THE MVO SEISMIC NETWORK PRESENTER NAME CO-AUTHORS AFFILIATIONS

THE MVO SEISMIC NETWORK PRESENTER NAME, CO-AUTHORS AFFILIATIONS

Outline The MVO seismic network Data acquisition and processing at MVO Quality of data Seismic monitoring of SHV • Stations design • Digital telemetry • SCREAM! +Earthworm • SEISAN • Automatic QC procedures • Data QC at MVO • A variety of peculiar seismic signals • Earthquake activity during 13 years of eruption

The MVO seismic network Sites locationandtelemetry 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

The MVO seismic network Stationcomposition - Guralp CMG-40 T seismometer – 3 component, T= 30 s - Guralp CMG-DM 24 digitizer – GPS, 100 Hz sampling - Freewave FGR-115 spread-spectrum radio – ~900 MHz - Solar panel, batteries, etc

The MVO seismic network Station design - Custom-built 1. 5 x 1. 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.

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 Güralp instruments including full mass control, calibration, digitizer output configuration and triggering - Advanced networking capabilities

Data acquisition and processing Earthworm MVO installation of Earthworm includes most of the modules that can be downloaded from the web - Original modules modified and recompiled at MVO: , scream 2 ew, ew 2 rsam, waveman 2 disk wave_Server. V, - BGS modules: archman - MVO in-house modules: dirwatch, export_seisan, newheli, newsgram, rsam 2 alarm, scream_alarm, rsam 2 file, sound_alarm, swarm_alarm, test_alarm, weather 2 file.

Data acquisition and processing SEISAN - > earthquake analysis system developed by Jens Havskov and Lars Ottemöller (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

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Data quality control (QC) Seismic data quality control is required for early detection of: Sensors malfunctions Digitizer & recorder malfunctions Vault problems: tilting, settling, etc Cable & connection problems Telemetry issues Timing problems

Data quality control automated quality control 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 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

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

Volcano-seismic signals VT/LP/Hybrids/Rockfalls (Data courtesy MVO and UWI/IPGP) VT (Brittle-failure) Long-period (Volumetric sources) Hybrid (Shear failure of magma ? Regular VT + attenuation/patheffects ? ) Rockfall

Volcano-seismic signals surface signals/rockfalls and pyroclastic flows (Photo, courtesy MVO and UWI/IPGP)

Volcano-seismic signals Examples (Data and photo, courtesy MVO and UWI/IPGP) Spectrogram display tremor associated with venting (SHV, September 11 th 2006)

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

Volcano-seismic signals 12 years of eruption seismicity at SHV (Data courtesy MVO and UWI/IPGP)

Thank you