community seismic network daniel obenshain along with k. mani chandy, robert clayton, andreas...

Community Seismic Community Seismic NetworkNetwork

Daniel ObenshainDaniel Obenshain

along withalong with

K. Mani Chandy, Robert Clayton, Andreas Krause, K. Mani Chandy, Robert Clayton, Andreas Krause, Michael Olson, Matthew Faulkner, Leif Strand, Michael Olson, Matthew Faulkner, Leif Strand, Rishi Chandy, Daniel Rosenberg, Annie Tang, Rishi Chandy, Daniel Rosenberg, Annie Tang,

and othersand others

California Institute of TechnologyCalifornia Institute of Technology

XKCDXKCD

Image by Randall Munroe of xkcd.com, Creative Commons Attribution-Noncommercial 2.5 License

Internet and EarthquakesInternet and Earthquakes

In the comic:In the comic:– The tweets travel faster than the The tweets travel faster than the

earthquakeearthquake– Other users get quake information Other users get quake information

before it hitsbefore it hits– They are too slow to do anything about They are too slow to do anything about

it.it.

BackgroundBackground

Earthquakes are dangerous threatsEarthquakes are dangerous threats– USGS estimates 2000 deaths and $200 billion USGS estimates 2000 deaths and $200 billion

damages from 7.8 magnitude quakedamages from 7.8 magnitude quake



damages from 7.8 magnitude quakedamages from 7.8 magnitude quake Early warning could minimize sufferingEarly warning could minimize suffering

– Activate safeguards in critical operationsActivate safeguards in critical operations




– Activate safeguards in critical operationsActivate safeguards in critical operations Providing early warning is an interesting Providing early warning is an interesting

problemproblem– Bayesian decision theory, geology, distributed Bayesian decision theory, geology, distributed

computingcomputing




– Activate safeguards in critical operationsActivate safeguards in critical operations Providing early warning is an interesting Providing early warning is an interesting

problemproblem– Bayesian decision theory, geology, distributed Bayesian decision theory, geology, distributed

computingcomputing Current seismic network is too sparseCurrent seismic network is too sparse

– Can’t provide enough early warningCan’t provide enough early warning

Sensor Network is too Sensor Network is too SparseSparse

A sensor network of one hundred sensors.

A sensor network of one thousand sensors.

SCSN (Southern California Seismic Network) has ~350 sensors right now.

Pause for ExamplePause for Example

Sensor Network is too Sensor Network is too SparseSparse

Ten thousand sensors! Both a 3 second wave and a 1 second wave.

Early Warning Can HelpEarly Warning Can Help

Slow trains


Slow trains

Stop elevators


Slow trains

Stop elevators

Open fire station doors


The information The information can also help the can also help the electrical grid.electrical grid.

Southern California Edison Territory



The grid can be The grid can be shut down and shut down and made safe prior to made safe prior to severe shaking.severe shaking.




The grid can be The grid can be shut down and shut down and made safe prior to made safe prior to severe shaking.severe shaking.

Power back in a Power back in a day, not weeks day, not weeks after earthquake.after earthquake.


BenefitsBenefits

Provide Early WarningProvide Early Warning Easy deployment in areas without Easy deployment in areas without

existing seismic networksexisting seismic networks– Peru and IndonesiaPeru and Indonesia

Cell phones are prevalentCell phones are prevalent

Identify hard-hit areas quicklyIdentify hard-hit areas quickly– Direct first respondersDirect first responders

That’s why we’re That’s why we’re doing it.doing it.

What about how What about how we’re doing it?we’re doing it?

Expand the NetworkExpand the Network

We want to add more data.We want to add more data.


We want to add more data.We want to add more data. Why not get data from as many Why not get data from as many

sources as possible?sources as possible?



sources as possible?sources as possible? Add in acceleration devices of Add in acceleration devices of

different types, cell phones, laptops, different types, cell phones, laptops, etc.etc.



sources as possible?sources as possible? Add in acceleration devices of Add in acceleration devices of

different types, cell phones, laptops, different types, cell phones, laptops, etc.etc.

The User installs some client software The User installs some client software and his or her acceleration data and his or her acceleration data becomes part of the network.becomes part of the network.

The ClientThe Client

Registration

Handler

SensorHandler

ServerRegistration

Handler

Error, NoUpdate, orHandlers

Calculation

Handler

Alert Handler

Controller

Registration handler invoked on first run

Returns Proceed, Error, or New Handlers

Handlers and Queues managed

Core

pro

cessin

g

ServerAlert

Listener

Example Client – Cell PhoneExample Client – Cell Phone

Measures 3-D accelerationMeasures 3-D acceleration Program runs in Program runs in

backgroundbackground Especially good while Especially good while

chargingcharging

Example Client – Cell PhoneExample Client – Cell Phone

Martin Lukac (of UCLA) recorded a minor seismic Martin Lukac (of UCLA) recorded a minor seismic event on a Nokia phone, with different software.event on a Nokia phone, with different software.

Picking AlgorithmPicking Algorithm

How often should the client send How often should the client send data to the server?data to the server?



Only when significant shaking is Only when significant shaking is occurring.occurring.




How does the client know?How does the client know?




How does the client know?How does the client know? It performs a simple calculation on It performs a simple calculation on

the incoming data stream.the incoming data stream.




How does the client know?How does the client know? It performs a simple calculation on It performs a simple calculation on

the incoming data stream.the incoming data stream. We call this the “Picking Algorithm.”We call this the “Picking Algorithm.”


STA/LTA > trigger


STA – Short Term Average : the STA – Short Term Average : the average acceleration over the past average acceleration over the past several data pointsseveral data points

STA/LTA > trigger



LTA – Long Term Average : the LTA – Long Term Average : the average acceleration over more data average acceleration over more data pointspoints

STA/LTA > trigger



LTA – Long Term Average : the LTA – Long Term Average : the average acceleration over more data average acceleration over more data pointspoints

trigger – a thresholdtrigger – a threshold

STA/LTA > trigger


Accelerometer

Long Term Average

Short Term Average


Accelerometer

New DataLong Term Average

Short Term Average


Accelerometer

Short Term Average

Long Term Average


If STA/LTA > trigger is true, then we If STA/LTA > trigger is true, then we have “picked.”have “picked.”



The algorithm then waits a little bit The algorithm then waits a little bit before sending a message to the before sending a message to the server.server.



The algorithm then waits a little bit The algorithm then waits a little bit before sending a message to the before sending a message to the server.server.

This is to make sure it sends data This is to make sure it sends data from the peak of the wave.from the peak of the wave.


Pause for this length of time beforesending a message to the server.

1 2 3

1. Detected significant shaking2. Maximum shaking3. Sent message to server


After sending a message to the After sending a message to the server, the client will wait a while server, the client will wait a while before picking again.before picking again.


After sending a message to the After sending a message to the server, the client will wait a while server, the client will wait a while before picking again.before picking again.

This is to stop the client from picking This is to stop the client from picking multiple times for the same shaking.multiple times for the same shaking.


Delay for this length of timebefore picking again.

1

1. Last message sent to server2. The coda of the earthquake,

where we don’t want to pick

2


Five tunable parameters.Five tunable parameters.


Five tunable parameters.Five tunable parameters.– Length of STALength of STA


Five tunable parameters.Five tunable parameters.– Length of STALength of STA– Length of LTALength of LTA


Five tunable parameters.Five tunable parameters.– Length of STALength of STA– Length of LTALength of LTA– Value of triggerValue of trigger


Five tunable parameters.Five tunable parameters.– Length of STALength of STA– Length of LTALength of LTA– Value of triggerValue of trigger– How long to wait after picking before How long to wait after picking before

sending a message to the serversending a message to the server



sending a message to the serversending a message to the server– How long to wait between messagesHow long to wait between messages



sending a message to the serversending a message to the server– How long to wait between messagesHow long to wait between messages

They can all be tuned by the server, They can all be tuned by the server, on a client-by-client basis.on a client-by-client basis.

GUIGUI

Acceleration data is displayed in real Acceleration data is displayed in real time on the user’s screen.time on the user’s screen.

GUIGUI


Promotes use of the software.Promotes use of the software.

GUIGUI


Promotes use of the software.Promotes use of the software. Can be used in science classrooms to Can be used in science classrooms to

explain project.explain project.

GUIGUI


Promotes use of the software.Promotes use of the software. Can be used in science classrooms to Can be used in science classrooms to

explain project.explain project. Each message to the server marked Each message to the server marked

by a red line.by a red line.

GUIGUI

3 Axes3 Axes

GUIGUI

3 Axes3 Axes Data streams from Data streams from

the rightthe right

GUIGUI

3 Axes3 Axes Data streams from Data streams from

the rightthe right The red line The red line

represents a represents a message to the message to the serverserver

Client-server messagesClient-server messages

RegistrationRegistration PicksPicks HeartbeatHeartbeat


RegistrationRegistration– Location (or an approximation)Location (or an approximation)– Given a client idGiven a client id

PicksPicks HeartbeatHeartbeat


RegistrationRegistration PicksPicks

– Short UDP messageShort UDP message– Location, time, and acceleration Location, time, and acceleration

experiencedexperienced– Can be a playback message!Can be a playback message!

HeartbeatHeartbeat


RegistrationRegistration PicksPicks HeartbeatHeartbeat

– Check in with serverCheck in with server– Get any updates, playback infoGet any updates, playback info– For security, server will never push For security, server will never push

updates. Client must call in to get updates. Client must call in to get updates.updates.


RegistrationRegistration PicksPicks HeartbeatHeartbeat All are in XML format.All are in XML format.

– Human readableHuman readable– Easily extendedEasily extended– Can easily interface with other, similar Can easily interface with other, similar

projectsprojects

Sensor ValidationSensor Validation

Tested our sensor with artificial Tested our sensor with artificial event.event.



Compared our sensor to the SCSN Compared our sensor to the SCSN (Southern California Seismic (Southern California Seismic Network) sensor in the basement of Network) sensor in the basement of Millikan Library.Millikan Library.



Compared our sensor to the SCSN Compared our sensor to the SCSN (Southern California Seismic (Southern California Seismic Network) sensor in the basement of Network) sensor in the basement of Millikan Library.Millikan Library.

Caused seismic activity with a Caused seismic activity with a sledgehammer.sledgehammer.


We have since switched to better noise We have since switched to better noise filtering and a better sensorfiltering and a better sensor

Still, the correlation is visibleStill, the correlation is visible

ServerServer

Four main tasksFour main tasks– Handle new user registrationHandle new user registration

ServerServer

Four main tasksFour main tasks– Handle new user registrationHandle new user registration– Listen for pick messagesListen for pick messages

ServerServer

Four main tasksFour main tasks– Handle new user registrationHandle new user registration– Listen for pick messagesListen for pick messages– Handle heartbeat messagesHandle heartbeat messages

ServerServer

Four main tasksFour main tasks– Handle new user registrationHandle new user registration– Listen for pick messagesListen for pick messages– Handle heartbeat messagesHandle heartbeat messages– Analyze dataAnalyze data

ServerServer

Registration Handler

Pick Handler

Heartbeat Handler

Database Associator

UDP vs TCPUDP vs TCP

We send messages using two different We send messages using two different protocols.protocols.

TCP (Transmission Control Protocol)TCP (Transmission Control Protocol)– Handshake delayHandshake delay– Error correctionError correction

UDP vs TCPUDP vs TCP

We send messages using two different We send messages using two different protocols.protocols.

TCP (Transmission Control Protocol)TCP (Transmission Control Protocol)– Handshake delayHandshake delay– Error correctionError correction

UDP (User Datagram Protocol)UDP (User Datagram Protocol)– FastFast– UnreliableUnreliable

Pick Message HandlerPick Message Handler

Pick messages are sent using UDP Pick messages are sent using UDP packets.packets.

Reasons:Reasons:– Unsure of condition of networkUnsure of condition of network– Speed is importantSpeed is important

Indiana Jones EffectIndiana Jones Effect

From Indiana Jones and the Raiders of the Lost Ark.


Listen for incoming picksListen for incoming picks


Listen for incoming picksListen for incoming picks– Parse messageParse message


Listen for incoming picksListen for incoming picks– Parse messageParse message– Check for playback flagCheck for playback flag

If the flag is not present, the pick is stored in If the flag is not present, the pick is stored in the database.the database.

If the message is flagged as playback, it is If the message is flagged as playback, it is written to a separate table in the database.written to a separate table in the database.

Server OperationServer Operation

Registration

Listener

Alert Listener

Calculation

Handler

WarningHandler

Controller

Core

pro

cessin

g

Equipment, devices,notification systems

Heartbeat

Listener

ClientsClientsClientsClientsClientsClientsClientsClientsClients

Server-side AnalysisServer-side Analysis

Bayesian decision-makingBayesian decision-making

Server-side AnalysisServer-side Analysis

Bayesian decision-makingBayesian decision-making

Once posterior is sufficient, we send Once posterior is sufficient, we send Early WarningEarly Warning

Tested on Fake DataTested on Fake Data

Priors from Priors from Gutenberg-Richter Gutenberg-Richter law (mag vs. num)law (mag vs. num)

Fake data stream Fake data stream with errors in itwith errors in it

Located epicenter Located epicenter to within 25 kmto within 25 km

Located epicenter Located epicenter in 10 secondsin 10 seconds

Display dataDisplay data

Heat mapHeat map Hotter colors = higher magnitude Hotter colors = higher magnitude

pickspicks


http://map.communityseismicnetwork.org/

Google App EngineGoogle App Engine

Server Server implemented on implemented on Google App EngineGoogle App Engine

Our data is sent to Our data is sent to and stored thereand stored there

Robust, scalableRobust, scalable

Machine LearningMachine Learning

Feedback loopFeedback loop Five parameters (or more!) per clientFive parameters (or more!) per client If a client picks more often than If a client picks more often than

normal, tune it downnormal, tune it down If a client picks less often than If a client picks less often than

normal, tune it upnormal, tune it up

Machine LearningMachine Learning

A client next to A client next to constructionconstruction

Not useful for small Not useful for small seismic eventsseismic events

Still useful for big Still useful for big ones!ones!

Set the threshold Set the threshold higher.higher.

Thank YouThank You

Q&A SessionQ&A Session

community seismic network daniel obenshain along with k. mani chandy, robert clayton, andreas...

Documents

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helpslow trainsearly

station doorsearly warning

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electrical grid

helpthe information

examplesensor network