Discover and read the best of Twitter Threads about #earthquakes

Most recents (5)

Subduction-zone mega-thrust #earthquakes, the most powerful earthquakes, can produce #tsunamis through a variety of structures that are missed by simple models. (THREAD)
The basic model shows rock above the convergent plate boundary being compressed and bent as it stores elastic energy. Once friction is overcome, the overriding plate slides abruptly up the fault causing the leading edge to heave seawater upward generating a #tsunami.
In 2011, the M9 #Japan #earthquake ruptured a fault area 500kms x 200kms over an interval of nearly 3 min. Surveys of sea-floor bathymetry before and after the earthquake document up to 50 m of fault displacement at near the Japan Trench.
Read 15 tweets
Hi @GlenPhillips and @ToadWetSprocket! You asked me a question about #earthquakes in the PNW at one of your shows DC in Aug (that’s me in the @500womensci shirt). I’ve finally got a more complete response for you! (THREAD)
The Pacific Northwest is a region of high #earthquake risk because of megathrust earthquakes on the plate boundary, deep earthquakes within the subducting plate, and shallow crustal earthquakes.
Along the western edge of the PNW, the Juan de Fuca Plate dives beneath the margin of the North American Plate in a process called subduction. On Jan 26, 1700 a M9 earthquake ruptured the full 1,000 km length of that plate boundary.
Read 21 tweets
Japan has more measurable #earthquakes than any other country. This is because #Japan is wedged among four major tectonic plates. (Thread)
80% of earthquakes worldwide occur around the circum-Pacific region chiefly along the subduction-zone boundaries, known as the “Pacific Ring of Fire”, so named because of the more than 400 active volcanoes that occur there.
The earthquake and volcano belt sweeps through Japan where about 20% of worldwide measured earthquakes occur. There are more than 100,000 earthquakes recorded in Japan every year. Of those about 1,500 are strong enough for people to notice.
Read 18 tweets
So here are my extended thoughts on the #KenyaCrack, or #KenyaGully if you prefer. The narrative that’s going around is that this is a great gash that opened up and is splitting Africa in two. That's incorrect. Africa is being split but very slowly. This is called rifting.
Riting is definitely happening in Africa. This is not really disputed. There is lots of scientific literature on the subject.…
But rifting occurs over a very long period of time, like millions and millions of years.
Rifting progresses through earthquakes and volcanic eruptions and other geologic forces. Here is an animation showing how the crust thins before it splits. (This example is from the US, but the process is similar)
Read 17 tweets
I keep hearing 7.1+ & seeing Oaxaca
Just putting this here^…
I seem to have missed this one:…
Read 69 tweets

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