Our thoughts go out to all those who are suffering the major earthquake in Taiwan this weekend. As can be seen from this site the strength of the shake and aftershocks are greater than the actual 6.4 quake. Click on the link and then the arrow to the side of the quake to see how the earthquake developed. The dots are Palert systems that registered the quake as it happened.
http://palert.earth.sinica.edu.tw/

Happy New Year to you all

Just a quick reminder about the Intensity V Magnitude of an Earthquake. While there is a correlation it is often not linear. Instruments measure the intensity of an earthquake using Peak ground acceleration (PGA). This is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. Measured in gravity (g) or Gal where 1g=981Gal. The magnitude often using the Moment Magnitude (often mislabelled as Richter) scale is the amount of energy released.

Cliffhanger part of Earthquake Shakemap Trial in Wellington.

The house in Wellington featured on New Zealand Grand Design - and hanging OFF the 45 degrees cliff face - is one of a number of sites in the area that have the low cost Palert system installed. Connected back to a secure central server the Palerts provide data to enable shake maps to be produced within seconds of an event.  These are the initial units to be deployed and will eventually be part of a more sophisticated early warning system.

The house hangs from the cliff face and as such the units showed there is a very small strain on the foundation of under 0.2 gal (ground acceleration). Not surprising as most of the house hangs out over the cliff. An amazing piece of engineering. For more information on the house see :-
Grand Designs cliff-hanger creates prototype for steep sites

New Zealand Earthquake warning system trial
An earthquake early warning system that provides a precious cushion of reaction time before the destructive shaking arrives is being trialled in the Western Bay of Plenty.