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 validation 4. To study location problem in presence of correlated errors and deviations from Gaussian statistics 5. To select sets or subsets of proposed SSSCs for installation into routine IDC processing

1. Enter Division/Section(In View>Master>Slide Master) August 25, 2013 Page 1
1.06.2004
I. Kitov ( IDC/SR/RF)
Preparatory Commission for the Comprehensive
Nuclear-Test-Ban Treaty Organization
Provisional Technical Secretariat
Vienna International Centre
P.O. Box 1200
A-1400 Vienna
AUSTRIA
Email address
Review regional Source Specific Station
Corrections (SSSCs) developed for northern
Eurasia

2. Enter Division/Section(In View>Master>Slide Master) August 25, 2013 Page 2
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 validation
4. To study location problem in presence of correlated errors
and deviations from Gaussian statistics
5. 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
:

3. Enter Division/Section(In View>Master>Slide Master) August 25, 2013 Page 3
2
Review 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

4. Regional location by IMS network
Requirements
1. Location Accuracy
1000 km sq. and <50 km major axis
2. 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

5. 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

6. F S U UNE and seismic network (FSU,IMS)
Map –stations,
UNE Red triangle - IMS
Black triangle - FSU
Blue cross - UNE

7. 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 network
1.4. Simulation of sparse seismic network
IASPEI vs. IDC (not available for comprehensive set)
IASPEI vs. SAIC (not available / offer of 15K$)
2. Location of earthquakes
IASPEI - IDC - Lamont - Lamont kriged - SAIC
2.1. REB
2.2. SEL3

8. 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

9. IASPEI -Lamont kriged SSSCs comparison:
PNEs - all arrivals
Mislocation of selected UNE; range <20 deg
IASPEI model
mean=14.6 km; stdev=7.7 km, median=14.1 km
-60
-40
-20
0
20
40
60
-60 -40 -20 0 20 40 60
longitude, km
lattitude,km
Mislocation of selected UNE; range <20 deg
IASPEI model, fixed depth
mean=16.4 km; stdev=9.2 km, median=15.7 km
-60
-40
-20
0
20
40
60
-60 -40 -20 0 20 40 60
longitude, km
lattitude,km
Mislocation of selected UNE; range <20 deg
Lamont Kriged SSSC's
mean=9.0 km, stdev=8.8 km, median=6.4 km
-60
-40
-20
0
20
40
60
-60 -40 -20 0 20 40 60
longitude, km
lattitude,km
Mislocation of selected UNE; range <20 deg
Lamont Kriged SSSC's, fixed depth
mean=10.7 km, stdev=11.2 km, median=7.4 km
-60
-40
-20
0
20
40
60
-60 -40 -20 0 20 40 60
longitude, km
lattitude,km
SSSCs provide higher location
accuracy

10. 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

11. IASPEI -Lamont -Lamont kriged SSSCs location comparison
STS
NORTHERN EURASIA
Mislocation of STS UNE; range <20 deg
IASPEI model
mean=20.1 km; stdev=8.9 km, median=19.4 km
-60
-40
-20
0
20
40
60
-60 -40 -20 0 20 40 60
longitude, km
lattitude,km Mislocation of STS UNE; range <20 deg
Lamont Kriged SSSC's
mean=13.5 km, stdev=10.4 km, median=10.5 km
-60
-40
-20
0
20
40
60
-60 -40 -20 0 20 40 60
longitude, km
lattitude,km
Lamont kriged SSSCs provide the highest accuracy of location of
STS explosions

12. IASPEI - Lamont kriged SSSCs location comparison
STS
NORTHERN EURASIAComparison of mislocation STS UNE
IASPEI vs. Lamont SSSC's
0
5
10
15
20
25
30
35
40
45
50
0 10 20 30 40 50
IASPEI mislocation, km
LamontSSSCmislocation,km
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

13. 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
-200
-150
-100
-50
0
50
100
150
200
-200 -100 0 100 200
lon, km
lat,km
Mislocation - IASPEI model- 3 IMS substitute stations
events; mean=92 km, stdev=138 km
-200
-150
-100
-50
0
50
100
150
200
-200 -100 0 100 200
lon, km
lat,km
No visible improvement in IMS substitute stations location
IDC validation test excluded all “outliers”

14. FSU, IMS seismic networks and selected PNEs

15. IASPEI -Lamont kriged SSSCs location comparison: Azgir-5
Simulation of sparse network –
all 5 station sets with >7 deg between the stations
SSSCs result in : Lower mislocation – same scattering
Red square - gravity center
Yellow triangle - full station set location

16. IASPEI -Lamont kriged SSSCs location comparison: Oka
Simulation of sparse network
SSSCs result in : Larger mislocation – same scattering

17. IASPEI -Lamont kriged SSSCs location comparison: Craton-2
Simulation of sparse network
SSSCc result in: Same mislocation – same scattering

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

19. IASPEI -Lamont kriged SSSCs location comparison: Pamuk
Simulation of sparse network

20. IASPEI -Lamont kriged SSSCs travel time residuals comparison :
sparse network simulation
IASPEI – normal
Lamont - exponential
What
Mechanisms
do
Respond
for
Exponential
Distribution?

21. Earthquakes - Pn residuals at NE IMS stations
IASPEI / IDC / Lamont kriged / SAIC
REB and SEL3 - event selection criteria
1. Only events with Pn phases at IMS stations under study
2. 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 events
5012 – SEL3 events

22. Earthquakes - Pn residuals at NE IMS stations
IASPEI / IDC / Lamont kriged / SAIC
REB and SEL3 - Results Overview
BULLETIN REB REB REB SEL3 SEL3 SEL3
MODEL MEAN STDEV MEDIAN MEAN STDEV MEDIAN
IASPEI 0.5 1.36 0.56 -0.12 3.00 -0.06
IDC (Pn) 0.39 1.10 0.24 -0.13 1.79 -0.07
IDC(ALL) 0.22 1.19 0.07 -0.43 2.26 -0.16
LAMONT(Pn,kriged) 0.14 1.05 0.17 -0.29 2.3 -0.10
SAIC -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)

23. Earthquakes - Pn residuals at NE IMS stations
IASPEI -IDC- Lamont kriged - SAIC
REB
Pn travel time residuals fromearthquakes LocSAT;
IASPEI model; REB ; nphase=2057
mean=0.50 sec, stdev=1.36 sec;median=0.56 sec
-100
0
100
200
300
400
500
600
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals fromearthquakes LocSAT; IDC model
(onlyPn SSSCs);REB; nphase=2057;
mean=0.39 sec, stdev=1.10 sec; median=0.24 sec
-200
0
200
400
600
800
1000
1200
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
IIIASPEI : Larger mean, stdev – closer to normal distribution
Normal distribution (0.5, 1.36) Normal distribution (0.39, 1.10)

24. Earthquakes - Pn residuals at NE IMS stations
IASPEI -IDC- Lamont kriged - SAIC
REB
Pn travel time residuals from earthquakes LocSAT; IDC model;
REB; all phases;nphase=2057
mean=0.22 sec, stdev=1.19 sec; median=0.07 sec
-200
0
200
400
600
800
1000
1200
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals from earthquakes
LocSAT; Lamont kriged SSSC; REB; nphase=2057
mean=0.14 sec; stdev=1.05 sec; median=0.17 sec
-200
0
200
400
600
800
1000
1200
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals from earthquakes
LocSAT; SAIC SSSC; REB; nphase=2057
mean=-0.01 sec; stdev=0.97 sec; median=0.03 sec
-200
0
200
400
600
800
1000
1200
1400
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals from earthquakes LocSAT; IDC model
(only Pn SSSCs); REB; nphase=2057;
mean=0.39 sec, stdev=1.10 sec; median=0.24 sec
-200
0
200
400
600
800
1000
1200
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin

25. Earthquakes - Pn residuals at NE IMS stations
IASPEI -IDC- Lamont kriged - SAIC
SEL3
Pn travel time residuals fromearthquakes LocSAT;
IASPEI model; SEL3 ; nphase=5710
mean=-0.12 sec, stdev=3.00 sec; median=-0.06 sec
0
200
400
600
800
1000
1200
1400
1600
1800
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
IASPEI : Larger stdev – lower mean value
Pn travel time residuals fromearthquakes LocSAT; IDC model;
SEL3; all phases;nphase=5712
mean=-0.43 sec, stdev=2.26 sec; median=-0.16 sec
0
500
1000
1500
2000
2500
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin

26. Earthquakes - Pn residuals at NE IMS stations
IASPEI -IDC- Lamont kriged - SAIC
SEL3
Pn travel time residuals from earthquakes LocSAT; IDC model
(only Pn SSSCs); SEL3; nphase=5712
mean=-0.13 sec, stdev=1.79 sec; median=-0.07 sec
0
500
1000
1500
2000
2500
3000
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals from earthquakes LocSAT; IDC model;
SEL3; all phases;nphase=5712
mean=-0.43 sec, stdev=2.26 sec; median=-0.16 sec
0
500
1000
1500
2000
2500
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals from earthquakes
LocSAT; Lamont kriged SSSC; SEL3; nphase=5711
mean=-0.29 sec; stdev=2.30 sec; median=-0.10 sec
0
500
1000
1500
2000
2500
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin
Pn travel time residuals from earthquakes
LocSAT; SAIC SSSC; SEL3; nphase=5712
mean=-0.19 sec; stdev=1.97 sec; median=-0.07 sec
0
500
1000
1500
2000
2500
3000
-8 -6 -4 -2 0 2 4 6 8
tt residual, sec
##in1secbin

27. MAIN FINDINGS AND CONCLUSIONS
1. Location of PNEs with SSSC is more accurate if all
available stations are used
2. Three IMS substitute stations location is not accurate
even if SSSCs are used
3. Sparse network simulation reveals broader location scattering
when SSSCs are used
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

28. 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 scattering
when 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