This information applies to all possible causes of deformation and/or damage. Although the mentioned root-cause below is (induced) seismic activity, the same rules apply to all graphs regardless invoked by construction activities, natural subsidence and/or any other possible root-cause, leading to deformation.

Earthquake resulting in damage

Below two simplified animations are showing a transversal surface wave passing a building. The solely purpose of these animations is to help you understand our data and should not be interpreted as scientific correct.

Subsidence / Tilt

Tilting subsidence as result of an earthquake.


Rupture as result from an earthquake


Both plots below show a significant "drop" in the middle of their domain. In X-direction (top-plot) the tilt of the wall (structure) where the sensor is mounted suddenly "drops" at the same moment in time the earthquake waves pass the structure. At the same moment the Y-direction (bottom-plot)  also drops, although significant less then the graph of the top plot.  After the event both graphs do not return to their pre-event level.

Sudden change in tilt of a structure

Conclusion:  The part of the structure where the sensor was mounted, never returned to the same position as before the event. In the X-direction the tilt of the wall shifted by minus 4.7x10-3 degrees. The shift in the Y-direction is less than 2x10-3 degrees.  Since the wall did not return to its original position plastic deformation occurred.


The graph below shows the total arc (the difference between the highest measured value and the lowest measured value) during the passage of the quake.

The total arc during the quake

Both spikes represent the maximal readings during the quake. This means the total rotation from "left to right"as the quake passes.

The total arc recorded during the passage of the transversal waves

Conclusion: During the earthquake, in X-direction the wall rotated 0.02 degrees. And in Y-direction 0.025 degrees.


Below the Peak Ground Accelerations (PGA) in respectively X-, Y- and Z-direction. These measurements are te Peak Accelerations within sample periods from 5 seconds measured with a sample rate from 400Hz each channel.

Peak (ground) Accelerations during an (induced) earthquake due to gas exploration. (Measured in the Netherlands)

Conclusion: During the, by gas exploration induced, earthquake the following Peak Ground Accelerations where recorded:

  • In X - direction:0.24 m/s2
  • In Y - direction:0.085 m/s2
  • In Z - direction:0.34 m/s2

Final conclusion

Given the local conditions, this was a relatively severe earthquake, that rotated and translated the wall in all directions. Based on the tilt meters it is obvious plastic deformation occurred.

Due to the fact that vibrations and accelerations are showing clear spikes at the same time as the "drop" in tilt, one is allowed to conclude that the earthquake is the direct cause of the deformation.

Additional explanation

At first glance a tilt drop of only 0.0047 degrees seems insignificant. But take into account that a sensor is often mounted in the foundations of a building. It is very likely that the rooftop is 8 meters (the radius) or higher above the foundations. In that case the top of the building shifted 0.66 mm. That by itself doesn't have to lead to visible damage.  But at the fifth quake this sums up to 3.3 millimeters. That will rupture brick walls.

Indicating calculation

Stiff deformation = Number of deformations x radius x tangent(post-event tilt - pre-event tilt)

In numbers:

Stiff deformation = 5 x 8000 x tan(0.4962 - 0.4915)

Stiff deformation = 3,3 millimeter.