Towards a physical understanding of the mb M Event ... · I Event Screening is the rejection of H0 at a given signiﬁcance level, where the null hypothesis, H0, is that seismic (hydroacoustic,

Towards a physical understanding of themb:Ms Event Screening Criterion

Neil D. SelbyUK NDC

© 2015 British Crown Owned Copyright/MOD Page 1

Introduction

I Event Screening is the rejection of H0 at a givensignificance level, where the null hypothesis, H0, is thatseismic (hydroacoustic, infrasound) signals are from a singleexplosion source.

I mb :Ms is one of the four experimental provisional eventscreening criteria in use at the International Data Centre.

I mb :Ms is based on teleseismic body-wave magnitude mband surface wave magnitude Ms.

I Improving our understanding of the physical basis of mb :Msmay enable us to enhance screening performance.


Introduction

I Body-waves travel through the interior of the Earth, whilesurface waves are guided by the surface of the Earth.

I The basis of the mb :Ms criterion is that, in general,explosions generate smaller surface waves thanearthquakes with the same body-wave magnitude.


Body waves and surface waves


The mb:Ms plot

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7

body wave magnitude, mb

REB Events 2006

India 980511

Pakistan980528

China 960729

China 960608

China 950817

I Earthquakes: from IDC REB for 2006.

I India: mb from Bowers et al. 2002; Ms fromDouglas et al 2002.

I Pakistan: mb and Ms from Bowers et al. 2002.

I China: mb from pIDC REB; Ms from Bonneret al. 2006.


Original IDC Experimental Screening Line

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

India 980511

Pakistan980528

China 960729

China 960608

China 950817

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0

I Screening line: Fisk et al 2002.






DPRK 2006

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

India 980511

Pakistan980528

China 960729

China 960608

China 950817

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0

DPRK 061009

I DPRK 2006: UK NDC mb = 3.9, Ms = 2.8.(REB: mb = 4.1).







DPRK 2009

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

India 980511

Pakistan980528

China 960729

China 960608

China 950817

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0

DPRK 061009

DPRK 090525

I DPRK 2009: UK NDC mb = 4.6, Ms = 3.6.(REB: mb = 4.5, Ms = 3.6).




2012 Experimental Screening Line

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

India 980511

Pakistan980528

China 960729

China 960608

China 950817

IDC E

xper

imen

tal S

cree

ning

Line

M s =

mb −

0.6

4

DPRK 061009

DPRK 090525

I Screening line: Selby et al. 2012.




DPRK 2013

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

India 980511

Pakistan980528

China 960729

China 960608

China 950817

IDC E

xper

imen

tal S

cree

ning

Line

M s =

mb −

0.6

4

DPRK 061009

DPRK 090525

DPRK 130212


I Screening line: Selby et al. 2012.




NTS explosions

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

NTS Explosions

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0

I Explosion magnitudes from Selby et al.(2012).


East Kazakhstan explosions

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

NTS Explosions

East Kazakh Explosions

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0



Novaya Zemlya explosions

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

NTS

East Kazakh

NovayaZemlya

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0



Lop Nor explosions

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

NTS

East Kazakh

NovayaZemlya

Lop Nor

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0



FSU PNEs

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

NTS

East Kazakh

NovayaZemlya

Lop Nor

PNEs

Orig

inal

IDC E

xper

imen

tal S

cree

ning

Lin

e

M s =

1.2

5mb −

2.2

0

I Peaceful Nuclear Explosions in the FormerSoviet Union.



All

2

3

4

5

6

7

surf

ace

wav

e m

agni

tude

, Ms

2 3 4 5 6 7


REB Events 2006

NTS

East Kazakh

NovayaZemlya

Lop Nor

PNEs

IDC E

xper

imen

tal S

cree

ning

Line

M s =

mb −

0.6

4

DPRK 061009

DPRK 090525

DPRK 130212



Magnitude–yield relationships

2

3

4

5

6

7

mb

0 1 2 3 4

log10 Y

mb = 0.75log10 Y + 4

NTSFSU PNEsKazakhstan

2

3

4

5

6

7

Ms

0 1 2 3 4

log10 Y

Ms = log10Y + 2

I Explosion magnitudes from Selby et al. (2012).

I NTS yields from Springer et al. (2002).

I Nominal magnitude–yield relationships.



2

3

4

5

6

7

mb

0 1 2 3 4

log10 Y

mb = 0.75log10 Y + 4


2

3

4

5

6

7

Ms

0 1 2 3 4

log10 Y

Ms = log10Y + 2



I PNE yields from Sultanov et al. (1999).

I Nominal magnitude–yield relationships.

I Both mb and Ms higher for PNEs than NTS explosions of same yield.



2

3

4

5

6

7

mb

0 1 2 3 4

log10 Y

mb = 0.75log10 Y + 4


2

3

4

5

6

7

Ms

0 1 2 3 4

log10 Y

Ms = log10Y + 2



I PNE yields from Sultanov et al. (1999).

I Magnitude–yield relationships:I Mueller & Murphy (1971) model suggests mb-yield and Ms-yield

relationships should have the same slope.

I This does not seem to be the case for NTS.

I Both mb and Ms higher for PNEs than NTS explosions of same yield.

I For Kazakhstan, mb higher than NTS but Ms similar.

I Higher mb usually attributed to difference in t∗ .


Yield and depth

1.5

2.0

2.5

3.0

3.5

log 1

0h

0 1 2 3 4

log10Y

1.5

2.0

2.5

3.0

3.5

log 1

0h

0 1 2 3 4

log10Y

NTS explosions (blue) mostly at scaled depth, FSU PNEs (red) deeper, with no obvious relationship between depth and yield.

If mb and Ms scale differently with depth, could this, together with differences in t∗ , explain the difference in mb- and Ms-yieldrelationships between NTS and the PNEs?


Earthquake mb −Ms regional variability.

0.0 0.2 0.4 0.6 0.8 1.0

mb − Ms

I REB magnitudes 2010–

I Nb ≥ 10, Ns ≥ 10.

I Depth, h = 0.0.

I mb − Ms plotted atevent epicentre.


Ms path effects

-0.2 0.0 0.2

δγ

I Selby et al. 2003.


Questions

I Is the variation in mb-yield between NTS, Kazakhstan and thePNEs due to t∗?

I If so, what is the correct value of t∗ for DPRK?I Are the differences in Ms-yield between NTS/Kazakhstan and the

FSU PNEs due to the depth of burial?I Is the difference in the mb-yield and Ms-yield relationships for

NTS due to the scaled depth of burial?I What is the appropriate depth / depth-scaling for DPRK?

I Can the variability of earthquake mb:Ms values be reduced bycleverer measurements of mb and Ms?


ReferencesI Bonner J.L., Russell D.R., Harkrider D.G., Reiter D.T., and

Herrmann R.B., 2006. Development of a time-domain,variable-period surface-wave magnitude measurementprocedure for application at regional and teleseismicdistances, part II: application and Ms-mb performance. Bull.seism. Soc. Am. 96, 678–96.

I Bowers, D., Douglas, A., Selby, N.D., Marshall, P.D., Porter,D., and Wallis, N. J., 2002. Seismological identification of the1998 May 28 Pakistan nuclear test. Geophys. J. Int., 150,153-161.

I Douglas A., Selby N.D., and Bowers D., 2002. Seismicmagnitude and yield for the Indian nuclear test of 11 May1998. Current Science 83, 989-92.

I Fisk, M., D. Jepsen and J.R. Murphy, 2002. Experimentalseismic event-screening criteria at the PrototypeInternational Data Centre, Pure Appl. Geophys., 159,865-888.

I Selby, N.D., D. Bowers, P.D. Marshall and N.D. Selby, 2003.Empirical path and station corrections for surface-wavemagnitude, Ms, using a global network. Geophys. J. Int.,155, 379-390.

I Selby, N.D., P.D. Marshall, and D. Bowers, 2012. mb :Msevent screening revisited. Bull. seism. Soc. Am., 102,88-97.

I Springer, D.L., G.A. Pawloski, J.L. Ricca, R.F. Rohrer, andD.K. Smith, 2002. Seismic source summary for all U.S.below-surface nuclear explosions. Bull. seism. Soc. Am.,92, 1806-1840.

I Sultanov, D. D., J.R. Murphy, and Kh. D. Rubinstein, 1999. Aseismic source summary for Soviet peaceful nuclearexplosions. Bull. seism. Soc. Amer., 89, 640-647.


Documents

Towards a physical understanding of the mb M Event ... · I Event Screening is the rejection of H0 at a given signiﬁcance level, where the null hypothesis, H0, is that seismic (hydroacoustic,