Blast Vibration Monitoring in Mining: Limits and Steps

Blast vibration monitoring means placing a seismograph at the nearest house or structure, recording the peak particle velocity (PPV, the fastest ground speed in mm/s or in/s) and the airblast of every blast, and checking both against a written limit. The limit depends on where you mine. For surface coal mines in the United States, federal rules cap PPV at 1.25, 1.00 or 0.75 in/s depending on distance (30 CFR 816.67). In New South Wales, mines typically work to 5 mm/s, with up to 5% of blasts allowed to reach 10 mm/s in a year (NSW Minerals Council). This guide gives the limits side by side, a step-by-step control plan, the seismograph setup rules, a scaled-distance calculator for the charge you can fire per delay, and the drill and blast data worth keeping.

The page is written for mine managers, blasting engineers, environmental officers and small licence holders who need a vibration control plan that regulators and neighbours will accept. It is general information, not a blast design. Blasting must be designed and fired by a licensed blaster under the rules of your regulator.

What blast vibration monitoring measures

Every blast sends two waves out from the pit. Ground vibration travels through the rock and soil, and it arrives first. Overpressure, also called airblast, travels through the air and can shake windows and walls (NSW Minerals Council fact sheet). A monitoring station records both.

• Peak particle velocity (PPV): how fast a particle of ground moves at its fastest, in mm/s or in/s. One inch per second is 25.4 mm/s. A blast monitor records it along three axes at right angles, and rules usually apply to the largest of the three (30 CFR 816.67 applies the limit to each axis).
• Frequency: how many times per second the ground shakes (Hz). Houses respond more to low-frequency shaking, so some limits, such as the USBM criteria, fall as frequency falls.
• Airblast: the pressure pulse in the air, in decibels (dB). Linear peak (dB Lin Peak) means no filter is applied to the measurement.
• Charge per delay: the weight of explosive that fires in one short time slot. It is the main lever you control. The NSW fact sheet calls the largest amount per delay the maximum instantaneous charge (MIC).
• Burden and spacing: the distance from a hole to the open rock face (burden) and between holes (spacing). Both set how well the rock breaks and how much energy escapes as vibration.

The monitor does not prevent vibration. It proves what a blast produced at a defined point, and it gives you the data to tune the next blast.

Blast vibration limits compared

There is no single limit worldwide. Some limits aim to prevent damage to houses, and others aim to prevent complaints. Read the basis before you copy a number into a plan.

Chart

Ground-vibration limits at homes, converted to mm/s

Selected rules and criteria; 1 in/s = 25.4 mm/s, rounded to 0.1

The Australian figures protect people from alarm, so they sit far below damage levels. The NSW EPA’s industrial noise policy leaves blasting out and points mining and quarrying proposals to the 1990 ANZECC guideline (NSW EPA), which the NSW Planning Portal describes as setting comfort criteria for airblast, ground vibration, blasting times and blasting frequency at residences, hospitals and schools (NSW Planning Portal). A fact sheet from the NSW Minerals Council notes that slamming a door can produce 12 mm/s at the far end of a house and walking on a wooden floor about 3 mm/s (NSW Minerals Council). The USBM numbers aim at cosmetic cracking in the most sensitive materials, plaster and drywall, while masonry and mass concrete tolerate much more (International Society of Explosives Engineers).

The USBM report also records the human side. About 5 to 10% of neighbours judge PPV levels of 0.5 to 0.75 in/s as less than acceptable, and a mean level of 0.50 in/s is expected to leave 15 to 30% of neighbours very annoyed (USBM RI 8507, 1980). A blast can be legal and still produce complaints, which is why a community plan belongs in your control plan.

How to write a mining vibration control plan: 8 steps

A vibration control plan is the document that tells the blaster, the regulator and the neighbours how vibration will be limited and proved. These steps follow the structure used in the rules and guides cited on this page.

Infographic

The blast monitoring loop

1. 1DesignSet burden, spacing, delays and charge per delay.
2. 2FireBlast within the permitted hours and weather.
3. 3RecordCapture PPV, frequency and airblast at the receiver.
4. 4CompareCheck the record against the limit and the prediction.
5. 5AdjustChange the next design using the result.

1. List the receivers. Mark the nearest houses, schools, churches, pipelines, dams, tunnels, power lines and any underground workings. 30 CFR 816.67 requires structures outside its list, such as pipelines and dams, to get their own approved limit.
2. Set the limit for each receiver. Use the regulator’s limit if there is one. If not, use a recognised basis such as the USBM frequency curve for damage or the 5 mm/s comfort level for people, and write down which one you chose and why.
3. Measure the distance. Record the distance from each blast to each receiver. Distance is the input to watch: in one coal mine dataset it was the variable most strongly correlated with PPV (correlation coefficient -0.67, Scientific Reports).
4. Fix the maximum charge per delay. Start with a scaled-distance rule (calculator below), then replace it with a site law built from your own seismograph records.
5. Design the firing sequence. Use delays between holes so the waves from individual holes do not arrive at a house at the same moment; the NSW fact sheet lists this together with blast orientation, stemming and the hole pattern as standard controls.
6. Place and mount the monitors. Put at least one at the nearest receiver and one at the critical structure. Follow the coupling and calibration rules in the next section.
7. Check the weather and the time. Overpressure depends on temperature, cloud, wind speed and direction, so many mines check conditions before firing and blast in set hours, typically 9 am to 5 pm (NSW Minerals Council).
8. Record, review and tell people. Keep a record per blast, compare it with the limit, adjust the next design and tell the neighbours when you will blast.

Where to put the seismograph and how to keep it accurate

A reading is only as good as the sensor mounting. A guidance note from the Hong Kong Civil Engineering and Development Department (GN 10) sets out practical rules based on the International Society of Explosives Engineers (ISEE) performance specification for blasting seismographs (CEDD GN 10).

• Frequency range: the sensor should cover 2 to 250 Hz, and sample at 1,000 samples per second or more per channel.
• Calibration: at least once a year by the maker, an authorised agent or an accredited laboratory. If the geophone is separate from the recorder, calibrate recorder, geophone and cables together as a set.
• Coupling: the note does not recommend spiking a geophone into the ground, because it is hard to be sure the sensor is properly coupled. Bolting or gluing it to a prepared base gives reliable results, and a sandbag is acceptable only where expected acceleration is under 1.0 g and the readings are not close to the limit.
• Site: avoid ground over loose fill, the edge of a berm or the area under a concrete pavement.
• Comparison checks: if the operator and the regulator both monitor, mount their geophones side by side with the same trigger level and sampling rate.
• Records: note the instrument, method, location, date and time for each blast, and keep the monitoring records.

Where the scaled-distance method is not used, the US federal rule asks for a seismographic record for every blast, and for airblast systems with an upper-end flat response of at least 200 Hz.

Scaled distance: how much explosive can you fire per delay

Scaled distance is the distance to the receiver divided by the square root of the charge per delay. The US surface coal rule uses it to let operators skip seismic monitoring: the allowed charge in any 8-millisecond period is W = (D / Ds) squared, where W is in pounds, D is the distance in feet from the blast to the nearest protected structure and Ds is the scaled-distance factor (30 CFR 816.67(d)(3)). The factors are 50 for 0 to 300 ft, 55 for 301 to 5,000 ft and 65 beyond 5,000 ft. A regulator can approve a modified factor if seismograph records of your own blasts show the PPV stays under the limit at a 95% confidence level.

Chart

Maximum charge per 8 ms delay by distance, US coal rule

Pounds of explosive, W = (D / Ds) squared, with Ds 50 to 300 ft and 55 beyond

The calculator below applies this formula. It is a screening tool for that one rule, not a blast design, and other mine types and countries work under different rules.

Airblast limits and what drives them

Airblast limits depend on the lowest frequency your microphone system can measure, because blast overpressure is dominated by low frequencies that are sometimes inaudible but can be felt (NSW Minerals Council). The US rule sets 134 dB peak for systems flat down to 0.1 Hz, 133 dB for 2 Hz, 129 dB for 6 Hz and 105 dBC with slow response where the regulator approves it. The NSW criterion is 115 dB Lin Peak with 5% of blasts allowed up to 120 dB. The scales are not interchangeable, so quote the weighting and the system response with every number.

Chart

Airblast limits in dB (US coal rule and NSW criteria)

Peak levels; US values depend on the measuring system’s low-frequency limit

The NSW fact sheet adds a useful reference point: a 40 km/h wind can produce 130 dBL, more than the limits set for blasting. Wind, cloud and temperature also change how far the pulse carries, which is why firing decisions often include a weather check. The US rule also bars flyrock, rock thrown from the blast, from travelling more than half the distance to the nearest occupied structure, beyond the area of control or beyond the permit boundary.

Why frequency changes the limit

Blasting turns most of the explosive energy into broken rock; the leftover energy shows up as ground vibration and airblast. How a building responds depends on the frequency and size of the vibration and on the building’s mass and stiffness, and a building that moves is not necessarily a building that is damaged (International Society of Explosives Engineers).

Chart

USBM safe peak particle velocity by frequency

Inches per second, threshold cosmetic damage

The same PPV does different work on a house at different frequencies. Houses respond more strongly to low-frequency shaking. The USBM tests found that, below 40 Hz, the safe PPV falls to 0.75 in/s for modern drywall homes and 0.50 in/s for older plaster-on-lath homes, while above 40 Hz a constant 2.0 in/s was recommended for all houses (USBM RI 8507, 1980). The criteria apply to threshold cosmetic damage in the most susceptible materials (ISEE).

In practice, a modern seismograph records the whole waveform, and the engineer checks the dominant frequency of each blast, not just the PPV. Duration matters too: the Kalgoorlie example below shows residents reacting to shaking that lasted longer than three seconds.

Drill and blast data analysis: what to record and why

Data analysis in drill and blast means turning the records of drilling, loading, firing and monitoring into the next blast design. It does not need a large software platform to start. A disciplined table of the following fields for every blast is enough for a first site law.

• Hole data: collar position, depth, diameter, burden, spacing, subdrill and the as-drilled survey. Drill rigs that log penetration rate, pressure and torque (measurement while drilling, MWD) give a rock-strength record along each hole. Treat MWD as a record of how hard each hole was to drill, and compare it with the blast result.
• Loading data: explosive type, weight per hole, stemming length and the charge per delay.
• Timing: the delay between holes and between rows, and the detonator type.
• Monitor data: PPV on three axes, dominant frequency, airblast, distance and bearing to each blast.
• Outcome data: fragmentation, muckpile shape, backbreak, flyrock and oversize counts.

From a scaled-distance rule to a site law

Plot PPV against scaled distance for the last 30 to 50 blasts on a log-log chart and fit a line. The line is your site law. It predicts the PPV at a house from the charge and distance, and it lets you check a proposed blast before you fire it. A coal mine study in China built a new empirical equation by dimensional analysis and then tested machine learning models for PPV, with distance to the monitoring point as the strongest single factor (Scientific Reports). Machine learning models are fitted to individual sites, so test one on blasts it has not seen before you use it for a limit.

What the analysis should change

Use the records to answer three questions after each blast. Did the PPV and airblast at the nearest receiver match the prediction? Did the rock break as planned? If PPV was higher than predicted, which input changed: charge per delay, timing, burden or the rock? Over a few months the answers show which holes to shorten, where to change the delay and where the geology is harder than the plan assumed.

▶ Explains the jobs an AI mining app can do, from finding places to look to planning a mine. · 3:52

Case: blasting next to a town at the Kalgoorlie Super Pit

The KCGM Super Pit sits beside Kalgoorlie-Boulder in Western Australia. Its environmental review for the Golden Pike cutback, prepared with a blasting consultant, shows a plan built on monitoring and prediction. Blast vibration from the pit had to stay under the Australian Standard value of 10 mm/s at houses, and no more than one in ten consecutive blasts could exceed 5 mm/s. Airblast was capped at 125 dBL between 07:00 and 18:00, Monday to Saturday (120 dBL on Sundays and public holidays), with no more than one in ten blasts above 120 dBL (KCGM Stage 3 environmental review, Appendix E2).

The consultants fitted a prediction model to data from six routine monitoring stations. They concluded that worst-case blasts at the pit perimeter would stay at or below 5 mm/s at privately owned houses, with average levels under 2 mm/s. The same report notes that some residents became concerned at about 5 mm/s when the vibration lasted longer than three seconds, and that electronic detonators helped by splitting a blast into several shorter sequences with a short delay between them. The lesson is the one in the plan above: set the limit, model it from your own records, and manage duration as well as peak.

For more on how the Super Pit region manages land and water around its operations, see this guide to Kalgoorlie gold mining stewardship.

Community and environment: beyond the limit

A blast that passes the limit can still raise complaints, so the control plan should cover people as well as compliance. The NSW fact sheet lists consultation as a regulatory requirement in many cases in New South Wales, with monitoring near the closest homes, notice of blast times and structural property inspections for residents, typically within 2 km of a rural operation. Publishing the monitor results gives neighbours a record they can check, so they can check whether a blast was larger than usual.

Vibration is one of several effects of mining on land and neighbours. The video below explains seven of them in plain words, and the open-pit guide on this site covers them in more depth: why open pit mining can harm the environment.

▶ A plain-language claymation on the seven environmental impacts of mining. · 2:31

Where satellite data fits next to blast monitoring

A satellite cannot measure blast vibration, and it does not replace a seismograph. What it can do is supply the site context around the pit. Multispectral imagery shows pit growth, dump shape, bare ground and vegetation change over months, and it gives background for planning haul routes and site layout. Farmonaut Mining Pro, a satellite-based mineral detection platform, screens a licence area from multispectral and hyperspectral imagery to flag target zones, alteration halos and faults; it is built for the earlier question of where to drill, and it produces exploration targets, not resource estimates. Fleet tracking tools, such as Farmonaut fleet management, address haulage after the blast, and carbon footprinting covers site emissions reporting.

For the optimisation side of the same topic, including drill accessories and pattern changes, read drill and blast analysis and optimisation. For the equipment side, see mining tool suppliers for safer drilling.

▶ A short look at Farmonaut Mining Pro, which turns a licence boundary into exploration targets from satellite layers. · 4:56

Common gaps in a vibration control plan

• A limit with no stated basis. Say whether 5 mm/s is a comfort criterion or a damage limit, because the two differ by about a factor of ten.
• PPV without frequency. A single number hides the part of the signal that matters for houses.
• One monitor, one position. The nearest house may not be the most exposed; directional effects and geology change the pattern.
• An uncalibrated sensor. Annual calibration and side-by-side checks are in the guidance note cited above.
• No feedback loop. If monitor results do not change the next design, the monitoring only records the problem.
• No weather rule. Overpressure depends on temperature, cloud and wind.

Small quarries and gem or stone operations blast too, and the same logic scales down to a single monitor and a short plan. For a gemstone mining topic, see the amethyst mining guide.

For a closer look at a related question, see our guide: Copper Mining Health Risks: Limits, Data, Prevention.

If this topic matters to you, read Gravity Separation of Copper Ore: Methods, Limits, Steps next.

Frequently asked questions

What is blast vibration monitoring?

It is the measurement of ground vibration and airblast from each blast with a seismograph and a microphone, followed by a comparison with the limit in the permit. It produces a record per blast that shows compliance and feeds the next design.

What is a safe vibration level for a house?

The USBM research recommends 0.75 in/s (19 mm/s) for modern drywall houses and 0.50 in/s (12.7 mm/s) for older plaster houses below 40 Hz, and 2.0 in/s (50.8 mm/s) above 40 Hz. These prevent cosmetic cracking; comfort limits such as 5 mm/s are much lower.

What is the blasting vibration limit in Australia?

In New South Wales the typical criterion is 5 mm/s, with 5% of blasts allowed up to 10 mm/s in a year, and airblast of 115 dB Lin Peak, with 5% allowed up to 120 dB. Other states and individual approvals can differ, so check the licence conditions.

What does PPV mean in blasting?

PPV is peak particle velocity, the highest speed at which a particle of ground moves during the blast. It is measured on three axes, and the largest is usually compared with the limit.

How do I calculate the maximum charge per delay?

Under the US surface coal rule, divide the distance in feet to the nearest protected structure by the scaled-distance factor and square the result. The result is the maximum pounds of explosive in any 8-millisecond period. Use the calculator on this page for the arithmetic.

How often should a blast monitor be calibrated?

The Hong Kong guidance note, based on the ISEE specification, asks for calibration at least once a year by the maker, an authorised agent or an accredited laboratory.

What is the difference between ground vibration and airblast?

Ground vibration moves through the earth and is measured in mm/s or in/s. Airblast moves through the air as a pressure wave and is measured in dB. Ground vibration arrives first.

How do electronic detonators reduce complaints?

They let the blaster set exact delays, so one blast can fire as several short sequences. At Kalgoorlie, the consultants reported that this reduced concern from residents who had noticed vibration lasting more than three seconds.

Can machine learning predict blast vibration?

Studies fit machine learning models to PPV data from single sites, for example at a coal mine in China, and compare them with empirical equations. The models need site data and testing on unseen blasts before you rely on them for a limit.

Does a small quarry need vibration monitoring?

That depends on the licence and the distance to neighbours. Many permits require a seismograph record when homes are within a set distance, and a monitor is a low-cost way to show the neighbours that blasts stay within the limit.

Can satellite imagery measure blast vibration?

No. Satellites show surface changes over time, such as pit growth or vegetation, but vibration needs a seismograph on the ground.