A place south of Greenland/Iceland is seeing a lot of seismic activity in recent days, and as I speak, a quake-cam I sometimes follow is tracing some nice squiggles from a 5.9 in the region. Is an underwater volcano erupting, or do they know? What is the risk of a tsunami, if any? I find all of this quite interesting.
I blame the Russians.
How close is it to an actual fault line?
Right on it; it’s just that a lot of quakes are happening in the same place all at once.
Every time I see something like this, I go check to see if Surtsey is in the news. I still remember the excitement of the new island being explained to me as a wee child.
I think Anak-Krakatoa (“Child of Krakatoa”) is pretty cool, too. I had heard of Surtsey, but didn’t know until just now that it formed from TWO adjoining vents. Yep, it has two craters.
If vegetation starts to sprout on this new Tongan island, that will definitely slow down erosion.
That’s not what consolidates new volcanic islands. There’s no soil for plants to grow in on such an island, just volcanic rock and ash. It’ll be many years before substantial plants will grow on a new volcanic island.
What’s needed is for the volcano’s mouth to be isolated from the ocean water and then for it to pour out a bunch more lava to cover the loose rock. When lava hits water, it explodes, which means the lava is broken up into smallish rocks. If the volcano can grow big enough to send the lava into air, the lava could consolidate that loose rock into a more permanent island.
Hmmm, I’m not seeing those quakes. Living in the San Francisco area, I have a vested interest and I’ve signed up for the USGS alerts but I haven’t gotten any for that area. Are they recent quakes, within the last month?
The ice melt is creating changes in the earth’s gravity in the area. The weight of the land and water over the sea bed are changing. I can’t recall what this phenomena is called but it results in an actual sea level drop locally and rise far away.
The local changes in gravity could easily induce seismic activity.
Here’s a link to a map. You can move the map around to anywhere in the world.
https://earthquake.usgs.gov/earthquakes/map/?extent=21.37715,-153.10547&extent=63.90152,-46.23047
Paging our resident geologist @MrDibble
I’m not a geology buff, but since you haven’t had a geologist reply yet.
It’s the Mid-Atlantic ridge. The continental plates are pulling apart (which I’m sure you know) and it has seismic activity all the time.
Here’s a map for the North Atlantic part of the ridge for this year to date. Earthquakes all up and down the ridge.
As a non-expert I’d say you are looking at random noise in a noisy system.
The Northern Mid-Atlantic Ridge activity (which is pretty much constant) generally isn’t, by its divergent nature, likely to cause the kind of tsunamis most folks need to worry about. In contrast to the convergent margins that cause all the trouble in the Pacific and Indian Oceans.
Here, have a paper on it.
Got it. Thanks for that.
This is my preferred map for seismic activity.
If you drill into the Mid-Atlantic area, you can get a list of recent earthquakes. I played around with it, and got here:
That’s the last week of activity and you can animate to see all the quakes pop up
You also have isostatic rebound, which could also be caused by the removal of the weight of the ice, in which the rock expands due to less pressure, which could cause sea level rise in some places and a fall other places, and could also lead to seismic activity. Although I do not know how soon that would happen or at what distance.
Thanks @Zyada !
Or, for that matter, how thick an ice sheet would need to be or how rapidly it would have to shrink in order to cause measurable quakes.
I have heard that there’s an island in either the Azores or the Canary Islands that has the potential to generate a tsunami, should part of it break off in a landslide.
Those things could be working together. But I don’t know if any recent activity is directly related. There’s just a lot of things going on right around there and everywhere else affected by the ice melts and all the other seismic activity. Some days in that region are likely to be shakier than others.
Any activity from isostatic rebound is going to pale into insignificance compared to the activity produced by the Ridge itself. Especially the Reykjanes Ridge portion, where you have that powerful combo of a spreading centre and a hotspot.