USNSN Noise Analysis

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Networks Contributed to NEIC in Real-time
Contributors via VDL
MEDNET GEOFON KNET IMS CDSN GTSN GSN
SLU AEIC BKY SNL Weston BILIKIN LLNL
Contributors via EW
ATWC PTWC AVO NMT USBR SLU Menlo
CERI Butte TriNet UUSS UNR LDEO MIT
170 Broadbands
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NEIC Real-time Data System
RSN
TWC
ISN
USNSN vsat
RSN
Earthworm
VMS Cluster
NEIC Products
Research
Waveserver
IRIS DMC
QA/QC
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USNSN Noise Analysis
Motivation

• Station noise characteristics
• Diurnal/seasonal variations
• Geography/location
• Installation type
• Station maintenance issues
• transients
• ANSS backbone station design
• ANSS backbone siting criteria
• Network detection thresholds
• ANSS , USNSN, GSN
• Microseism source research
• Cultural noise source modeling

Hailey, ID 08/2001-05/2002
2370 individual PSDs, binned in 1/8 octave
intervals, are used to construct a Seismic Noise
Probability Density Function for HLID BHZ, shown
to the right.
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USNSN Noise Monitoring for QA/QC
Raw waveforms continuously extracted from
waveserver In 1 hour segments, overlapping by
50. PSD pre-processing trend and mean
removal 10 cos taper applied No screening for
earthquakes, or transients and instrumental
glitches such as data gaps, clipping, spikes,
mass re-centers or calibration pulses
PSD calculated for each 1 hour segment With ASL
algorithm for direct comparison to NLNM. PSD is
smoothed by averaging powers over full octaves in
1/8 octave intervals. Center points of averages
shown.
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Power Frequency Distribution
After 1 year, thousands of PSDs
computed. Histograms generated for each period
bin. powers in 1dB bins. Next step Histograms
converted to PDFs. Normalize each power bin by
total Number of observations.
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Artifacts in the Noise Field
Numerous artifacts are observed and
identifiable. Strong signals are generated from
instrumentation and telemetry issues such as
calibration pulses, automatic mass re-centering
and dropped packets. We also observe
significant power around 0.1 sec (10Hz) due to
this stations proximity to a road.
Cars
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Seismic Noise PDFs
Continental Interior Mine Site
Continental Interior Borehole Site
Idaho Springs, CO
Bozeman, MT
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Seismic Noise PDFs
Eastern US Binghamton, NY
Island Site Big Island Hawaii
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USNSN Noise Characteristics
90th percentile noise model mapped for each USNSN
station.
Seismic noise will vary as a function of
geography and frequency.
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6am local time
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USNSN Noise Analysis
Next Step
Hailey, ID 08/2001-05/2002

• Web station book
• Real-time noise PDF
• Noise history
• Diurnal/seasonal variations
• Station/Network SOH
• transients
• IRIS software framework
• Community tool
• Earthworm module
• RSN