for the “stepping” sometimes seen in the frequency-magnitude chart is due to an imported local magnitude of only 1dp precision.
The limited precision is why we usually recalculate the local magnitude from the source parameters according to the following equation.
ML = CE x log10(Energy) + CM x log10(Moment) + C
CE, CM and C are the input parameters required. The most common local magnitude scales are below.
CE = 0, CM = 2/3, C = -6 (Moment magnitude, Hanks Kanamori)
CE = 0.272, CM = 0.392, C = -4.63 (IMS scale)
ESG have a few other local magnitude options depending on whether they use uniaxial and/or triaxial sensors. These settings are in the ESG Events Import app. The other settings for local magnitude are in the General Setup app under the Magnitude tab. The “Local magnitude settings” video on this page runs through how to change these settings in mXrap.
Contact us at email@example.com for assistance.
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 check out this page to watch the “Selection boxes” and “How to use selections in the base filter” videos.
Step 1 – Create a new selection on the Apparent Stress Time History chart. Note that selections can be made in any 3D view, chart or table in a similar way.
Step 2 – To apply the selected events to the filter, go to the Events Ranges panel, hit “Copy selections to Base filter” and switch on the selection filter below. Now only the selected events will be used in the Frequency-Magnitude chart.
Step 3 – To turn off the blue selection icons, go to the Events series and turn off the “Highlight selected” option.
Note that if you adjust the selection box or make another selection, you need to hit the “Copy selections” button again to apply the changes. Use the switch to turn off the selection filter and return to original filter.
In the case of the Apparent Stress Time History chart, selection boxes are applied to the frequency line rather than the events in the background. The series that is active for selection can be modified. Look for the “Select” option in the series controls on the right-hand panel.
Did you know that any 3D survey or surface can be displayed in Solid or Wireframe mode?
Hit “W” in the 3D view to switch to wireframes, hit “S” to switch back to solids!
Remember there is a Quick Reference guide in the cheat sheets for all the shortcuts in mXrap.
By now most of you have probably heard of mXsync. It has been installed at all the current sponsor sites and we did explain briefly as we went but there might still be some uncertainty about it.
mXsync is a piece of software installed separately to mXrap that facilitates the backup, restore and upgrading of the site root folder. We hope this new root folder management system will allow new and improved apps to flow more easily and more quickly to sites.
Right now we would like at least one person at each site to get to the point where they have mXsync setup on their computer and they are familiar with how to perform a backup. We’ve uploaded a video that gives a quick intro into mXsync and how to do a default backup. There are a few other videos on mXsync that show you some more operations that sites may need to do at some point.
For a few more details on mXsync, and some things that might be of importance for IT, please refer to the About mXsync page.
Please contact us at firstname.lastname@example.org if you have any problems.
There are a number of quality filters applied to the event database before they are displayed in mXrap. This does sometimes cause confusion because a particular event is visible in your other software, but not in mXrap.
The most common cause is the location filter but there may be other reasons. Have a look at the “Event quality settings” video at the page below. It goes through all the quality filters applied at your site and how to change them.
As always, email email@example.com for assistance.
The default event local magnitude marker might not suit everyone. After all, a ML+1.0 might mean something completely different to you compared with the site next door.
The “Change event marker style” video at the page below will run you through how to make a site specific event marker. There are a couple of other marker styles you can adjust too :)
If the video isn’t clear, please contact firstname.lastname@example.org.
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 can setup their own event alert and exclusion settings in the Basic Seismic Monitoring (Admin) application and then the main application is a simplified interface for the viewer.
Key features include:
- Automatic events updating (no need to keep pressing “Reload Data”!).
- Popup event alert notifications (to alert user when window is hidden/minimised).
- Popup system alert notifications (triggered from threshold time without new events).
- Plot exclusion areas and isolate single mine areas (e.g. single level plans).
- Automatic View – quick zoom/rotate to the exclusion areas on screen.
- Distance measurement – get the distance from any survey point to the nearest event alert.
There are two videos uploaded at the page below; one to show you how to do the initial setup in the Admin window and another for the basic user in the main monitoring window. If your root looks different to the video, you might need a root update. The process is quick! Just contact support.
We are also working on a few more features for the app and will hopefully release another update soon in 2018. Additions should include:
- 3D text from DXFs
- Non-spherical exclusions (cylinder or box)
- Alternate event marker style
- Improved data reload speed
- Popup event query window (for source parameters)
- Enable/disable auto-clipping
- Event comments included in the table
If you have any questions or comments, feel free to email email@example.com.
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 training video to explain a few things about the charts, find it here: https://mxrap.com/training-videos/dist-surveys/
The example below shows how you can compare your seismicity around your geological structures. Of course, sometimes a structure will have a lot of seismicity nearby because you happen to do a lot of blasting nearby. You can also plot blasts as a function of distance to survey!
If you can’t see the charts in your mXrap, you might need a quick root update, ping us an email at firstname.lastname@example.org and we’ll sort it out. Now we’ve setup everyone with mXsync, updates are very easy, will probably only take 10 minutes on teamviewer/webex :)
What do you think of the new charts? Any ideas for additions or improvements? Contact support and let us know!
If you want to learn more about mXrap, we don’t have a user manual to read. Who would want to read through one of those! We have been writing “cheat sheets” to show new users the main features of mXrap.
We’re still going to try and keep the cheat sheets updated, but we are going to focus more on our new training videos platform!
This is where we will post short tutorial videos to show and tell all the features of mXrap. Things like modifying clipping volumes, calculating hazards, using the gridding app will all be included. In time we will add more FAQ content and even some more advanced training material for those who want to play around with the guts of mXrap.
There is a link to the training videos from the mxrap.com website, look for the training tab. This is the direct address: https://mxrap.com/training-videos/
The training videos are password protected, ping us a quick email at email@example.com and we’ll send you the password. Please don’t share the training videos outside of the mXrap sponsor network.