[HN Gopher] Earthquake in Japan yesterday may have shifted land ...
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Earthquake in Japan yesterday may have shifted land 1.3 meters
Author : ronyclau
Score : 99 points
Date : 2024-01-02 11:55 UTC (11 hours ago)
(HTM) web link (www3.nhk.or.jp)
(TXT) w3m dump (www3.nhk.or.jp)
| sandworm101 wrote:
| The amount of energy released in such events boggles the mind.
| Shifting cubic-kilometers of rock, in this case several hundred
| or even thousands of cubic-kilometers, even a few inches requires
| more energy than all the worlds nukes many times over. We live
| atop an immense heat engine, every little vibration of which
| could power our entire civilization for years.
| cm2187 wrote:
| It's even harder than harvesting lightnings.
| sandworm101 wrote:
| I'm not sure about that. Drill some holes, pump some water,
| and geothermal power straight to the grid can be done.
| Harvesting lighting would require innumerable towers and even
| would require some trickery to get it hooked up to our power
| grids.
| borgunit2 wrote:
| That's not kinetic earthquake energy, though.
|
| I think in an apples-to-apples comparison, you would need
| to attach some kind of device to absorb the kinetic energy
| from the fault.
| rzzzt wrote:
| A building-sized piezo crystal?
| lawlessone wrote:
| Country sized.
| squirtle24 wrote:
| Or one clock tower and a flux capacitor...
| cm2187 wrote:
| ...and wait for the next major earthquake to even test it.
| barbariangrunge wrote:
| A friend, back when he was a physics student, looked into
| harvesting lightning.
|
| He calculated that it wasn't economically viable: tons of
| wattage, but for such brief timespans, that it doesn't
| actually amount to that much on a comparative scale. The cost
| of building the collectors and transporting the electricity
| (from ocean platforms) was much higher than the cost of using
| other energy sources. Iirc. It wasn't exactly a serious
| investigation by a team of engineers, but I basically trust
| his conclusion.
|
| Maybe it will be more attractive in the future after we stop
| using hydrocarbons?
| kulahan wrote:
| I know embarrassingly little about electricity, but
| wouldn't this also likely require significant advances in
| semiconductors to even be feasible?
| IKantRead wrote:
| I've always found it fascinating that geophysicist and earlier
| advocate for Bayesian methods, Sir Harold Jeffreys, _didn 't
| believe_ in continental drift and plate tectonics because he
| felt there was no known source of energy on the Earth massive
| enough to explain this movement. [0]
|
| He remained an opponent until death (at which point continental
| drift was _widely_ accepted) which is both a testament to the
| literally unbelievable energy behind seismic activity and the
| importance of _updating_ your Bayesian priors as you gain new
| information.
|
| 0.
| https://en.wikipedia.org/wiki/Harold_Jeffreys#Opposition_to_...
| thehours wrote:
| Actually the lesson I take away is the importance of not
| having a 0% (or 100%) prior, since it leaves no room to
| update with new information.
| roenxi wrote:
| It is also suspicious because it means someone has assigned
| a 0% prior to their being insane or in some sort of
| Plato's-cave scenario - which is hard to justify.
|
| The minimum possible Baysian prior is a base rate of "my
| senses are just not picking up reality and/or my memory is
| catastrophically compromised and/or I cannot process logic
| right now due to some reason" which while low is never
| going to be 0%. There are too many known ways for human
| brains to fall over. 0% priors are unjustifiable.
| throwup238 wrote:
| Another great illustration of Planck's law:
|
| _> Max Planck, surveying his own career in his Scientific
| Autobiography, sadly remarked that "a new scientific truth
| does not triumph by convincing its opponents and making them
| see the light, but rather because its opponents eventually
| die, and a new generation grows up that is familiar with
| it."_ -The Structure of Scientific Revolutions
| blackbear_ wrote:
| This is actually such a great insight. That's why we also
| need new generations of politicians and management every so
| often to keep the wheel of progress rolling. And,
| incidentally, why I think that developing anti-aging
| technology is not a good idea.
| cozzyd wrote:
| I've always found it fascinating that the guy who came up
| with the theory (Wegener) died in on the ice sheet in
| Greenland while attempting to resupply a research station.
| Having spent some time on the Greenland Ice Sheet at Summit
| Station, life on the Greenland ice sheet is much more cushy
| nowadays...
| barbariangrunge wrote:
| I think we sort of have the tech to use geological energy, but
| I imagine the hardest part is not having your equipment
| destroyed all the time by quakes? You'd probably want to put
| your collectors deep underground where there's more activity
| sandworm101 wrote:
| At a theoretical level, it could be done with ropes. You
| don't need to wait for earthquakes. Setup two anchors on
| either side of a fault. String ropes between them. As the two
| plates slowly more, the stretching ropes can be tied to
| generators. Totally theoretical but, no new physics is
| required to extract energy from two slowly moving things.
| throw0101d wrote:
| Australia updated its latitude and longitude somewhat recently
| because of continental drift:
|
| > _The Geocentric Datum of Australia, the country's local
| coordinate system, was last updated in 1994, and Australia is now
| about 1.5m further north-north-east (or, to give the metric used
| in a BBC infographic: about the height of a kangaroo)._
|
| * https://www.theguardian.com/science/2016/aug/03/mind-the-gap...
|
| * https://www.ga.gov.au/scientific-topics/positioning-navigati...
|
| * https://www.australiangeographic.com.au/topics/science-envir...
|
| To anyone working in the GIS industry: how would one go about
| doing a 'mass update' of locations of an entire country in maps
| and firmware and such?
| dboreham wrote:
| Locations inside a country (e.g. plat map boundaries) don't use
| latitude/longitude.
| taeric wrote:
| They didn't used to. And, of course you are correct that
| survey markers are to landmarks. But, more and more people
| are using data from online mapping services, that largely
| think they can store locations in lat/lng. People seem to
| trust that as "the UTC of location data."
|
| That said, those can be just as fraught, no? Since movement
| will not be fully uniform for the entire continent? And
| landmarks aren't static things, either? I'm curious how
| landmarks are done to preserve this, long term?
| tmm wrote:
| > And landmarks aren't static things, either? I'm curious
| how landmarks are done to preserve this, long term?
|
| At least in the US, the people in charge of this (the
| National Geodetic Survey) take movement into account.
| This[1] is the datasheet for the reference monument nearest
| my house. It has data for 3D velocity of the reference
| point. VX = -0.0150 m/yr northward
| = 0.0040 m/yr VY = -0.0008 m/yr eastward =
| -0.0148 m/yr VZ = 0.0030 m/yr upward =
| -0.0002 m/yr
|
| I'm not sure what the difference is between VX/VY/VZ and
| northward/eastward/upward, but those numbers are bigger
| than I thought they'd be. 15 mm/yr seems like a lot!
|
| The official coordinates get updated from time to time, and
| in-between, perhaps you're supposed to adjust your
| measurements using that movement data (IANAS)? If there is
| a significant measured change in location due to an
| earthquake, I'm sure that data would be included in the
| monument datasheet or a new set of coordinates would be
| published.
|
| FWIW, I went looking to see when the last earthquake was
| here in Maryland and it turns out there was one today[2].
|
| [1] https://www.ngs.noaa.gov/cgi-
| cors/CorsSidebarSelect.prl?site... [2]
| https://www.abc27.com/news/top-stories/2-3-magnitude-
| earthqu...
| eesmith wrote:
| Some places use an encoded lat/long.
|
| Open Location Code - "Google has shown practical usage of
| plus codes for addressing purposes in Cape Verde,[10] parts
| of Kolkata[11] and Kolhapur[12] in India, and the Navajo
| Nation in the United States.[13]" -
| https://en.wikipedia.org/wiki/Geocode .
| https://freethoughtblogs.com/singham/2023/12/24/using-olc-
| co... says a friend of his sent an OLC coordinate to get to a
| place in Carmel-by-the-Sea, California, which (infamously?)
| has no street numbers.
|
| What3words - "This population had "no consistent addressing
| system" until May 2016 when Mongol Post started using a
| geocoding system provided by what3words." -
| https://en.wikipedia.org/wiki/Mongol_Post
|
| Over time (centuries?) the named coordinate will no longer be
| valid as the location is no longer near enough to that
| lat/long.
| taeric wrote:
| I'm also curious if anyone has a good article to read on how
| this is managed. My guess would be that you have reference
| points and sets of nearby things that are recorded relative to
| the closest reference point. As noted in the sibling, your plat
| map is likely set against a local landmark. (Though, even
| there, they often also include the lat/lng of where it is
| expected to be found.)
| gwright wrote:
| This is a good example of why capturing coordinates in a
| local spatial reference system may be better than capturing
| coordinates in a global spatial reference system.
|
| Global coordinates of a place of interest will drift relative
| to a global coordinate system but remain stable relative to a
| local coordinate system. This article illustrates that
| "stable" is not the same thing as unchanging in the presence
| of 7.5 earthquakes.
| chrismorgan wrote:
| Australia's geocentric datum is pretty boring, because
| Australia's tectonics are pretty boring. We just don't get
| large earthquakes. So the GDA94 - GDA2020 update is actually
| pretty minor.
|
| If my understanding is correct, the 1.8m difference sometimes
| talked of between ITRF92 and GDA94 by 2020 is actually
| irrelevant so long as you do proper projection of your
| coordinates, which you _should_ , but some things don't--and so
| tweaking your reference point from time to time to compensate
| is pragmatic (in part because it lets people skip deformation
| models where a metre or so of accuracy is adequate, so temper
| my "should"). The GDA94 - GDA2020 update is more about certain
| changes in ITRF1992 - ITRF2014 (~9cm changes in ellipsoidal
| heights), and local crust deformations. Mass updating from
| GDA94 to GDA2020 is an easy reprojection.
|
| In saying GDA94 is actually fine as far as continental drift is
| concerned: the thing most people don't realise is that all of
| these coordinate systems are actually _time-dependent_
| transformations: they've got forecast continental drift baked
| in. So later datum updates just need to record what _actually_
| happened, if it was different enough (which it will be in
| places).
|
| Now real earthquakes--they make things much more interesting. I
| like what https://www.linz.govt.nz/guidance/geodetic-
| system/coordinate... says:
|
| > _Some earthquakes, such as those of the Canterbury earthquake
| sequence starting in 2010, have caused metres of movement.
| Where this has happened we have updated the coordinates rather
| than simply include the movement in the deformation model. This
| is necessary as otherwise the coordinates will not be accurate
| enough for many applications. The deformation model still
| includes the earthquake deformation, but it is applied in
| reverse to transform coordinates for dates before the
| earthquake._
|
| The deformation model page
| <https://www.linz.govt.nz/guidance/geodetic-
| system/coordinate...> is also rather interesting, giving
| details of when they've released new deformation models,
| including both forward and reverse patches due to earthquakes,
| and it's _messy_. I haven't thought too deeply about the
| reverse patching technique (this isn't a domain I work in) but
| I don't think I like it (though it may be pragmatic) because it
| messes with epoch-era NZGD2000 points, seems to undermine the
| purpose of a datum unless you have recorded the coordinate
| times as well (rather than merely transforming to the epoch,
| which has now been spoiled). Did have a fun chat with a
| telecommunications field worker that I happened to meet when I
| was in New Zealand in 2021, who had a lot of interesting
| experience after the 2016 Kaikoura earthquake. Lots of stuff
| I'm not used to thinking about, coming from boring old
| Australia.
| bee_rider wrote:
| Hi from New England, middle-of-the-plate buddy. In fact, it
| had never occurred to me that the mapping of parts of the
| ground to, like, latitude-longitude could be time dependent,
| haha. I guess this could make a big difference in surveying.
| blacksmith_tb wrote:
| For most surveying wouldn't the the relative, nearby points
| be shifting together equally?
| johncalvinyoung wrote:
| not in California, Iceland, or Japan!
| badcppdev wrote:
| This is a very sad example of land movement and it's a tragedy
| that people have died in the aftermath and recovery effort.
|
| But it's also an important reminder that our super accurate GPS
| measurements are not 100% reliable over time. The earth moves.
| Either in jumps like this or fairly constantly if it's somewhere
| like Australia [0]
|
| 0 -https://www.nytimes.com/2016/09/24/world/what-in-the-
| world/a...
| dataflow wrote:
| I'm confused, how does moving 2.7 inches a year translate into
| 656 feet over 25 years? Was it moving tens or hundreds of times
| faster a few decades ago?
| badcppdev wrote:
| I assume that should be 6.56 feet or some similar
| miscalculation converting from metric to imperial
| measurements
| throw0101d wrote:
| > _6.56 feet_
|
| Statute feet or survey feet?
|
| * https://www.nist.gov/pml/us-surveyfoot
|
| * https://oceanservice.noaa.gov/geodesy/international-
| foot.htm...
|
| *
| https://en.wikipedia.org/wiki/Foot_(unit)#U.S._survey_foot
| burkaman wrote:
| Basically, before 1994 the official Australia coordinate
| system was not optimized for GPS, which was not common when
| the system was developed, and so didn't exactly align with
| global coordinates. The 656 foot change was mostly about
| that, not about tectonic changes.
|
| AGD is Australian Geodetic Datum of 1984 and GDA94 is
| Geocentric Datum Of Australia 1994.
|
| > The AGD provided a reference system that best fit the shape
| of the earth in the Australian Region but its origin did not
| coincide with the centre of mass of the earth. National
| datums were commonly non-geocentric before satellite based
| navigation systems were established in the early 1970's. The
| distance between the origin points of GDA94 and AGD is
| approximately 200 metres. When the coordinates of a point on
| the Earth's surface are converted from AGD to GDA94 this
| translates to a coordinate difference of approximately the
| same amount. The difference varies slightly depending on
| where you are in Australia.
|
| - https://www.icsm.gov.au/datum/australian-geodetic-
| datum-1966...
|
| > Previously, a change of about 200 metres occurred in the
| year 2000 when Australia shifted from the Australian Geodetic
| Datum 1984 (AGD84) to the Australian Geocentric Datum 1994
| (GDA94).
|
| - https://www.dmp.wa.gov.au/News/Geocentric-Datum-of-
| Australia...
|
| Nowadays you can use the Australian Terrestrial Reference
| Frame, which is time dependent and automatically adjusts to
| compensate for tectonic movement:
| https://www.icsm.gov.au/australian-terrestrial-reference-
| fra....
| samstave wrote:
| > _reminder that our super accurate GPS measurements are not
| 100% reliable_
|
| Lockheed solved this with their super sensitive Magnetic Field
| ' _GPS_ ' device - which they claim if for having 'GPS'
| accuracy for aircraft and ships nearly 100% based on the
| localized magnetic signature of the earth - but we all know
| these are actually built for subterranian/submarine environs
| where space based GPS no cut it. Can't navigate Agartha without
| it.
|
| https://www.gpsworld.com/quantum-magnetometer-senses-its-pla...
|
| I do wonder how much major earthquakes affect the finer
| signature of the magnetic fields?
| KeplerBoy wrote:
| How is this solved?
|
| The surface of the earth just shifted in a highly non-linear
| and non-uniform way. Places are not at the same coordinates
| or at the same distances from each other they were last week.
| samstave wrote:
| Read the link. The quantum magnetic locator doesnt use GPS
| satellites, so the "our GPS is not 100% accurate" is solved
| by the magnetic quantum thing... its just not available on
| _ _your_ _ smartphone.
|
| Re-read my post, I believe that the real use of Lockheeds
| Quantum GPS is for subterranian and submarine navigation
| more than it is for aircraft - hoever, if we can map the
| magnetosphere of other planets, say, mars, then this could
| be a non-satellite-dependant GPS for any body in space
| where we know the magnetic signature based on probes...
| although said probes could also double as GPS satellites
| for the planet they are probing should we add such
| equipment, it would seem.
| KeplerBoy wrote:
| But the problem is not the accuracy, it's the temporal
| stability. GPS is accurate enough, but it's no good if
| the physical locations shift over time.
|
| Most people need an up-to-date map, not just a location
| on a map.
| shagie wrote:
| Related - Farmers 'crippled' by satellite failure as GPS-
| guided tractors grind to a halt 181 points 8 months ago
| 150 comments
| https://news.ycombinator.com/item?id=35643705 --
| https://www.smh.com.au/national/farmers-crippled-by-
| satellit...
| bobthepanda wrote:
| GPS is only accurate up to 16 feet, and unless you are
| very close to an earthquake or other deformation source
| probably everything around you has moved by the same
| amount.
|
| Most people only use GPS for local navigation.
| KeplerBoy wrote:
| GPS is much better than 16 feet these days.
|
| Nobody asks google maps for instructions how to move 10
| miles southwest. We ask it to provide a route to a
| specific latitude and longitude, that's global navigation
| and that, of course, doesn't work if the place you want
| to get to has gotten new coordinates overnight.
| bobthepanda wrote:
| That 16 ft figure is provided by the government.
| https://www.gps.gov/systems/gps/performance/accuracy/
|
| And of course, satellite navigation is worsened by the
| urban canyon of buildings, terrain, trees etc so super
| accurate navigation also uses local cell towers, which
| are also shifting by the same magnitude and direction as
| you and your local destination.
|
| Ultimately people only really need to get to the rough
| city block of where they need to be, and so as long as
| buildings are not shifting hundreds of feet a year it is
| mostly not noticeable.
| pxeboot wrote:
| From that source:
|
| > GPS-enabled smartphones are typically accurate to
| within a 4.9 m (16 ft.) radius
|
| Smartphones were typically optimized for speed and
| battery life, not accuracy. Now that Multi-Band GPS is
| available on high end smartphones, they tend to be more
| accurate.
| WJW wrote:
| Also almost every smartphone I know of has acceleration
| sensors and can do Kalman filtering of the GPS position
| to achieve a much higher accuracy in practical use, even
| if the individual measurements are only accurate to ~5
| meters.
| samstave wrote:
| They add fuzz to RSSI algos due to accelerometers trying
| to predict direction ofmotion for telemetry aiming.
|
| swarm that on that backend with GPS tlemetry and typical
| rssi from cell towers, and the IMEI - and you have
| precise targets... with bios on the tracker (phone) -
| cams, gait, finger, face, voice, face... May as well
| start developing smart fabric... Oh wait...
|
| :-)
|
| Cyberpunk is dystopian by mr(crisper)DNA (TM)
| samstave wrote:
| Could even use this as a revers GLOBAL ORBITING SYSTEM
| [GoS] - Whereby a single satellite|probe dispels a lander
| to a planet with the Quantum Magnetic Cannister, and that
| QMC signals its global location to the satellite
| launcher, and the satellit can extrap its location based
| on the absolute location of the ground guys... (might
| need more than one ground magnet-moles?)
|
| How can this be measured? Can fluidx3d do martian
| magnetics? [0]
|
| --
|
| [0] https://github.com/ProjectPhysX/FluidX3D
|
| ---
|
| EDIT: "Mars does not have a magnetosphere"
|
| ELI5: "how do electronics work when there is zero
| magnetic field around them? A complete antimagnetic
| environ?"
|
| I've never heard any mention about making any electrical
| device work on a planet (such as mars) in a complete
| magnetically dark location?
|
| How is there gravity on mars if there is no magnetic
| field for a planet, and how can mass, the size of a
| planet not produce magnetism/gravity if its not made of
| iron-sh (the RED of the planet)
|
| ELI5, please.
| amluto wrote:
| > But it's also an important reminder that our super accurate
| GPS measurements are not 100% reliable over time. The earth
| moves.
|
| This is IMO an odd statement. Land moves, and we can measure
| that movement extremely precisely. If software was more
| competent, we would record positions in four dimensions: space
| and time, relative to a well defined coordinate system. And we
| could map a position at one time to a position at another time,
| with excellent accuracy.
|
| As far as I can tell, the only real limitations are a lack of
| standards and a lack of software support. I don't think any
| common CAD or GIS system has any particular support. Heck, QGIS
| will happily complain that WGS84 isn't good for high precision,
| and I can even tell whether this is a genuinely meaningful
| statement.
| Retric wrote:
| It's not just a software problem, you also need to know how
| the earth is being deformed which is far more difficult than
| you might think.
| arghwhat wrote:
| Not necessarily. Place a grid of receivers in fixed
| locations and observe their reported position. That grid is
| then the transform you need between the map when they were
| placed and the current state of the globe.
|
| A question would be how many you need, but these movements
| are on a large scale and receivers are dirt cheap.
| Retric wrote:
| A low resolution grid is cheap, but having enough censors
| for local accuracy is expensive because fault lines are
| so complicated:
|
| https://strangesounds.org/wp-
| content/uploads/2014/09/earthqu...
|
| What you really want is censers placed based on the
| underlying geology rather than a grid and then to combine
| that with a model of the geology.
| Retric wrote:
| *sensors
| chrismorgan wrote:
| This _is_ how things are done. You specify the datum,
| coordinates, and time. Geodetic datums are time-dependent
| transformation functions. Any software that is recording
| points at the particular time called "now" and not either
| recording the coordinates and time, or reprojecting them to a
| meaningful reference datum at its epoch (origin in time), is
| _bad_.
| amluto wrote:
| As far as I can tell, GIS software is _bad_ , then. I spent
| longer than seemed at all reasonable trying to research
| this with QGIS, and I got nowhere. ArcGIS (which I don't
| have) wasn't obviously better.
|
| Do you have an example of good software?
| chrismorgan wrote:
| Sorry, no. This was my dad's field, not mine, so I've
| just got a bunch of second-hand info and know that the
| software he worked on (two pieces, one for a company and
| one of his own) handled these sorts of things correctly.
| And I find it genuinely impossible to imagine that major
| GIS software would _not_ handle this, because it's so
| fundamental.
|
| Your GIS software will have you set a base CRS, and then,
| presuming it's not recording time on points, all
| coordinates will be relative to it at its epoch. That's
| all you need, now if you want to see what it's like _now_
| , you project it accordingly. Anything along the lines of
| recording new points based on actual measurements should
| _obviously_ either record time and position, or just
| position after performing the reverse transformation. But
| there you'd tend to be getting beyond the domain of what
| the bulky GIS software is doing, and into the domain of
| specific-purpose mobile apps and such.
| robocat wrote:
| > our super accurate GPS measurements are not 100% reliable
| over time
|
| The GPS measurements _are_ 100% reliable. Think of it like
| getting GPS co-ordinates while on a boat - it 's the boat that
| moves.
|
| A point of interest on land doesn't stay at the same
| latitude/longitude/altitude because land is a tectonic plate
| "boat" floating on the mantle.
|
| Close to the earthquake faultplane, land crumples and shears
| sideways and up/down. Plus secondary effects of the shaking:
| landslides, settlement, liquifaction.
|
| Finally: I think it helps to remember that earthquakes are
| fault _planes_. Talk of epicentres and depths and faultlines
| often misleads our intuitions. For one of the Christchurch
| earthquakes my parents were about a kilometre away from the
| faultline (where the faultplane met the surface) and many
| kilometres away from the epicentre (which is just a synthetic
| average point), but the faultplane actually was relatively
| close to them somewhere underneath their home.
|
| Also images of cracks in roads are often extremely misleading.
| They tend to be spectacular subsidence and are not the
| faultline. The actual faultline is usually not so photographic
| and less likely to have great photos early on. Media choses
| photos for their emotional appeal - not because they are a good
| approximation for the truth.
| oasisbob wrote:
| > The GPS measurements are 100% reliable. Think of it like
| getting GPS co-ordinates while on a boat - it's the boat that
| moves.
|
| I'm not sure this is a good metaphor. When doing high-
| accuracy GNSS (GPS) survey work, a static reference station
| is typically used to help correct errors from the GPS
| measurements themselves.
|
| If GPS was 100% consistent and reliable, differential
| correction wouldn't be a common and often-required technique:
|
| https://www.e-education.psu.edu/natureofgeoinfo/c5_p23.html
| helen___keller wrote:
| While you're correct that GNSS is not 100% accurate (like
| everything in the physical world, it comes with error
| bars), I think the point stands that the error is unrelated
| to the movement of continents.
|
| Ultimately GNSS is just measuring your position relative to
| some celestial objects using the time it takes for signals
| to propagate space (and some other info: their ephemerides,
| and a shared-ish clock). The fact that land exists, and
| where it exists, are not relevant
|
| Your error corrections might be thrown off when the base
| station moves, but that's not an issue of GNSS that's an
| issue of RTK
| philip1209 wrote:
| How property rights work when land shifts?
| intrasight wrote:
| Land could grow or shrink. I'd think split the difference.
| falcolas wrote:
| As I understand it (at least in the US), your land rights are
| based off of relative measurements from a static (to the land)
| point. They often look like medallions on the ground, anchored
| in place by fairly sizable stakes to ensure they don't easily
| move.
|
| The positions of those medallions... not as sure, but I imagine
| they are in turn positioned according to other static points.
|
| If the land cracks, well, I have no idea. That would be a legal
| battle no doubt.
|
| EDIT: These fixed points are called "common points" or "points
| of beginning (POB)", and there's usually one per neighborhood.
| There are also apparently buried iron rods (survey pins) that
| define property lines that can be found using a metal detector
| or such, but they are not foolproof.
| Symbiote wrote:
| The more common points are called trigonometrical points or
| triangulation stations.
|
| https://en.wikipedia.org/wiki/Triangulation_station
|
| https://en.wikipedia.org/wiki/Point_of_beginning
|
| (I'm surprised there's no link between these two articles.)
|
| https://en.wikipedia.org/wiki/Initial_point
| foobarian wrote:
| Reminds me of this marker story: "Belgian farmer accidentally
| moves French border" [1]
|
| [1] https://www.bbc.com/news/world-europe-56978344
| rwmj wrote:
| In Japan property boundaries are (often) marked with physical
| markers embedded into the ground:
| https://www.japantimes.co.jp/community/2015/01/02/how-tos/pr...
| https://japanpropertycentral.com/real-estate-faq/land-bounda...
| dexwiz wrote:
| Survey spikes are common worldwide. The issue is that they
| are not always where you think they would be. They are
| positioned relative to each other, were placed years ago, or
| moved by unscrupulous land owners. And until relatively
| recently it was all done by one person using an optical
| device looking at another person standing there with a
| colored stick.
|
| Surveyors are often called to resolve any discrepancies
| during disputes or sales.
| Kon-Peki wrote:
| In California, you file an action in court and they will redraw
| the property lines in a fair manner, allowing everyone affected
| to have a say in what counts as "fair".
|
| https://law.justia.com/codes/california/2009/ccp/751.50-751....
| shagie wrote:
| An example for Alaska.
|
| https://storymaps.arcgis.com/stories/662519e4406946faa6e655d...
|
| > Land within the Refuge that is tidally influenced up to the
| mean high-tide level, is managed by the Alaska Department of
| Fish and Game (ADF&G) for its unique recreational and wildlife
| values. As post-glacial rebound lifts the outer edges of the
| Refuge beyond the reach of the tides, the Refuge boundary
| shrinks. --->>> When glacial rebound lifts this new land above
| the high tide line, landowners adjacent to the Refuge can go
| through a legal process to claim this new land as a part of
| their property. <<<--- To ensure that these uplifted lands
| remain in their natural condition for habitat and recreation,
| the Southeast Alaska Land Trust (SEALT) sought partnerships
| with interested landowners through the Accreted Lands Project.
|
| And on the wiki page for post-glacial rebound, Finland has an
| example: https://en.wikipedia.org/wiki/Post-
| glacial_rebound#Legal_imp...
|
| > In areas where the rising of land is seen, it is necessary to
| define the exact limits of property. In Finland, the "new land"
| is legally the property of the owner of the water area, not any
| land owners on the shore. Therefore, if the owner of the land
| wishes to build a pier over the "new land", they need the
| permission of the owner of the (former) water area. The
| landowner of the shore may redeem the new land at market price.
| dang wrote:
| Related:
|
| _Magnitude 7.6 earthquake strikes Japan, tsunami warning issued
| for Ishikawa_ - https://news.ycombinator.com/item?id=38830281 -
| Jan 2024 (64 comments)
| aptitude_moo wrote:
| Obligatory XKCD: https://xkcd.com/2029/
| baron816 wrote:
| xkcd's what if had a video about the earthquake scale last month
| that was interesting
| https://youtu.be/e3uk7jU3RHo?si=RULnWlFTqUMqgWZe
| 1letterunixname wrote:
| 4' in Freedom Units. I'm wondering how well utilities and
| megastructures on the Noto Peninsula are able to cope with
| gradual and sudden shifts, even in Japan where earthquakes are
| assumed. It looks like Noto is being ripped and stretched NW from
| the mainland.
|
| ---
|
| Also, I re-read the Fukushima Daiichi report summaries yesterday.
| It's an almost universal human condition that plays out again and
| again: corporate risk management for large projects is done
| improperly, especially when there are constraints and cognitive
| dissonance imposed by the business culture, and it leads to a
| major failure.
|
| Points of the failure chain include:
|
| - Failure to account for known unknown risks such as the land
| subsidence combined with a large tsunami (based on the coastal
| geomorphology of the specific site).
|
| - Failure to protect critical EDGs from flooding, e.g., seawater
| intrusion. If trying to run a diesel motor near the ocean, it
| must be buttoned-up tighter than a Jeep with a snorkel including
| waterproofing sensors, wiring, and control systems. In general,
| sites should be chosen on very high ground with a large safety
| factor. If that's not possible, they should be placed on
| elevated, reinforced structures.
|
| - GE BWR-3/-4 (Mark I) core design is such that they can overheat
| and self-destruct, even if scrammed, because cooling is an
| absolute requirement at all times.
|
| - A lack of redundant, auxiliary, passive cooling ability, such
| as a gravity-fed reservoir that can be operated manually.
|
| - Regulators did insufficient due-diligence to prevent these
| risks.
|
| - "Made in Japan" failure of culture (this was part of the final
| report).
|
| - Using radionuclides that are inherently dangerous and produce
| forever waste rather than cheaper alternatives like solar with
| PES. Japan's solar just overtook nuclear, but still relies
| heavily on coal and gas. BWRs are inherently nastier than PWRs.
|
| Non-problems at FD:
|
| - Scramming worked properly, but the primary loops were still
| hot.
|
| Disclaimer: Worked in the nuclear industry where hostnames were
| Simpsons' character names.
| shagie wrote:
| Out There Learning - The Greatest Ever On-Land Fault Movement -
| https://youtu.be/LUsIIJwxPYU (length: 4m 25s)
|
| > Where is the world's greatest known on-land fault movement of
| any individual earthquake? It's at a place called Pigeon Bush
| near Wellington New Zealand. It is the surface trace of the
| Wairarapa Fault. In 1855 a magnitude 8.2 earthquake offset a
| small stream bed by about 18.5 metres which is the greatest
| single-event fault movement of any on-land fault in the globe!
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