What's Causing All These Earthquakes Today?

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SUMMARY

The recent seismic activity includes a Mw5.9 earthquake in northern Indonesia, a Mw6.3 aftershock in Chile, and a Mw6.5 event in Vanuatu, followed by a Mw6.6 quake in the central Mid-Atlantic Ridge, northeast of Brazil. These earthquakes are primarily caused by the complex interactions of oceanic spreading ridges and transform faults. The Mid-Atlantic Ridge is not solely a spreading ridge; it features a combination of spreading and fault zones, which contribute to the occurrence of these seismic events.

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  • Understanding of seismic magnitude scales (Mw)
  • Knowledge of tectonic plate movements and interactions
  • Familiarity with oceanic spreading ridges and transform faults
  • Basic skills in interpreting seismic data and maps
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  • Research the geological features of the Mid-Atlantic Ridge
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  • Explore seismic monitoring tools and techniques, such as seismographs
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Geologists, seismologists, and anyone interested in understanding the dynamics of tectonic plates and earthquake phenomena.

davenn
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http://www.sydneystormcity.com/seismograms.htm

MY seismo has been busy over the last 4 hours

Mw5.9 northern Indonesia

Mw6.3 Chilean aftershock

And coming in now a Mw6.5 Vanuatu ( SW Pacific)
 
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davenn said:
and another large event coming in...

Mw 6.6, central Mid-Atlantic Ridge, NE of Brazil

https://earthquake.usgs.gov/earthquakes/eventpage/us7000biu8/executiveIt will be relatively small amplitude on my seismo as it's half way around the world
This event is ~ 600km NW of a Mw6.5 on the 30th Aug 2020
What causes earthquakes there? Aren't the plates drifting apart?
 
fresh_42 said:
What causes earthquakes there? Aren't the plates drifting apart?
Yes, they are spreading apart. There are lots of very large transform ( strike-slip) faults along all oceanic spreading ridges
and that's where these quakes usually occur as did this one ...

a couple of maps I have done, one annotated with which parts are spreading and which parts are transform faults

clean map showing quake location ...

Clipboard01.jpg


annotated map

Clipboard01a.JPG
Many people probably think that the Mid-Atlantic Ridge ( and others like it) are just spreading ridges.
This couldn't be further from the truth as it can be seen that it is a complex mix of spreading and fault zones
I have 1/2 arrows that indicate the relative motions on some of the faults ( didn't do all - for clarity)

cheers
Dave
 
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