Review regional Source Specific Station Corrections (SSSCs) developed for northern Eurasia

Enter Division/Section(In View>Master>Slide Master) August 25, 2013

1.06.2004

I. Kitov ( IDC/SR/RF)

Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty OrganizationProvisional Technical SecretariatVienna International CentreP.O. Box 1200A-1400 ViennaAUSTRIAEmail address

Review regional Source Specific Station Corrections (SSSCs) developed for northern Eurasia


Review regional Source Specific Station Corrections (SSSCs) developed for northern Eurasia

1. To evaluate current version of SSSCs installed at IDC (Russian Federation-United States Joint Calibration Program)

2. To test and evaluate various sets of SSSCs with highest emphasis in GT0-2 explosions

3. To develop procedures for SSSCs validation4. To study location problem in presence of correlated errors

and deviations from Gaussian statistics5. To select sets or subsets of proposed SSSCs for installation

into routine IDC processing (CTBT/WGB/TL-2/76, 7 August 2003)

Are SSSCs necessary?

Objectives:


2Review regional Source Specific Station Corrections (SSSCs) developed northern Eurasia

Requirements for regional location by IMS network : - Improve of location accuracy (Objectives :1-5) - Increase of GA processing efficiency(Objectives : 1-5) Description of regional SSSCs sets for northern Eurasia (IDC, Lamont, SAIC) (Objectives : 2,3,5) Comparison of location results for UNE (IASPEI and Lamont) - Full arrival sets (Objectives : 2,3,4) - IMS substitute stations (Objectives : 1-3,5) - Simulation of sparse seismic network (Objectives : 2,3,4) Comparison of location results for REB and SEL3 (IASPEI, IDC, Lamont, SAIC) (Objectives : 1,3-5) Findings and conclusions

Outline

Enter Division/Section(In View>Master>Slide Master)

August 25, 2013

Regional location by IMS network

Requirements 1. Location Accuracy 1000 km sq. and <50 km major axis2. GA processing As many valid regional events in SEl1-SEL3 as possible

(1D global model may not be adequate at regional level to fulfill the requirements


August 25, 2013

Sets of SSSC for northern Eurasia

1. IDC velocity model and SSSCs (Pn, Sn, Pg)(Russian Federation-United States Joint Calibration Program)2. Group1 IMS stations - Lamont Consortium SSSCs (Pn, Sn)3. Group1 IMS stations - SAIC Consortium SSSCs (Pn, Sn)

Common stations for which SSSCs sets are available: AAK,AKTO,BIL,BOD,BVAR,KURK,MA2,MKAR, NRIS,PDYAR,SEY,TIXI,URG,USK,YAK,ZAL


August 25, 2013

F S U UNE and seismic network (FSU,IMS)

Map –stations, UNE Red triangle - IMS

Black triangle - FSUBlue cross - UNE


August 25, 2013

Comparison of location results with various sets of SSSCs

1. Location of underground nuclear explosions (GT0-GT2) IASPEI vs. Lamont vs. Lamont kriged

1.1. Peaceful Nuclear Explosions (PNE)1.2. Semipalatinsk Test Site (STS)1.3. Simulation of IMS network1.4. Simulation of sparse seismic network

IASPEI vs. IDC (not available for comprehensive set)IASPEI vs. SAIC (not available / offer of 15K$)2. Location of earthquakesIASPEI - IDC - Lamont - Lamont kriged - SAIC

2.1. REB2.2. SEL3


August 25, 2013

Lamont-Lamont kriged SSSCs comparison: PNEs - all arrivals

Lamont kriged : Improvement in 45 from 52 cases (86%) In 45 from 52 cases (86%) inside 17 km radius

Lamont kriged presents Lamont SSSCs in the following work


August 25, 2013

IASPEI -Lamont kriged SSSCs comparison: PNEs - all arrivals

Mislocation of selected UNE; range <20 degIASPEI model

mean=14.6 km; stdev=7.7 km, median=14.1 km

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Mislocation of selected UNE; range <20 degIASPEI model, fixed depth

mean=16.4 km; stdev=9.2 km, median=15.7 km

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Mislocation of selected UNE; range <20 degLamont Kriged SSSC's

mean=9.0 km, stdev=8.8 km, median=6.4 km

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Mislocation of selected UNE; range <20 degLamont Kriged SSSC's, fixed depth


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SSSCs provide higher location accuracy


August 25, 2013

IASPEI - Lamont kriged SSSCs travel time residual comparison: PNEs - all arrivals

Normal distribution(0.18,1.88)

IASPEI – normal

Lamont - exponential

Fixed at GT0

Fixed at GT0

Fixed depth solution

Fixed depth solution


August 25, 2013

IASPEI -Lamont -Lamont kriged SSSCs location comparison STS

NORTHERN EURASIAMislocation of STS UNE; range <20 deg

IASPEI modelmean=20.1 km; stdev=8.9 km, median=19.4 km

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Mislocation of STS UNE; range <20 degLamont Kriged SSSC's


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Lamont kriged SSSCs provide the highest accuracy of location of STS explosions


August 25, 2013

IASPEI - Lamont kriged SSSCs location comparison STS

NORTHERN EURASIAComparison of mislocation STS UNE

IASPEI vs. Lamont SSSC's

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Improvement in 66 from 72 cases (92%)In 61 from 72 cases (85%) inside 17 km radius

IASPEI - 31 from 72 inside 17 km radius


August 25, 2013

IMS network simulation IASPEI -Lamont kriged SSSCs location comparison

PNEs – 3 station sets (1826 sets)criteria: from PNEs data set;

< 3 deg. from IMS station; > 7 deg. between stations

Mislocation - Lamont kriged SSSC- 3 IMS substitute stations events; mean=90 km, stdev=126 km

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Mislocation - IASPEI model- 3 IMS substitute stations events; mean=92 km, stdev=138 km

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No visible improvement in IMS substitute stations locationIDC validation test excluded all “outliers”


August 25, 2013

FSU, IMS seismic networks and selected PNEs


August 25, 2013

IASPEI -Lamont kriged SSSCs location comparison: Azgir-5Simulation of sparse network – all 5 station sets with >7 deg between the stations

SSSCs result in : Lower mislocation – same scattering

Red square - gravity centerYellow triangle - full station set location


August 25, 2013

IASPEI -Lamont kriged SSSCs location comparison: OkaSimulation of sparse network

SSSCs result in : Larger mislocation – same scattering


August 25, 2013

IASPEI -Lamont kriged SSSCs location comparison: Craton-2Simulation of sparse network

SSSCc result in: Same mislocation – same scattering


August 25, 2013

IASPEI -Lamont kriged SSSCs location comparison: Grifon-1 and -2Simulation of sparse network


August 25, 2013

IASPEI -Lamont kriged SSSCs location comparison: PamukSimulation of sparse network


August 25, 2013

IASPEI -Lamont kriged SSSCs travel time residuals comparison : sparse network simulation

IASPEI – normal

Lamont - exponential

What Mechanisms doRespond forExponential Distribution?


August 25, 2013

Earthquakes - Pn residuals at NE IMS stationsIASPEI / IDC / Lamont kriged / SAICREB and SEL3 - event selection criteria

1. Only events with Pn phases at IMS stations under study2. Only events without Pn/Pg/Sn at IMS stations with installed SSSCs, but not under study(ARCES, FINES,OBN

…)3. All defining parameters used as are (travel time, azimuth, slowness, deltime, delaz, delslo)

2057 – REB events5012 – SEL3 events


August 25, 2013

Earthquakes - Pn residuals at NE IMS stationsIASPEI / IDC / Lamont kriged / SAIC

REB and SEL3 - Results Overview

BULLETIN REB REB REB SEL3 SEL3 SEL3MODEL MEAN STDEV MEDIAN MEAN STDEV MEDIANIASPEI 0.5 1.36 0.56 -0.12 3.00 -0.06IDC (Pn) 0.39 1.10 0.24 -0.13 1.79 -0.07IDC(ALL) 0.22 1.19 0.07 -0.43 2.26 -0.16LAMONT(Pn,kriged) 0.14 1.05 0.17 -0.29 2.3 -0.10SAIC -0.01 0.97 0.03 -0.19 1.97 -0.07

High mean for REB – IASPEI, IDC(Pn)High mean for SEL3 – IDC(All), Lamont (kriged)


August 25, 2013

Earthquakes - Pn residuals at NE IMS stationsIASPEI -IDC- Lamont kriged - SAIC

REB

Pn travel time residuals from earthquakes LocSAT; IASPEI model; REB ; nphase=2057

mean=0.50 sec, stdev=1.36 sec; median=0.56 sec

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Pn travel time residuals from earthquakes LocSAT; IDC model (only Pn SSSCs); REB; nphase=2057;


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IIIASPEI : Larger mean, stdev – closer to normal distribution

Normal distribution (0.5, 1.36) Normal distribution (0.39, 1.10)


August 25, 2013


REBPn travel time residuals from earthquakes LocSAT; IDC model;

REB; all phases;nphase=2057mean=0.22 sec, stdev=1.19 sec; median=0.07 sec

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Pn travel time residuals from earthquakes LocSAT; Lamont kriged SSSC; REB; nphase=2057mean=0.14 sec; stdev=1.05 sec; median=0.17 sec

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Pn travel time residuals from earthquakes LocSAT; SAIC SSSC; REB; nphase=2057

mean=-0.01 sec; stdev=0.97 sec; median=0.03 sec

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Pn travel time residuals from earthquakes LocSAT; IDC model (only Pn SSSCs); REB; nphase=2057;


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August 25, 2013


SEL3

Pn travel time residuals from earthquakes LocSAT; IASPEI model; SEL3 ; nphase=5710

mean=-0.12 sec, stdev=3.00 sec; median=-0.06 sec

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IASPEI : Larger stdev – lower mean value

Pn travel time residuals from earthquakes LocSAT; IDC model; SEL3; all phases;nphase=5712


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August 25, 2013


SEL3 Pn travel time residuals from earthquakes LocSAT; IDC model

(only Pn SSSCs); SEL3; nphase=5712mean=-0.13 sec, stdev=1.79 sec; median=-0.07 sec

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Pn travel time residuals from earthquakes LocSAT; IDC model; SEL3; all phases;nphase=5712


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Pn travel time residuals from earthquakes LocSAT; Lamont kriged SSSC; SEL3; nphase=5711mean=-0.29 sec; stdev=2.30 sec; median=-0.10 sec

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Pn travel time residuals from earthquakes LocSAT; SAIC SSSC; SEL3; nphase=5712

mean=-0.19 sec; stdev=1.97 sec; median=-0.07 sec

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August 25, 2013

MAIN FINDINGS AND CONCLUSIONS

1. Location of PNEs with SSSC is more accurate if all available stations are used2. Three IMS substitute stations location is not accurate even if SSSCs are used3. Sparse network simulation reveals broader location scatteringwhen SSSCs are used4. SSSCs usage reduces scattering of residuals in REB and SEL3,with IDC implemented SSSCs (Pn, Sn, Pg) having the largest standard deviation among all available SSSCs sets


August 25, 2013

WHAT NEXT?

1. Location of PNEs with SSSC is more accurate if all available stations are used – SAIC AND IDC?2. Three IMS substitute stations location is not accurate even if SSSCs are used - SAIC AND IDC?3. Sparse network simulation reveals broader location scatteringwhen SSSCs are used - SAIC AND IDC?4. SSSCs usage reduces scattering of residuals in REB and SEL3,with IDC implemented SSSCs (Pn, Sn, Pg) having the largest standard deviation among all available SSSCs sets

Review regional Source Specific Station Corrections (SSSCs) developed for northern Eurasia

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