Wednesday, 1 April 2020

Slow Earthquakes

Slow Earthquakes

I had heard of such things but did not know much about them, so I was interested in reading THIS ARTICLE. After reading the article I realise that calling them earthquakes is dramatising something with no drama at all! 

An earthquake releases a lot of energy very quickly. A "slow earthquake" can release the same amount of energy but over a period of months or even longer. Is a slow earthquake somewhere between rocks moving steadily and moving in earthquakes? Can a slow earthquake trigger a catastrophic one nearby?

What makes an area have slow earthquakes rather than a catastrophic one? The author (from Cardiff) has been working in New Zealand where the Hikurangi subduction zone off the south eastern coast of the North Island demonstrates slow earth earthquakes in a conveniently shallow and accessible place. 

He hypothesises that the very variable seafloor rocks and sediments may have something to do with it. Also the presence of seamounts, pressurised fluids decreasing frictional resistance, seafloor roughness and other things might be involved. Obviously we are in a phase of looking for a cause.

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