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Seismic Instrumentation

Seismic Instrumentation. Caribbean training course in Seismology and Tsunami Warnings 25-30 June, 2007 University of the west Indies St. Augustine Trinidad and Tobago. Seismic Monitoring.

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Seismic Instrumentation

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  1. Seismic Instrumentation Caribbean training course in Seismology and Tsunami Warnings 25-30 June, 2007 University of the west Indies St. Augustine Trinidad and Tobago

  2. Seismic Monitoring • Seismology is a fundamental tool for investigating the kinematics and dynamics of geological processes at all scales • It involves the propagation of seismic waves through the Earth • Provides detail measurements made at the surface that suggest or imply what is happening at depth

  3. Wave Propagation and Seismograms

  4. Sources of Seismic Waves • earthquakes, • volcanic eruptions, • weather and ocean waves, • meteorite impacts, • cultural activities, • underground nuclear explosions.

  5. Instrumental Characteristics Different instruments can access different zones within the overall strain field of the plate boundary. Source: http://www.earthscope.org

  6. Simple Seismograph The seismometer together with the unit recording the signal is called a seismograph. The seismometer senses the ground vibration and converts this to a signal that can be recorded. Seismographs can detect, amplify, and record ground vibrations too small to be perceived by human beings. Modern seismographs can measure movements smaller than one nm.

  7. Definitions Seismometer: • A seismometer is a sensor used to detect weak ground motion. The most common type of seismometer is made from a pendulum or a mass mounted on a spring. While seismometer is often used synonymously with "seismograph“, strictly speak, it is usually the component of a seismograph (definition follows) that senses the ground motion. Seismograph: • A sensitive instrument that can detect, amplify, and record ground vibrations too small to be perceived by human beings. Seismographs are primarily used to record the motion of the ground produced by earthquakes. Seismogram: • A graph showing ground motion versus time. On a seismogram, the X-axis denotes time while the Y-axis denotes ground displacement. Accelerograph • A ground motion recorder whose output is proportional to ground acceleration • Typically used to record very strong ground motion useful in engineering design; seismographs commonly record off scale in these circumstances.

  8. Contemporary Seismic Instruments Guralp CMG-T Accelerometer Streckeisen STS-2 Broadband Seismometer Guralp CMG-3T Digital BB Seismometer Teledyne GS-13 SP Seismometer

  9. Installation of a BB/SM Seismic Station in St. Vincent Location – Volcano Observatory Clear view for VSAT Excavate hole for power cable and sensor vault

  10. Installation of a BB/SM Seismic Station in St. Vincent Vault Construction and Seismometer Installation

  11. EQUIVALENT EARTH PEAK ACCELERATION ( 20 LOG M/SEC 2 ) PERIOD (SECONDS) Spectrum of Seismic Instrumentation

  12. Bandwidth and Dynamic Range

  13. Weighing In Earthquakes Broadband sensors are good for studying: Large – Great events at teleseismic distances Regional events up to M6.5 Local events up to M5.3 Accelerometers are good for studying: Events of felt intensity including local events in excess of M8.0

  14. Applications for Seismic Instruments • As a tool to monitor and study volcanoes • Early warning systems – tsunami, volcanic eruptions • To investigate the dynamic response of structures • To study and monitor regional seismicity in an effort to access the earthquake hazard potential - provisions for building code - design parameters for critical facilities - to inform land use policies and mitigation plans - to inform emergency preparedness plans

  15. Evolution of Seismic networks • Autonomous Seismographic Stations • Poor timing • Data processing cumbersome • Analog Micro-earthquake Networks • Improved Timing • Limited Dynamic Range and Data Processing • Hybrid Micro-earthquake Networks • Limited dynamic range • Improved data processing • Digital Seismograph Networks • Vastly improved dynamic • Very good accuracy • Versatile processing but size usually limited • Virtual Seismograph Networks • Many of the good attributes listed above

  16. Wilmore photographic seismograph Analog Seismic Stations

  17. Components of a Micro-earthquake Network

  18. Remote Field Station Remote Field Station Remote Field Station Remote Field Station Analog Signal Reception Time Sync Analog/Digital Converter Central Recording/Processing Site Hybrid Network Analog Data Transmission Digital Recording and Data Processing System

  19. Seismic Research Unit: Network of Seismic Stations Dominica Sub-Nets St. Kitts and Nevis Sub-Net Leeward Is Sub-Net N. A. Stations St. Vincent Sub-Net Data Repository FTP SERVER Barbados Station Grenada Sub-Net Trinidad Sub-Networks St Lucia Sub-Net

  20. Download Buffer Files Extract and Process Seismograms Determine Preliminary Earthquake Parameters Disseminate Information to Disaster Preparedness Coordinators & Media Data Processing and Information Dissemination ~2-3 Monitors, ~ 10 Minutes ~ 10 Minutes ~ 5 Minutes ~ 5 Minutes End-to-End Time, ~ 25 - 30 Minutes

  21. Time Sync Time Sync Time Sync Time Sync Digital Field Station Digital Field Station Digital Field Station Digital Field Station Digital Recording and Data Processing System Digital Network Digital Data Transmission

  22. Digital Station Clock to Timestamp Data Digital Comms On Sensor DAS to convert electric current to numbers for a computer to process Analysis and Storage PC to configure System Power Supply may be solar or Mains

  23. Central American Broad Band Seismic Network, Yucatan Puerto Rico Mexico IMS Operating, on line Not functioning Venezuela IRIS Under Construction Colombia Cocos Isl. Galapagos/Ecuador

  24. Caribbean Seismic Networks Many countries have realized the importance of seismic monitoring of their territories. There are over 30 seismological institutions and several hundred channels of data in the Caribbean

  25. Seismic Networks Covering the Caribbean Region • VENEZUELA • Laboratorio de Geofísica, Universidad de los Andes (UAV) • Fundación Venezolana de Investigaciones Sismológicas -FUNVISIS • Centro de Sismología, Universidad de Oriente - (UDO) • EASTERN CARIBBEAN • Seismic Research Unit (SRU), UWI • IPG Observatoire Geophysique (IPG) • Dominica Public Seismic Network – DPSN • Montserrat Volcano Observatory (MVO) • NORTHERN CARIBBEAN • Red Sísmica de Puerto Rico (PRSN) • Instituto Sismologico Universitario (ISU) • Red Sísmica Dominicana • Jamaica Seismograph Network, UWI, Mona • Centro Nacional de Investigaciones Sismológicas-CENAIS • Cayman Is. Network

  26. Seismic Networks Covering the Caribbean Region COLUMBIA • CADAFE, Desarrollo Uribante Caparo-DESURCA (DESU) • Observatorio Sismológico del SurOccidente (OSSO) • Red Sísmica Nacional De Colombia - INGEOMINAS • Universidad del Valle (UVC) CENTRAL AMERICA • Instituto de Geociencias, Universidad de Panamá (UPA) • Observatori Vulcanológico y Sismológico de Costa Rica - OVSICORI-UNA • Red Sismológica Nacional, Univ. de Costa Rica (UCR) • Unidad de Amenazas y Auscultación Sísmica y Volcánica Instituto Costarricense de Electricidad (ICE) • Sección de Sismología, Universida de Oriente (UCR) • Universidad Nacional, Campus Omar Dengo (HDC)

  27. Seismic Networks Covering the Caribbean Region CENTRAL AMERICA (Cont’d) • Instituto Nacional de Sismología, Vulcanología, Meteorología e Hidrología - INSIVUMEH (GCG) • Instituto Nicaragüense de Estudios Territoriales – INETER • Universidad Nacional Autónoma de Honduras (UNAH) MEXICO • Red Sismológica Nacional de México - MNSN (MX) • Servicio Sismológico Nacional, Instituto de Geofísica, UNAM GLOBAL • Global Seismic Network, Albuquerque Seismological Laboratory, US • Comprehensive Test Ban Treaty IMS • French GEOSCOPE Network

  28. Nicaraguan Net Use of Digital BB Instrumentation in Sub-regional Seismic Networks SRU Net in the EC Venezuelan Net

  29. - USGS Albuquerque Seismological Laboratory - IRIS/IDA Group at IGPP, Scripps Institution of Oceanography University of California, San Diego - University Networks and Affiliates Global Networks IRIS/USGS GLOBAL NETWORK

  30. French GEOSCOPE Network

  31. Existing and Planned Real-Time Broadband Seismic Network Bahamas Turks and Caicos Is. Mexico Cayman Is. Puerto Rico Haiti Dom. Rep Jamaica Belize Guadeloupe Honduras Dominica Aves Is. Guatemala Martinique Nicaragua St. Lucia El Salvador St. Vincent San Andres Is. Grenada Barbados Tobago Trinidad Costa Rica Panama Cocos Is Colombia Proposed GSN Stations Various Existing local BB Stations Proposed USAID/GOTT/UWI Sub-Net Network Proposed at RSNO Workshop Proposed Dutch Antillean Sub-Net Proposed Cayman Sub-Net Existing GSN Stations

  32. Key Closing Points Modern Seismological Instrumentation • Are very sensitive and can represent ground motion very accurately • More qualitative research • Remain on-scale for large events. Data can be processed rapidly • Applicable for Early Warning Systems • Instrument networks are more scalable and versatile • Can support the operation of multiple monitoring applications • Easy to extend coverage beyond national boundaries

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