GPS Is Going Places | Hacker News Reader

GPS Is Going Places

arstechnica.com

69 pointsTomte20 comments

GPS may be reliable for early warning of larger quakes. Both seismic waves and seismometers saturate at magnitudes above M7.5. That is to say its hard to tell a 7.5 from a 8 or 9 because appear similar size waves. It takes sophisticated computer analysis of a global set of seismographs to computer true quake size. This initial confusion happened in the disastrous 2011 Fukishima quake.

On the other hand working with GPS displacements gives an answer in less than a minute for larger quakes and more warning time.

https://eos.org/features/seismic-sensors-in-orbit-2

They mentioned probing snow.

How about if you could detect snow or ice on the road ahead of you by looking at gps reflections?

Seems like you could have a good idea what the reflections from a normal road surface look like and compare.

That sounds like a radar with extra steps.

Extra steps but no extra hardware sounds like a pretty good trade-off to me.

Common cellphone GPS being able to feel an earthquake would be incredible. Imagine Google Maps telling you to pull over because there was an earthquake, or redirecting you to safety.

Most phones today would already be able to feel an earthquake via the built-in accelerometer they have. Actually, there is a network of people sharing this information with each other already, called MyShake: https://myshake.berkeley.edu/

That app has great potential, but it's not really ready for prime time. Its rating in Google Play is 3.1 based on over 3,500 votes.

Today, they are apologizing for a problem wherein the app reported a 6.1 quake as being located somewhere in the United States, which is not very helpful.

Other reviewers have complained that the app is a power hog that drains a phone's battery pretty quickly.

https://play.google.com/store/apps/details?id=edu.berkeley.b...

> "Other reviewers have complained that the app is a power hog that drains a phone's battery pretty quickly."

I've seen it suggested before, but if this app or one like it only worked while the phone was plugged in, that would eliminate power consumption concerns and also provide cleaner data (a phone plugged in is usually sitting flat on a table, counter, etc, and is thus in a better position to collect seismic data than if it were in somebody's pocket.)

How do you differentiate an earthwuake from common behaviors while the phone is in a pocket such as running, jumping, walking etc.

Doesn't really seem that difficult. The patterns of picking up a phone, running with it and having it just lay on a vibrating surface are very different. It would be particularly easy to spot panic during a usual running routine.

More, I'd imagine you could look for a signal common to many devices. Unless you are picking up all phones in your household with the same signal, any signal common to them all is likely more global. Could detect if folks are in the same car?

> Doesn't really seem that difficult

Companies lose billions on projects every year because someone uttered these exact same words.

You compare it with other phones in the nearby area.

Right. At any time, most phones will be lying on something like a table. If they all sense something, it's a big external event.

So you compare each and every devices state every X seconds to determine if somethings that statistically never happens is happening?

I can't be the only thinking this is nonsense. Just install a bunch of actual earthquake detectors and make them send notifications via already existing alert systems.

I'm just saying it can be done. Not that it should be the new gold standard.

A less chatty implementation would be if each phone only contacted the server when it sensed a possible quake. If it gets a few correlated hits, it can even send out a "hey did everyone feel that?" question.

Why not use accelerometer for that

I prefer the Japanese system where they invested in a network of seismometers and blast out a notification, so your phone alerts you of the earthquake before it reaches you

All these "things" GPS can do involve the satellite signals being received by very specialized equipment, not cell phones which arguably the title implies.

>not cell phones which arguably the title implies.

Let's examine the title:

>GPS is going places

Nothing about cellphones.

Maybe it's in the byline?

>Here are five things you didn’t know the navigation system could do.

Nothing there either.

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