Earthquakes and climate change

[vox_mundi]

Solved: How Tides Can Trigger Earthquakes
https://phys.org/news/2019-06-tides-trigger-earthquakes.html

Years ago, scientists realized that earthquakes along mid-ocean ridges—those underwater mountain ranges at the edges of the tectonic plates—are linked with the tides. But nobody could figure out why there's an uptick in tremors during low tides.

"Everyone was sort of stumped, because according to conventional theory, those earthquakes should occur at high tides," explained Christopher Scholz, a seismologist at Columbia University's Lamont-Doherty Earth Observatory.

In a study published today in Nature Communications, he and his colleagues have uncovered the mechanism for this seeming paradox, and it comes down to the magma below the mid-ocean ridges.

... In the end, it came down to a component that no one else had considered before: the volcano's magma chamber, a soft, pressurized pocket below the surface. The team realized that when the tide is low, there is less water sitting on top of the chamber, so it expands. As it puffs up, it strains the rocks around it, forcing the lower block to slide up the fault, and causing earthquakes in the process.

Furthermore, said Scholz, the tidal earthquakes in this region are "so sensitive that we can see details in the response that nobody could ever see before." When the team charted the earthquake rate versus the stress on the fault, they realized that even the tiniest stress could trigger an earthquake. The tidal data helped to calibrate this effect, but the triggering stress could be caused by anything—such as the seismic waves from another earthquake, or fracking wastewater pumped into the ground.

... "People in the hydrofracking business want to know, is there some safe pressure you can pump and make sure you don't produce any earthquakes?" ... "And the answer that we find is that there isn't any—it can happen at any level of stress."

Open Access: Christopher H. Scholz, et.al., The mechanism of tidal triggering of earthquakes at mid-ocean ridges, Nature Communications 10, Article number: 2526 (2019)

[Tom_Mazanec]

Big earthquakes can make sea level rise worse:
https://www.nationalgeographic.com/science/2019/06/big-earthquakes-might-make-sea-level-rise-worse/

[TerryM]

Thanks Vox M


Having that island racing along at such velocities reminded me of the good Congressman's fears that Guam might tip over if troop levels were increased.


As long as this island doesn't slip away into enemy hands I don't expect that there will be military intervention. Damn lucky it isn't Diego Garcia making a break for freedom!


Terry

[TerryM]

Not sure how to incorporate AGW, but the 7.1 quake in So.California are lighting up the wife's phone as friends and relatives report their experiences from the region.


The 7.1 quake at ~9:20 PM PDT or ~3:20 AM UTC was unusual and is leaving normally unflappable locals hoping this isn't a precursors of "The Big One" that all Californians fear.


Our first phone call was from Apple Valley California after a 6.4 quake on Thursday morning when Carole's niece called to reassure us that all was well. The continuing aftershocks, particularly the 7.1 last night had friends/relatives reporting from Riverside California, Pahrump Nevada and Las Vegas that they were well, but that the continuous aftershocks were straining their nerves.


The epicenter, 11 miles from Ridgecrest is north of the (in)famous San Andreas fault, but quite near Furnace Creek Ranch, site of the world's highest recorded temperature, (56.7 C - 134.1 F on July 10th in 1913, or if that's discarded then at 54.0 C - 129.2 F on June 20, 2013). Last night's temperature there was only 51.0 C or 123.8 at the time of the quake according to the Dark Sky weather site. They're not expected to be up to 53 C (127.4 F) until the later half of next week.


I still don't connect AGW with earthquakes - unless we include isotropic rebound - but if So. California's long overdue "Big One" occurs while the region is experiencing record temperatures, we'll find plenty to argue the case. Furnace Creek Ranch set world records for high monthly temperatures in 2017 and 2018.


Edit: The initial figure of 7.1 has been downgraded to a 6.9, still an outrageously powerful quake.


Terry

[kassy]

Here is a fun connection for you:

The linked article points out that as sea level continues to rise, the groundwater levels beneath coastal areas will also rise, and those areas subject to strong ground motion may be subjected to liquefaction of the soil:

Title: "An Ancient City’s Demise Hints at a Hidden Risk of Sea-Level Rise"

https://www.theatlantic.com/science/archive/2019/06/earthquakes-and-sea-level-rise-are-deadly-combination/592945/

Extract: "Two millennia ago, an earthquake liquefied the ground beneath the Egyptian port of Thonis-Heracleion.
…
Even the smallest increase in the level of a local water table can raise a city’s risk of liquefaction. If a modern-day Thonis-Heracleion were to experience floods—say, worse than usual, thanks to rising seas—and then suffer a quake, the devastation could be cataclysmic, sending dozens or even hundreds of structures crashing down within seconds. That’s the promise of sea-level rise in many liquefaction-vulnerable places. Little by little, the water table rises, and after one flood, a quake comes, and the soil turns to liquid, to a weakened goo incapable of supporting the heavy brick and steel and broad wood beams erected upon it."

[TerryM]

There have been 40 aftershocks in the first 14.25 hours of today, Sunday July 7th that rank between 3.0 and 4.3 on the Richter Scale.


kassy
Sea level rise won't be a problem in the High Desert, but there are a number of underground rivers near by, some well mapped, some possibly mythical.
Hot Springs, Warm Springs and a large number of dried lakes indicate that there may still be a volume of water deep beneath the surface.
At the North end of Death Valley, Ubehebe Crater exploded ~1,500 yrs ago when a buried lake interacted with magma. Not long ago in geological time.


Ridgecrest is (in)famous for having more PHDs/populace than any other town in the US since it's a bedroom community for the China Lake Naval Air Weapons Station. Hope they haven't been weaponizing earthquakes (or testing Trumps new nukes deep underground.) 


Terry

[Bruce Steele]

Terry, It is about 250 miles from here to Ridgecrest and it was strong here with roll lasting about twenty seconds. I moved rooms and aligned with the roll. I pointed to the direction of the quake,
and guessed correctly. I can think of three other quakes that seemed of similar strength. I even heard a quake underwater back during my dive career ! Big Boom that I felt right through my whole body.  The other diver and I thought the Navy bombed us but not a boat in sight with clear weather. 

[vox_mundi]

11% Chance of Another Huge Earthquake in Southern California, Scientists Say
https://phys.org/news/2019-07-chance-huge-earthquake-southern-california.html

The odds that Southern California will experience another earthquake of magnitude 7 or greater in the next week are now nearly 11%, according to preliminary estimates from seismologists.

And the chances that a quake will surpass the 7.1 temblor that struck near Ridgecrest on Friday night are roughly 8% to 9%, said Caltech seismologist Lucy Jones.

More likely is that the Owens Valley will experience another temblor of magnitude 6 or greater. The odds of that are slightly greater than 50-50, Jones said. And more quakes of magnitude 5 or greater are a near certainty.

"It would be extremely unusual if we didn't have another 5" over the coming week, Jones said.

... the fault is now likely to be 25 to 30 miles long.

"The fault is growing," Jones said.

[TerryM]

Terry, It is about 250 miles from here to Ridgecrest and it was strong here with roll lasting about twenty seconds. I moved rooms and aligned with the roll. I pointed to the direction of the quake,
and guessed correctly. I can think of three other quakes that seemed of similar strength. I even heard a quake underwater back during my dive career ! Big Boom that I felt right through my whole body.  The other diver and I thought the Navy bombed us but not a boat in sight with clear weather.

Bruce


The Sylmar Quake in '71 was the worst I've experienced. I was in Riverside and a wall with a gas heater was twisting in and out of "S" shapes as flames and sparks escaped the enclosure. My first thought was that my house would burn down, followed closely by thoughts of the fortune I would make repairing broken pipes.


Neither proved to be the case.


The rubber "Band Seals" developed for clay sewer lines proved flexible enough to withstand the strain (though for years later the mis-positioned pipes caused blockages, and toilets could be found with handfuls of sand in the tanks,) while the metal pipes either bent a small amount or popped their retaining clamps.


A Veterans Hospital closer to the epicenter collapsed and a few overpasses crashed down, but the 6:01 AM timing meant that few were on the road.


My Riverside home has since been earthquake hardened, and on the advice of an Air Force damage consultant I dropped my earthquake insurance a few years later.
Sylmar was only rated at 6.5, but with 65 deaths and freeway closures it seemed to cause a fair amount of damage.


I had no idea that you were so close to Ridge Crest. My few trips there were always from and back to Las Vegas.


Hope the oinkers weren't too upset and that there was no damage to house or farm.
Terry 

[Tor Bejnar]

The Great Alaska earthquake of 2021
http://www.volcanocafe.org/

This article suggests the topic "Earthquakes and not-climate change", and puts the recent Alaskan earthquake into perspective.

Alaska can be a shaky place. [10 days ago], at 10:15pm local time on Wednesday, there was an M8.2 earthquake in the region. It was the largest earthquake on Earth since the M8.3 in Chile in 2015. ... (There have been two other M8.2 shakes since 2015, one in 2017 in Mexico and one in 2018 in Fiji ...) The massive earthquake did little damage. But was this an exceptional event? Or a sign of things to come, so soon after the Anchorage earthquake [in 2018]?
...
All but one of the [Earth's] 15 M8+ earthquakes since 2000 are on the edges of oceanic plates, and are located in subduction zones. Earthquakes of this size outside of subduction zone are very rare. The outlier was in Peru in 2019, an M8.0 120 km below the Andes. This is still in a subduction zone, but is much further downstream and is far underneath the continent.
...
[A map showing location and year of major Alaskan earthquakes shows several pairs of earthquakes, location-wise, fairly evenly spaced along the Aleutian Islands.]
...
These pairings show a pattern. The largest earthquakes (M8+) are repeat offenders, with recurrence times between 30 and 80+ years.
...
There are no final words on earthquakes. They have happened before and will happen again. Some areas of the world have been hit hard: Indonesia and Japan come to mind. Others have had time off. But in a way, that can be more dangerous. They will come again, and people may no longer be sufficiently prepared. This event, large but without damage, was a useful warning sign. The years of quiet may be coming to an end. Other places are more at risk, especially places such as China and Pakistan which similarly have not seen anything on this scale for 50 years or more, but have had them before. After the tsunami warning has passed, the earthquake warning should remain.

[kassy]

Off topic post removed. It is not a general Earthquakes thread.

[Jim Hunt]

Off topic post removed. It is not a general Earthquakes thread.

Is there a "general Earthquakes thread"?

[HapHazard]

I don't see why we'd need one, at least not in the cryosphere section.

[kassy]

Nor here. And no there isn´t one.