M7 slow release earthquake under Wellington

[Deano]

From Geonet.
GeoNet’s continuously-running GPS instruments in Wellington and Kapiti show that the Pacific and Australian tectonic plates are slipping past each other more rapidly than usual. This has been going on since January of this year, and will most likely continue for several months. These movements represent the equivalent of a magnitude 7 earthquake on the plate boundary, at 40 km depth.
To the west of Wellington, the equivalent of a magnitude 7 earthquake is happening right now, 40 km below ground. This would be Wellington’s largest earthquake in 150 years, yet nothing is felt at the surface. Even our sensitive earthquake recording instruments hardly notice a thing. This is because, unlike a normal earthquake, these plate movements happen very slowly in a process known as “slow-slip events”. This Kapiti slow-slip event is affecting an area spanning over 100 km from Levin to the Marlborough Sounds. Conventional earthquakes happen when one side of a fault moves past the other suddenly. A similar process occurs with slow slip, except it takes much longer for the fault to move and release energy, this is why slow-slip events are often called silent earthquakes.
Full story on GeoNet

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