Seismic structural monitoring instruments a building or piece of infrastructure with accelerographs to record how it actually moves during an earthquake, from foundation to roof, not just how strong the shaking was at ground level. That record lets owners and engineers make fast, defensible decisions about whether a structure is safe to reoccupy, what needs inspecting, and how it really performed. In New Zealand, where major earthquakes are a matter of when rather than if, that is the difference between guessing and knowing.
New Zealand sits on some of the most active fault systems in the world. Every building owner, council, port operator, and infrastructure manager here already knows the risk. What fewer organisations have is a clear picture of how their specific structure behaves when the shaking happens, and what that means for the decisions that follow. That is the gap seismic structural monitoring fills.
In this article
- What seismic structural monitoring actually measures
- Why it matters in New Zealand
- Who is already doing this
- What the data actually shows
- What good instrumentation looks like
- How to get started
- Frequently asked questions
What seismic structural monitoring actually measures
Seismic structural monitoring is the practice of instrumenting a building or piece of infrastructure with accelerographs to record how it moves during an earthquake, not just how strong the shaking was at ground level. A network of sensors placed through a structure, from foundation to roof, captures how the building responds: drift, torsion, floor-to-floor acceleration, and whether the structural system performed the way the design intended.
This is a different discipline from regional seismic hazard monitoring, which tells you where and how big an earthquake was. Structural monitoring tells you what that earthquake did to your asset.
| Seismic structural monitoring | Regional hazard monitoring | |
|---|---|---|
| Question it answers | What did the earthquake do to my building? | Where and how big was the earthquake? |
| Where the sensors sit | Through the structure, foundation to roof | A regional network, at ground or free-field sites |
| What it outputs | Drift, torsion, floor accelerations, changes in dynamic response | Location, magnitude, regional shaking maps |
| The decision it supports | Reoccupy, inspect, or repair this specific asset | Regional situational awareness |
Why it matters in New Zealand
Three things make seismic structural monitoring a practical necessity here rather than a nice-to-have.
Post-event decisions have to be fast and defensible. After a significant earthquake, building owners, insurers, and engineers need to know quickly whether a structure is safe to reoccupy. Instrumented buildings give engineers real data to work from instead of relying purely on visual inspection and conservative default assumptions, which often means faster reoccupation and lower cost.
Regulation is catching up with risk. The Building (Dam Safety) Regulations 2022 were a clear signal that New Zealand regulators are moving toward requiring structural performance evidence, not just design compliance, for higher-consequence assets. Dams were first. Other high-consequence structures are a logical next step.
Insurance and finance increasingly want evidence, not assumptions. Parametric insurance products reward organisations that can demonstrate they understand and are tracking their structural risk, rather than estimating it. Instrumented buildings produce that evidence as a by-product of normal operation.
Who is already doing this
In New Zealand, structural monitoring has moved well past pilot projects. Councils, ports, and property owners have deployed networks across sites including Wellington City Council assets, Lyttelton Port Company, and major retail and property portfolios.
For New Zealand building owners, that instrumentation underpins Sentinel, our local monitoring service. Sentinel measures the actual shaking at your building, compares it against your building's own design limits rather than a regional average, and delivers a clear white, amber, or red status with an action attached, straight to your phone by app, SMS, and email, within minutes of an event. It is built on NZS 1170.5 and backed by a nationwide sensor network, and it is already protecting buildings for councils, hospitals, airports, and property portfolios around the country, including Christchurch Airport and Wellington City Council. It is a subscription service, so there is no up-front hardware cost or installation project for the building owner to carry.
What the data actually shows
Structural monitoring earns its keep by catching things a visual inspection cannot. Published seismological research has applied advanced signal analysis techniques, originally developed for earth studies, to long-term structural monitoring data from instrumented buildings, tracking subtle changes in a building's dynamic response over time.
The pattern that shows up again and again is a step change in a building's fundamental frequency following a significant earthquake, sometimes by 10 to 15 percent, even where there is no visible structural damage. In some cases the change is concentrated at specific floors rather than spread evenly through the structure, and buildings can show a degree of recovery in the following days before settling to a new baseline.
None of that would have been visible from the outside. It is the kind of change that only shows up in continuous, long-term monitoring data, which is exactly the case for instrumenting a building before an event, not after one.
What good instrumentation looks like
Not all seismic structural monitoring systems are built the same way, and the differences matter more than they might first appear.
Open data. Your monitoring data belongs to your organisation, not to a vendor's proprietary software layer. Systems that output standard formats like MiniSEED, CSV, and JSON, and stream via open protocols like SeedLink, mean your engineers or consultants can pull the data straight into whatever analysis tools they already use. No licence gate, no dependency on the installer to get your own data out.
Array-level timing without extra hardware. Structural monitoring depends on precise synchronisation between sensors across a building. Modern systems can achieve this with a single GNSS timing reference for the whole array, rather than requiring GPS hardware at every node, which keeps larger deployments practical and cost-effective.
Instruments built for the job, not adapted from something else. Structural arrays have different requirements to a single free-field station: more channels, tighter synchronisation, and often a mix of sensor types feeding into one recording point. Purpose-built recorders handle this natively rather than as a workaround.
How to get started
You do not need to instrument an entire portfolio on day one. Most successful programmes start with a single high-value or high-risk asset, prove out the value with real data, and expand from there. Canterbury Seismic Instruments has spent more than two decades building instruments that measure earthquakes in New Zealand conditions, including through the Canterbury sequence itself, and works with engineers and owners to scope monitoring that fits the asset and the budget, not a one-size system.
If you are weighing up whether structural monitoring makes sense for your building, port, or infrastructure asset, the conversation is worth having before the next event, not after it.
Frequently asked questions
What is seismic structural monitoring?
Seismic structural monitoring instruments a building or structure with accelerographs, placed from foundation to roof, to record how it actually moves during an earthquake. It captures drift, torsion and floor-to-floor acceleration, so owners and engineers can see how the structure performed and decide whether it is safe to reoccupy.
How is structural monitoring different from regional seismic monitoring?
Regional hazard monitoring tells you where an earthquake was and how big it was. Structural monitoring tells you what that earthquake did to a specific building. One is about the event; the other is about your asset's response to it.
Is seismic structural monitoring required in New Zealand?
Not universally, but the direction of travel is clear. The Building (Dam Safety) Regulations 2022 moved higher-consequence assets toward requiring structural performance evidence rather than design compliance alone, starting with dams, and insurers and financiers increasingly reward owners who can demonstrate they are tracking structural risk rather than estimating it.
How many sensors does a building need for structural monitoring?
It depends on the structure, but most programmes start small: sensors at the base and roof capture a building's fundamental period and overall drift, and mid-height instruments resolve how motion builds up through the structure. You can begin with a single high-value asset and expand from there.
What is Sentinel?
Sentinel is Canterbury Seismic's New Zealand monitoring service. It measures the actual shaking at your building, compares it against your building's own NZS 1170.5 design limits, and sends a clear white, amber, or red status with an action, within minutes, by app, SMS, and email. It is a subscription service, with no up-front hardware cost for the building owner.
Canterbury Seismic Instruments designs and manufactures seismic recording instrumentation from Christchurch, New Zealand, with a track record spanning more than two decades and the Canterbury earthquake sequence. Get in touch to talk through what structural monitoring could look like for your asset.
