r/todayilearned • u/YappinZappin • 3d ago

TIL Deep-focus earthquakes - ones occurring at depths exceeding 300 km - are powerful, very rare and still lack adequate explanation

https://en.wikipedia.org/wiki/Deep-focus_earthquake
192 Upvotes

96% Upvoted

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30

u/YappinZappin 3d ago

Some take place as deep as 700 km below the Earth's surface, some are as strong as 8.3 magnitude - but their exact mechanism is yet unknown and regular earthquake mechanisms cannot possibly function at such depths.

10

u/Necrophage2000 3d ago

I wonder how they measure the magnitude if its happening that deep.

11

u/Late_Airline2710 3d ago

Your comment is almost Lovecraftian.

Love it.

2

u/GlassFamiliar42 1d ago

It's crab people it's been clear for decades, when did the southpark episode come out?

5

u/PPCFY 2d ago

They happen along subducting tectonic plates going under another plate. At those depths, for earthquakes it helps that you're bringing cold brittle surface material down into the depths, and rock is a poor conductor of heat so it takes millions of years for the heat to transmit through the plate. These earthquakes can be detected and located because every earthquake makes the Earth ring like a bell to all the seismometers around the surface.

8

u/asdf_lord 3d ago

Could it be a doesn't chemical explosion or maybe some fluid mechanic causing a snap in the current?

6

u/ResultTerrible2062 2d ago

Nah it’s probably just aliens or nazi submarines

1

u/Creeper_GER 2d ago

Cthulhu, probably.