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More than 19k undersea volcanoes discovered
- dataflow 3y ago> In 2005, the nuclear-powered USS San Francisco collided with an underwater volcano, or seamount, at top speed, killing a crew member and injuring most aboard. It happened again in 2021 when the USS Connecticut struck a seamount in the South China Sea, damaging its sonar array. How in the world does a submarine going at < 40 mph not detect that it's running into a mountain? Why are light, radar, and sonar still not enough to detect obstacles that big?
- miketery 3y agoMaybe they’re off for stealth?
- vkou 3y agoYou can't navigate by light, and if you are trying to be stealthy, you won't be running active sonar. Radar doesn't work well underwater.
- perfmode 3y agohow deep do submarines cruise?
- dragonwriter 3y agoThe San Francisco collided with the seamount at 160m depth.
- dragonwriter 3y ago> How in the world does a submarine going at < 40 mph not detect that it's running into a mountain? Seamounts don’t give off active emissions (except maybe if they are erupting), and subs usually use passive hydrophones (which rely on the active emissions of targets), not active sensors when operating underwater to avoid detection. Navigation is done by charts using inertial navigation alongside dead reckoning. Hitting a mountain is generally because the mountain wasn't on the chart being used, though in principle in could also be due to an error in positioning (with inertial navigation, that should be much rarer than with dead recknoning alone, but its not impossible.) (In the case of the San Francisco, for instance, other charts had a notation of "discolored water" which suggested a probable seamount, which the investigation noted should have been transferred to the chart in use, but was not.) > Are light, radar, and sonar still not enough to detect obstacles that big? Radar is useless underwater, light would also be useless for spotting anything in time to react at speed, and sonar isn’t routinely used because it compromises stealth.
- throwaway8503 3y ago>> Are light, radar, and sonar still not enough to detect obstacles that big? > Radar is useless underwater, light would also be useless for spotting anything in time to react at speed, and sonar isn’t routinely used because it compromises stealth. Any people with knowledge in the field care to comment on whether it's feasible for a light (em?)-type, active, near-range detection system to work? It seems to me the basic problem is: - enough energy to get a signal at a range sufficient to move around any detected obstacles - high enough dissipation in water to minimize range at which detection by external sensors is possible
- iancmceachern 3y agoThe light transmission through the water, it's cloudiness, is just way to variable for something like this to work constantly, reliably.
- throwaway8503 3y agoWouldn't the cloudiness itself be a signal? Presumably it's essentially clear of suspended particles, most of the time.
- iancmceachern 3y agoA signal of what?
- throwaway8503 3y agoSomething solid ahead To clarify: I mean that, generally speaking, the presence of 'cloudy' water would presumably signify that the seafloor was close. In the open ocean, maybe a sea mount is surrounded by essentially a cloud of particles. Edit: I think your reply made the thread reach maximum depth, so I'll end it here.. I should do more reading on the topic.
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- gonzo41 3y agoMost underwater travel is done via dead reckoning. Like flying a plane with no windows. You're only as good as your maps and instruments.
- mywacaday 3y agoHow viable would drones travelling in front of the sub like the whiskers in the TV show seaQuest DSV
- capableweb 3y agoOne of the main features of military submarines is being undetectable by others, to various degrees. This include visual, audio and movement detection. Drones would probably make all of those three factors worse and make the submarine more detectable, than without a drone travel in front.
- hilbert42 3y agoThe USS San Francisco crash-type problem was discussed some while ago on HN. At the time I questioned how this could happen when one would expect a submarine of that sophistication to be equipped with both sonar and gravity detection. Detecting changes in gravity is common practice in mining surveys (ores often have higher densities) and geological work, so for me why the sub collided with the seamount remains a mystery. I cannot believe subs of this class don't have such detection on board so could someone more knowledgeable about the subject than me provide an explanation.
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- DrBazza 3y ago> How in the world does a submarine going at < 40 mph not detect that it's running into a mountain? Two things: first US submarine, second "South China Sea". I suspect the sonar was off "for reasons".
- nahnahg 3y agoBecause they are too stupid to use large aperture (and pressure stabilized) plain old optics with CCD sensor array. I assume this is done actually. If fish can do it at the greatest depths then...
- indymike 3y agoEasy way to not be found is to not emit energy be it sound, heat, light, radio frequency, etc... until we discover a passive sensor that works underwater that can see static objects that may not emit energy, seamounts and other things that change the map are occupational hazards for submariners.
- SV_BubbleTime 3y agoIn what might be a stupid question… Do underwater volcanos release CO2 when erupting? I assume it would be yes, and that eventually bubbles would reach the surface. But, could imagine a scenario where the gas is absorbed before reaching the surface?
- edmundsauto 3y agoThe San Francisco struck it at 160m depth, I am also curious to this question. 1km, sure I doubt we see bubbles - but 160m is not as deep (and the bubbles would get bigger in volume as they rise). Great question, does anyone know?
- ycombinete 3y ago“From the ocean surface to depths of about 500 meters CO2 would exist as a gas and would tend to rise in the water column, since it is less dense than seawater. Between 500 meters and 2,700 meters CO2 would exist as a liquid, but one that is still lighter than seawater and would thus also rise in the water column. At depths up to 2,700 meters CO2 will create a rising plume and dissolve into the surrounding seawater relatively quickly. At depths deeper than 3,000 meters the weight of the water column compresses the liquid CO2 and it becomes denser than seawater and sinks slowly to the seafloor.” [0] So yes, even at normal temperatures for that depth C02 would be a gas; definitely so at volcanic temperatures! [0] https://maritime-executive.com/features/ocean-storage-of-co2 https://maritime-executive.com/features/ocean-storage-of-co2
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- wilg 3y agoI’d have been impressed with just one!
- Xelom 3y agoThen does this mean these volcanoes will slowly shrink the size of the ocean which might contribute to raising sea levels on top of melting glaciers?
- pulvinar 3y agoIt would be extremely unlikely. Instead, it should be close to equilibrium, with as many eroding away as being created.
- 1propionyl 3y agoWouldn't erosion tend to lag exposure by something like an order of magnitude or five? Geological time vs climate time. That said, I'd also point out that most of these are deep enough we wouldn't see them exposed even if ocean levels dropped a meter worldwide.
- codybontecou 3y agoWouldn't it just displace the water?
- theelous3 3y agoYes? That is exactly the commenters concern. Fill a bowl to the brim with water, throw a ball in. It spills over the edges of the bowl by "just displacing" the water.
- colechristensen 3y agoNo. Land moves around, raises and lowers, plates crash lifting mountains and subduct continents under each other so stuff moves, but stuff goes up and down at the same time. Sometimes the land sinks, sometimes it's pushed up, but these geological processes happen on geological time. Sea level rise is a concern within a few human generations. These are just much different time and volume scales.
- louthy 3y agoSurely the magma, once cooled, would take less physical space than when hot?
- alejohausner 3y agoHere is the data: https://zenodo.org/record/7718512 https://zenodo.org/record/7718512
- whitemary 3y agoIs every seamount a volcano?
- Tepix 3y agoFrom tfa: "the team can detect seamounts just 1100 meters tall" This really gives you an idea how poorly the ocean floor is mapped.
- Ekaros 3y agoThat is quite many, if you start to think spacing them, 19000km if they were 1km apart on average... Then again, there is lot more fault line distance on Earth.
- jl6 3y agoDo these volcanoes really have steep/craggy dramatic slopes like the image suggests? I remember being disappointed to find that the Mariana Trench didn’t have looming near-vertical canyon walls, but rather had a relatively tame slope.
- DrBazza 3y ago> Do these volcanoes really have steep/craggy dramatic slopes like the image suggests? Probably not many. They will have formed slowly at plate boundaries such as the mid-Atlantic ridge, then moved apart over millions of years, then very, very, slow erosion. > I remember being disappointed to find that the Mariana Trench didn’t have looming near-vertical canyon walls, but rather had a relatively tame slope. One of my favourite books mentioned that you could easily drive a car to the bottom of the Marianas trench if it were dry (https://seabedhabitats.org/2015/08/26/book-review-mapping-the-deep-by-robert-kunzig/ https://seabedhabitats.org/2015/08/26/book-review-mapping-th...).
- marcellus23 3y agoWow, I did some googling and found this cross-section of the Mariana Trench. Was not expecting this at all (bottom of the page, figure 4): https://mason.gmu.edu/~bklinger/deeptrench.html https://mason.gmu.edu/~bklinger/deeptrench.html
- Scubabear68 3y agoIt has always boggled my mind that military subs run around under the water largely blind, due to the fact that using active sonar would give their position away, and passives are going to miss many things like this.
- richardfey 3y agoA map would have been nice there