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Slide 2 Outline Stations design Digital telemetry The MVO seismic network SCREAM! +Earthworm SEISAN Data acquisition and processing at MVO Automatic QC procedures Data QC at MVO Quality of data A variety of peculiar seismic signals Earthquake activity during 13 years of eruption Seismic monitoring of SHV Slide 3 The MVO seismic network Sites location and telemetry 11 DIGITALLY TELEMETERED SITES - Spread spectrum Freewave radio modems (900 MHz) at each site - 2 repeater sites equipped with serial-to-IP converters and microwave TCP/IP routers Slide 4 The MVO seismic network Station composition - Guralp CMG-40T seismometer 3 component, T= 30 s - Guralp CMG-DM24 digitizer GPS, 100 Hz sampling - Freewave FGR-115 spread-spectrum radio ~900 MHz - Solar panel, batteries, etc Slide 5 The MVO seismic network Station design - Custom-built 1.5x1.5x1.5 m fiberglass box almost entirely buried in the ground and cemented into place. - Removable lid allows easy access to the instrument. - Seismometer installed on a concrete plinth and tightly wrapped in a thick layer of styrofoam (provides thermal insulation and avoids thermal convection around the instrument) - The digitizer is positioned on top of the seismometer housing. Slide 6 Data acquisition and processing SCREAM ! Scream! software -> Seismometer Configuration, Real time Acquisition and Monitoring - Receive data over TCP/IP link (can handle serial, dial-up links, UDP/IP or any combination of these) - Low-overhead GCF format for data transfer - Display any number of incoming streams with real-time spectrogram calculation - User-friendly interface to Gralp instruments including full mass control, calibration, digitizer output configuration and triggering - Advanced networking capabilities Slide 7 MVO installation of Earthworm includes most of the modules that can be downloaded from the web - Original modules modified and recompiled at MVO:, scream2ew, ew2rsam, waveman2disk wave_ServerV, - BGS modules: archman - MVO in-house modules: dirwatch, export_seisan, newheli, newsgram, rsam2alarm, scream_alarm, rsam2file, sound_alarm, swarm_alarm, test_alarm, weather2file. Data acquisition and processing Earthworm Slide 8 Data acquisition and processing SEISAN SEISAN - > earthquake analysis system developed by Jens Havskov and Lars Ottemller (Freeware - cross-platform portability - ) - Easy to manage data from one network with SEISAN - Comprehensive suite of tools to extract database info in fully automated and semi-automated way are part of the SEISAN installation - Programs for routine observatory seismology practice (earthquake locations, focal mechanisms, event counts and statistics, seismic bulletins, etc.) - Programs for advanced research tasks (cross-correlation waveform analysis, waveform modeling/moment tensor inversion, coda Q, and many others) At MVO a few other scripts have been developed to interact with SEISAN including: - Plotting tools - Scripts to read phase information and prepare input for other seismic programs Slide 9 9 Slide 10 Data quality control (QC) Sensors malfunctions Digitizer & recorder malfunctions Vault problems: tilting, settling, etc Cable & connection problems Telemetry issues Timing problems Seismic data quality control is required for early detection of: Slide 11 The challenge is to minimize manual analyst work by automating as many measurements and monitoring systems as possible - Signal RMS -> Long-term (e.g.monthly) can help identifying seasonal effects, Short- term helps identifying sensors/digitizers malfunctioning - Signal mean -> Good diagnostic tool for seismometer mass calibration - Noise PSD/PDF -> Characterize background noise levels - Data Flow -> Mb/day, no channels/day may indicate telemetry dropouts Data quality control automated quality control Slide 12 Data quality control manual quality control Manual quality control procedures at MVO include : - Visual review of raw data for triggered events and of raw continuous data - Polarity - GPS time-stamping - Review of measurements and alerts from automated system Slide 13 Volcano-seismic signals classification -High-frequency (HF) or Volcano-tectonic (VT) -Long-period (LP) -Hybrids or mixed-frequency (Sometimes LP and Hybrids called collectively Low-frequency,LF) -Volcanic tremor -Surface signals Slide 14 Volcano-seismic signals VT/LP/Hybrids/Rockfalls VT (Brittle-failure) Long-period (Volumetric sources) Hybrid (Shear failure of magma ? Regular VT + attenuation/patheffects ?) Rockfall (Data courtesy MVO and UWI/IPGP) Slide 15 Volcano-seismic signals surface signals/rockfalls and pyroclastic flows (Photo, courtesy MVO and UWI/IPGP) Slide 16 Volcano-seismic signals Examples Spectrogram display tremor associated with venting (SHV, September 11 th 2006) (Data and photo, courtesy MVO and UWI/IPGP) Slide 17 Volcano-seismic signals Eruption signals (Data courtesy MVO and UWI/IPGP) Helicorder and RSAM displays from dome collapse on May 20 th, 2006 at SHV Slide 18 Volcano-seismic signals 12 years of eruption seismicity at SHV (Data courtesy MVO and UWI/IPGP) Slide 19 Thank you