The opening and closing of ocean basins has had a dramatic influence on climate and biological evolution over Earth's history. These processes occur roughly every 500 million years, but how they're initiated—particularly in the case of continental rifting to form the seafloor of new ocean basins—remains enigmatic. To understand the beginning stages of continental rifting, Ligi et al. performed geophysical surveys and collected seafloor samples from aboard the R/V Urania in the Red Sea, which rests atop one of the most prominent modern continental rift zones. The Red Sea Rift is still in the process of rifting, so it includes a span of oceanic crust formed over the past two million years. The data suggest that new seafloor forms initially as an intense pulse of convection-driven mantle upwelling breaks through the continental crust, rapidly declining as convection of the mantle weakens with a widening rift. This process is pulling Africa apart from Arabia to form a new ocean, just as it may have contributed in the past to the breakup of supercontinents.
Geology 39, 1019 (2011).
So what originates the "intense pulse ??
Lithospheric Thinning Beneath Rifted Regions of Southern California
ABSTRACT
The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere.
ravelling on the CSIRO vessel Southern Surveyor the scientists discovered the islands through detailed seafloor mapping and by dredging rock samples from the steep slopes of the two islands, now in water depths of over 1.5km.
"The sunken islands charted during the expedition have flat tops, which indicates they were once at sea level before being gradually submerged," said Dr Whittaker.
Collecting rocks from the abyss more than 1.5km below the surface was not easy, but the geologists managed to retrieve hundreds of kilograms and unexpectedly found rocks that showed the islands had not always been underwater.
Cretaceous period is debatable. 1.5 kilometer depth is impressive.
I have witnessed this several times over the years- including the events I discovered via a quick Google search HERE
This is a very real phenomenon, and was so pronounced this morning that my first thought was a serious explosion rumbling the ground in the distance. It shook the building I was in. I spoke to relatives immediately after that, and from clear across the county some 20 miles away they felt it at the same time.
Oddly, seismologists claim to detect nothing on their charts, which I find bizarre, for if some event that shakes an entire region of a state is invisible to their equipment, what good is it?
I got to thinking about the reading I've done here, on how electrically active the crust and core of the planet may well be, and posit this question to you: is there a chance that this effect is caused by subsurface lightning of some sort, or perhaps another geomagnetic/energetic phenomenon?
The fact that it has occurred for centuries eliminates the tinfoil hat military testing hypothesis.
I'm very interested to get your thoughts on this--
Kindest regards--
phyllotaxis
Lloyd
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
... Although reported regularly at points up and down the Eastern Seaboard, Seneca guns seem particularly concentrated off the Carolinas. To date, no satisfactory scientific explanation for the phenomenon has been found. The name "Seneca Guns" seems to come from Seneca Lake in upstate New York, where the sounds are often heard. In 1850, James Fenimore Cooper (author of "Last of the Mohicans") wrote a story, "The Lake Gun," describing the phenomenon, which seems to have popularized the term. ... The "guns" seem connected to similar phenomena heard in different parts of the world, such as the "Barisal guns" in parts of India and Bangladesh, the "uminari" of Japan and the "mistpouffers" on the coast of the Netherlands and Belgium. ... On November 18, 2009 at 8:21 pm David Peacock wrote: Regarding the Seneca Guns, Hi, I'm a resident of Southport, and Boiling Spring lakes, NC. I have often heard the Seneca Guns down here. On one occasion back in the early 90′s i was working at the local Firestone garage in Southport. There at the garage, we had 3 large bay doors that we had closed due to the cooling weather. On that particular day we got hit with the Seneca Guns, three in a row. I remember seeing the doors literally move in and out due to the pressure of the wave. I realized then it was an atmospheric phenomena, literally a giant pressure wave. I have also noticed when they hit, it is almost always a day when the humidity is relatively low for that time of year. Anyway thank you for the article. I enjoyed reading it. Regards, David peacock
flippinrocks
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
Sounds like the reporter is vaguely and unknowingly is describing where giant thunderbolts discharged. Then, just like the captured lightning in arcylic blocks spontaneously re-discharging 20 minutes later, scaled up to a planet 2000 years later. Allthough unlike the acrylic blocks, the Earth is under constant 'bombardment' from the Sun. The acrylic block would seem to be the upper atmosphere and the Earth.
ElecGeekMom
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
Do they tend to happen at a particular time of day? time of year? time in the solar cycle?
MattEU
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
do the areas of open water have a sudden and unexplained rise in level before, during or after these events?
phyllotaxis
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
I've never read of any water events coincident to the effect, nor am I familiar to any common time- aside from my recollection it has been daytime every time I've read of it and experienced it.
Sparky
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
These describe sonic booms, don't they?
Pre Mach 1 history, maybe meteorites or clear atmosphere lightning/thunder?
phyllotaxis
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
Perhaps- though I would expect that such phenomenon would occur in other places too, as opposed to the seemingly few places it is recorded...
Such a strange thing--
jjohnson
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
Sonic booms and thunder can both register on seismometers. Many universities have a department of seismology or instruments of that type that record seismic events. You might try making a few phone calls to local higher ed institutions and see if they can correlate an event on their equipment with the time frame you heard the phenomenon.
About 2 years ago a pair of F-15's were scrambled from Portland Oregon to investigate an intrusion into a temporary "no-fly" zone set up in Seattle for a visit from the President. As usual, they hurried north above mach 1, and laid down a sonic boom carpet almost the entire way. The boom was heard widely throughout Seattle, and numerous phone videos were aired on the evening news, of course. It was mentioned that such disturbances can be picked up on ground-measuring equipment, and were, as this is a seismically dangerous place to live and the U. of Washington and other agencies monitor constantly at many locations. It's be worth asking around about in your area.
Jim
phyllotaxis
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
That was my firs thought too- but in the story linked at the top of the original post, the newspaper contacted the Wilmington office of the national weather service, and they were told there was no registered earthquake at the time of the incidents. The day before, in Virginia, there was a Magnitude 1.8 recorded, but nothing on the day of the event in NC. In 2010, the news article recording that event specifically mentions the Geological service being contacted and them saying there was no event. HERE is that article
The mystery remains...
kell1990
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
Do seismographs measure relative motion or absolute motion? I'm pretty sure they measure relative motion. Is it possible that some of the sonic phenomena we hear are caused by major "ripples" in the earth's crust, which could be the source of the types of sounds being reported?
Imagine a long-wavelength wave moving across the water. That is the type of movement that I think might be consistent with both the reported movement on land, yet the lack of registeration on siesmographs.
What could cause such an anomolous movement of the earth's crust? An ourside influence. Which outside influence? The Sun and the cosmos. How? By the manipulation of the earth's magnetic field, which in turn causes the ferric materials in the earth's crust to react, according to flux levels. The earth and everything on it moves simultaneously in this situation.
If this conjecture is right, then there should be corresponding increases in the temperature of the ionosphere and the stratosphere as these waves of EM current move through the earth's space.
Drethon
Re: "Seneca Guns" in Southeastern Carolinas- it's happened a
Seismographs have a weighted object on a spring typically, more modern versions may use electronic accelerometers. The measurement occurs when the object on the spring stays relatively still while the rest of the equipment moves around it, or in accelerometers I believe a compression occurs when the "free standing" object inside tries to stay still while everything else moves. The two ways I can think of to prevent movement are a movement slower than the resistance of the material (ex move slowly and the spring will stay with the machine) or gravitational acceleration which affects both the stationary and moving parts.
To produce a booming noise, I don't think either cases are relevant to normally understood situations.
