presentation - PDF - Institute of Geodynamics Sabba S Stefanescu

EMSEV-DEMETER JOINT WORKSHOP IGRASINAIA, ROMANIABucharestSeptember 7-12, 72008GROUND - BASE MONITORING SYSTEM FORTHE NATURAL HAZARDS ASSESMENT DUE TOLANDSLIDE ACTIVITYD. A. STANICA, D. STANICA and C. DIACOPOLOSInstitute of Geodynamics of the Romanian AcademyBucharest – Romania, E-mail: Earmand@geodin.ro

OUTLINE:Landslides related to seismic events1. variables, indices and indicators for landslides;2. implementation and continuous improvement of thereal-time ground base monitoring system dependingon the landslide test sites conditions;3. innovation in integrated geo-sensors structure fornetwork conditions;4. real time signals processing for pattern recognitionin “pre disaster” and “at disaster” circumstances;5. assessment and quantification of the geodynamicprecursory parameters related to the landslidephenomena;6. provision of early-warning against the risk arisingfrom landslide process.

Variables, indices and indicatorsfor LandslidesVariablesIndicesIndicators•Geophysical:electromagnetic(perpendicular resistivity - ρ ┴ parallelresistivity - ρ ║, skew, strike, the hodographof the impedance tensor), DC-electric(apparent resistivity) and geomagnetic(Bzn);•Geological and geotechnical: lithologicaland structural features, tectonics, positionof morphological characteristics, terraingradient, internal friction angle, bulkdensity, plastic and liquid limit, particle sizedistribution, soil pH, etc.;•Hydro geological: groundwaterlevelscharacteristics, fluctuation and impact onthe slope stability;•Vegetation: impact of vegetation on slopestability, timber harvest impact, etc.•Climate: temperature, frequency andintensity of the rains and storms short andintense events;•Time series distribution ofthe geophysical, geological,geotechnical and climateparameters;•Statistical distribution ofhistorical events;•Arial and frequency-sizedistribution of landslides;•Frequency of earthquakesand tectonic processesassociated (active faults);•Identification of regularitiesor irregularities of eventswhich might facilitateprediction;•Changes in landscape of theaffected areas.•Anomalous behaviorof the geophysical,geological, geotechnicalandclimateparameters;•Realtimequantificationand dhierarchy of all thevariables in order toevaluate the riskfactorsandvulnerability;•Population,socio-economic and naturalenvironmentexposedto the landslides;•Loss of human andsocio-economicvaluesexposed to the risk.

Real-time ground basemonitoring systemSatelliteandGeologicaldataCentralSystem forProcessingDiagnose andDecisionRTG-BMSRESISTIVI-METERINTEL V3MAG-03DAM24bitADU - 0624bitLAB-VIEW16bitElectricfieldsensorsDCElectricandmagneticfieldsensors(lowfrequency)Electricandmagneticfieldsensors(high andlowfrequency)Crustalmovementssensors

SatelliteandGeologicaldataRESISTIVI-METERINTEL V3Data acquisition module forCentralSystem forProcessingDiagnose andDecisionMAG-03DAM24bitRTG-BMSADU - 0624bitLAB-VIEW16bitGeoElectric fieldFieldwork ConfigurationElectricfieldsensorsDCElectricandmagneticfieldsensors(lowfrequency)Electricandmagneticfieldsensors(high andlowfrequency)CrustalmovementssensorsResistivimeter (INTEL V3, Romania) is compact andself-contained thanks to an integrated receiver andtransmitter, with internal memory of 64 K, samplingrate of 0.2s, output power up to 200mA,communication trough serial interface enhanced byutility software for Windows

Data acquisition module for continuousmonitoring of the Geomagnetic fieldMAG-03DAMacquisition module6 channel, 24 bitresolution,samplingrateprogrammable,internal and externalbattery of 12 V , datastorage on laptop HD;Geomagnetic System Configuration3 axesmagneticsensorFrequencyrange: 3kH-DCSatelliteandGeologicaldataCentralSystem forProcessingDiagnose andDecisionRTG-BMSRESISTIVI-METERINTEL V3MAG-03DAM24bitADU - 0624bitLAB-VIEW16bitElectricfieldsensorsDCElectricandmagneticfieldsensors(lowfrequency)Electricandmagneticfieldsensors(high andlowfrequency)Crustalmovementssensors

SatelliteandGeologicaldataCentralSystem forProcessingDiagnose andDecisionRTG-BMSRESISTIVI-METERINTEL V3MAG-03DAM24bitADU - 0624bitLAB-VIEW16bitElectricfieldsensorsDCElectricandmagneticfieldsensors(lowfrequency)Electricandmagneticfieldsensors(high andlowfrequency)Crustalmovementssensors

Software ( MAPROS Packages)The following basic tasks are performed by MAPROS:Real time data acquisitionand processing ;Robust estimation of thetransfer functions;Real time display of timeseries and all important EM-parameters (ρ(║ ρ ┴ ,anisotropy, strike, skew,etc.);

Bzn disturbances linked to the seismic events1,8803.2 3.2 3.3 3.3 3.1 3.0 4.6 3.2 3.1 3.2 3.4 3.1 3.5 4.4 3.2 6.0124km 147 116km 164 142 145 166 148 crustal 149 140 123 148 171 100km1,8791,8781,8771,8761,8751,87401.09.200402.09.200403.09.200404.09.200405.09.200406.09.200407.09.200408.09.200409.09.200410.09.200411.09.200412.09.200413.09.200414.09.200415.09.200416.09.200417.09.200418.09.200419.09.200420.09.200421.09.200422.09.200423.09.200425.09.200426.09.200427.09.200428.09.200429.09.200430.09.200401.10.200402.10.200403.10.200404.10.200405.10.200406.10.200407.10.200408.10.200409.10.200410.10.200411.10.200412.10.200413.10.200414.10.200415.10.200416.10.200417.10.200418.10.200419.10.200420.10.200421.10.200422.10.200423.10.200424.10.200425.10.200426.10.200427.10.200428.20.200429.10.200430.10.200431.10.2004TIME [days]Bzn=Bz/Bperp.

THE NATURAL HAZARDS ASSESMENT DUE TOLANDSLIDE ACTIVITYGeoelectric models- DC 2D models;- EM 2D modelsPrecursory parameters:- Resistivity (parallel and perpendicular to the strike);- Electrical anisotropy ;- Skew and strikePrecursory phenomenon:- Low frequency electric signals that “arrive” before thetime derivative of the magnetic field, emitted prior thestress reached a critical value.

PROVITA VALLEYtest area for monitoring and diagnosisof typical landslides parametersACTIVE FAULTStanica, Tatu, 2005

PROVITA DE SUS- test site -for monitoring of the typical landslides parameters

DEPTH (AB/2)0.600.700.800.901.001.101.201.301.401.501.601.701.801.902.00DEPTH (AB/2 in m)D E P T H ( A B / 2 )0.600.700.800.901.001.101.201.301.401.501.601.701.801.902.000.600.700.800.901.001.101.201.301.401.501.601.701.801.902.002D specific geodynamic models2D specific geodynamic modelsGEOELECTRICAL (RESISTIVITY) CROSS-SECTIONProfile 1 - Provita Valley0 20 40 60 80 100 120 140[m]-10-20-30-40[m]24 20 15 10ρ a ( ohmm )Geoelectrical cross-sectionProfile 4 - Provita Valley-26NNW SSELENGTH (m)1 20 5 10 15 20 25 30 35 40 45 50 55 60-6SLIDE SURFACEACTIVE FAULT-10-20-30-40[m]Geoelectrical (resistivity) cross-sectionProfile 2 - Provita Valley0 20 40 60 80 100 120 140 160 180 200 220 [m]-4624 20 15 10ρ a ( ohmm )24 20 15 10ρ a ( ohmm )

PROVITA DE SUS- test site -for monitoring of the typical landslides parametersActive FaultEM ProfilesEM measurementpointSCHOOLHOUSE

2D- tomographic images (ρ(┴ B-polarized MODE)SSENNWACTIVE FAULTWSWENESLIDING SURFACE

PROVITA DE SUStest siteTOPOGRAPHICLANDMARK

ELECTRICAL ANIZOTROPYEA =│ρ xy/ρ yx│(normal field)30.09. 2005EA = │ρ ┴/ρ ║│(rotated field)1 207.10.20051 2

Skewness Parameterskewness =Zxx + ZyyZxy − Zyx30.09. 2005Skewness > 0.33D structure07.10.2005Skewness< 0.32D structure

STRIKE PARAMETER30.09. 200507.10.2005

Low frequency electric signals “arriving” before the timederivative of the magnetic field, emitted prior the stress toreach a critical valueD = 8 m

Low frequency electric signals “arriving” before the timederivative of the magnetic field, emitted prior the stress havereached a critical valueD= 8mD= 16m

SUMMARYGround-base monitoring system is able to:Investigate shallow and deep structure in order to elaboratethe adequate geodynamic models and electromagnetictomographies;Detect the active faults, geodynamic sutures and to draw upthe spatial distribution of the landslides;Evaluate the geoelectric pattern (before the stress reached acritical value) with the aim to identify the best placement forcontinuous monitoring;Reveal the short-term term precursory phenomena/parameters ofthe possible landslide events.

THANK YOU !Study supported by the Ministry ofEducation and Research, National Program“PN2”, Contract No.31-018/2007-2010