1. The EarthScope USArray Transportable Array: Results from Large-scale Network Operations
Bob Woodward, Bob Busby, Katrin Hafner, and David Simpson
Incorporated Research Institutions for Seismology
(IRIS)
CTBT S&T 2011 Conference
June 8-10, 2011
Vienna, Austria

2. Outline Describe the Transportable Array (TA)
Performance of the Transportable Array
Operational Strategies

3. The Transportable Array
Large scale broadband stations
Transient stations – network configuration changes daily
Large investment – high expectations
1,680 sites
19 sta / month
4.5 Gb / day
$10M / year
Red = current array location
Grey = stations already removed

4. Array & Station Design 400 broadband seismic stations Goals
~70 km spacing
~2000 x 1000 km “footprint”
~2 year deployments at each site
10 years and 1623 sites to roll across the country
Goals
High-quality broadband data
Maximize data return (>85%)
Data in near real time
40 and 1 sps continuous

5. TA Performance Network availability typically exceeds 98%
Station noise highly uniform and quite low for temporary installations

6. Uniformity of Stations
Standard vault design
Modular communications
Vault interface enclosure
Encloses everything but the DAS and seismometer
Low-power autonomous operation
A typical operating TA Station
535A Dale TX
Station deployment treated as a high-precision manufacturing operation

7. Multipart Approach to QC
Array Network Facility (network hub)
Builds tools and automated processes to gather status, inventory, and operational diagnostics for real-time monitoring
Performs picking and associations that occasionally detect waveform issues
Data Management Center (archive and distribution)
Analysts review all long-period data and catalog subtle changes in character
Run automated tools to parameterize certain data qualities
All reports go to TA management for integration and action

8. State-of-Health Review
Real-time monitoring of SoH
Detect problems
Initiate corrective actions
Station QC & SoH on the web
SoH channel displays
Both near-real-time and summary
Metrics for arbitrary time intervals
Mass position - life of station
PDF noise analysis by station-channel
Temperature and voltage - life of station
From ANF station status web pages
From DMC QUACK tool

9. Web-based Monitoring http://anf.ucsd.edu/tools/webdlmon
Identify changes and how they accumulate over time
E.g., - in last 24 hours: number of reboots, number of IP changes, number of link cycles
Alerts: Some status changes result in an alert to distribute more information immediately about the change: Pump active signal, Q330 reboot
Monitoring system renders data into actionable format
Information then feeds weekly management prioritization for all service activities

10. Orientation Direct measurement of orientation of all stations
Using fiber-optic gyroscope
Measures orientation to < 0.2o
When station is installed
When station is removed
Direct measurements validate empirical estimates
Empirical orientation estimates from surface and mantle wave polarization techniques
As of % of the TA stations have polarization anomalies within +-3 degrees
In 2008, this number was 79.9%
TA station orientation, relative to north, from empirical analysis
Results from Ekström and Busby, SRL, 2008

11. Calibration
Automated process for command, capture, and analysis of cal signals
Analysis of calibration signals to verify amplitude and phase response
Applied to all TA stations at beginning and end of deployment
System wide calibration in 2009

12. Station Evolution
Adding pressure transducers to create a 400 station atmospheric acoustic (infrasound) network
Span frequency band from DC to 20 Hz
TA Station 345A, MS

13. EarthScope is funded by the National Science Foundation.
Summary
400 station network operating at >98% availability
Uniform, autonomous, low-power stations
Multipart approach to QC
Real time SoH channels
Interactive reviews
Automatic reviews, short-term and long-term behavior
QC feeds actionable information to TA Management
Attention to calibration, orientation, and trends in data
Careful evolution of stations
Info on the Web
EarthScope
USArray
National Science Foundation
EarthScope is funded by the National Science Foundation.
EarthScope is being constructed, operated, and maintained as a collaborative effort with UNAVCO, and IRIS, with contributions from the US Geological Survey, NASA and several other national and international organizations.