Prism Movement TARP Checker
Classifies a monitored slope movement rate against Trigger Action Response Plan (TARP) alert bands — Green, Amber, Orange or Red — and returns the recommended response for each level. Used by geotechnical engineers, slope-monitoring technicians and mine ground-control teams reading prism, radar or extensometer data.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the current movement rate in mm/day from your monitoring system.
- Enter the amber, orange and red rate thresholds from your site's TARP (defaults 5 / 20 / 50 are illustrative only).
- Read the alert level and the recommended action; escalate per your site's formal TARP.
How it works
A TARP defines escalating alert levels tied to trigger values. This checker uses the movement rate: Green while the rate is below amber, Amber from amber up to orange, Orange from orange up to red, and Red once the rate reaches or exceeds red.
The thresholds are site-specific and set by a geotechnical engineer in the site's Ground Control Management Plan. Velocity is only one trigger — a complete TARP also uses acceleration (inverse-velocity), total displacement, extent, groundwater and visual observations.
Worked example
Prism reading of 8 mm/day. With thresholds amber 5, orange 20 and red 50 mm/day, a rate of 8 satisfies amber ≤ rate < orange (5 ≤ 8 < 20), so the alert level is AMBER: increase monitoring frequency and notify the responsible engineer.
Common mistakes
- Using the illustrative default thresholds (5 / 20 / 50) operationally instead of the site TARP values.
- Relying on velocity alone — ignoring acceleration (inverse-velocity), total movement and visual signs.
- Comparing a rate in mm/hour or mm/week against thresholds in mm/day; keep units consistent.
Frequently asked questions
What is a TARP in slope monitoring?
A Trigger Action Response Plan defines escalating alert levels (typically Green, Amber, Orange, Red) each tied to a trigger value such as movement rate, and lists the actions required at each level up to evacuation.
Where do the thresholds come from?
From the site's Ground Control Management Plan, set by a geotechnical engineer for the specific pit, wall or structure. The defaults in this tool are illustrative only.
Is movement rate the only trigger?
No. A robust TARP also considers acceleration (often via inverse-velocity), cumulative displacement, the extent of the moving zone, groundwater and visible cracking.
What happens at a Red alert?
Red means evacuate personnel and equipment and stop work in the affected zone immediately, and do not re-enter until a competent person clears the area.
Related tools
- Prism Movement Rate Calculator
- Rainfall Trigger Checker
- Saturated Slope FoS Calculator
- Pore Pressure Ratio Calculator
- Crack Displacement Calculator
- Cumulative Movement Calculator
Explore more in Geology, Geotechnical & Ground Engineering.
Tip: Enter any known values to calculate the remaining results.
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