joint interpretation of infrasound, acoustic, and seismic waves from meteorites: chelyabinsk bolide...

International Data Centre

Joint interpretation

of infrasound, acoustic, and seismic waves from

meteorites: Chelyabinsk bolide and other

events

I. Kitov, M. Rozhkov, D. Bobrov, and V. Ovtchinnikov

International Data Centre Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization Provisional Technical Secretariat Vienna International Centre P.O. Box 1200 A-1400 Vienna AUSTRIA Institute of Geosphere Dynamics, Russian Academy of Science, Moscow [email protected]


Outline

• Sources of signals

• Peak energy release. Acoustic (low-amplitude shock) wave

• Infrasound source vs. seismic source

• Seismic waves: Pn, Lg

• Acousto-seismic waves: LR, LQ

• Comparison with atmospheric nuclear tests: Love and Rayleigh waves

• Comparison with the 1987 Chulym and 2002 Vitim meteorites


Source and energy (discussed at AGU-2013)

Ek = mV2/2

m0 = 1.3 · 107 kg V0 = 1.9 ·104 m/s

Ek = 2.35 · 1016 J

Yield(1 kt TNT = 4.18 · 1012 J) = 560 kt Flight time ~20 s; Flight distance ~350 km Height of entry into atmosphere ~90 km Peak light emission ~ between 35 km and 25 km Peak shock wave ~ between 35 km and 20 km


Seismic source

(P2-P1)/P1 < 0.1 (high altitude explosion) P1 - surface atmospheric pressure; P 2 – shock wave pressure

ΔP(r,t)/P1 = (ΔP(R0)/P1 )max(1-ta/L+)exp(-ta/L+)

ΔP = P2-P1 ; R0 – radius of peak overpressure; t – time; a – sound speed near the surface; L+ - the length of shock wave

Shock wave


Source shape and evolution

Simplistic model

Real case evolution Olga P. Popova et al. Chelyabinsk Airburst, Damage Assessment,

Meteorite Recovery, and Characterization

Science 342, 1069 (2013)


Seismic observations: Pn


Location. SSSC- Source Specific Station Corrections

Pn : 55.06 º N, 60.92º E. Ellipse: Smaj=23.5 km, Smin =15.3 km

MKAR AKTO ARU

KURK BVAR


Seismic observations: Lg


Seismic observations: Lg waves magnitude estimation

5 stations: ARU, AKTO, BVAR, KURK, and MKAR

Station A, nm log(A) Δ, deg 0.83*log(Δ) Q=400, V=3.5,

f=0.5 Hz mLg

ARU 116 2.064 1.9 0.231 0.001 3.11 AKTO 39 1.591 5 0.580 0.004 2.98

BVAR 17.5 1.243 5.9 0.640 0.004 2.70

KURK 17.3 1.238 11.5 0.880 0.008 2.94

MKAR 12.2 1.086 15.8 0.995 0.012 2.90

mLg = log(A) + 0.81+ 0.83log(Δ) + γ(Δ-0.09)0.434 ; Nuttly, 1986

mLg = 2.93 ± 0.15


Seismic observations: LR

ARU

AKTO

BVAR

KURK

AAK

OBN

MKAR

KBZ


Seismic observations: LR magnitude estimation

# STA Phase Delta, deg Ms Ms res 1 BVAR LR 5.22 4.21 0.25

2 ZALV LR 13.53 4.35 0.39

3 AAK LR 14.17 4.11 0.15

4 OBN LR 14.65 3.20 -0.76

5 MKAR LR 14.91 4.35 0.39

6 KVAR LR 16.05 3.91 -0.05

7 KBZ LR 16.12 4.02 0.06

8 GNI LR 18.05 3.94 -0.02

9 NRIK LR 19.33 4.07 0.11

10 AKASG LR 20.07 4.06 0.11

11 FINES LR 20.23 3.23 -0.73

12 BRTR LR 23.79 3.72 -0.24

13 MLR LR 24.47 4.18 0.22

14 HFS LR 26.33 4.02 0.07

15 NOA LR 27.41 3.96 0.00

16 VRAC LR 28.05 4.00 0.05

17 SPITS LR 28.88 3.75 -0.21

18 GERES LR 29.95 4.21 0.26

19 EIL LR 31.17 3.87 -0.09

20 DAVOX LR 33.22 4.28 0.32

21 JMIC LR 34.09 3.71 -0.24

22 BORG LR 40.55 3.91 -0.05

23 CMAR LR 45.55 3.79 -0.17

24 KSRS LR 47.21 4.23 0.27

25 BBB LR 73.81 3.87 -0.09

25 IMS stations (also detected at ARU, AKTO, and KURK) Ms(IDC) = 3.95 ± 0.06 Ms(IDC)max = 4.35 (ZALV and MKAR) Ms(IDC)min =3.20 (OBN) Ms > Ms(DPRK2013)=3.9 Δmax= 74º !


Seismic observations, LQ

NRIK

SPITS


Atmospheric nuclear test: seismic observations, LQ

E-W

Z

time

LQ

LR

Δ =3660 km

1 min

From: Pasechnik, I.P. (1970). Characteristic of seismic waves from nuclear explosions and earthquakes, Nauka (in Russian)


Location

Pn : 55.06 º N, 60.92º E, Smaj=23.5, Smin=15.3 LR/LQ : 54.81º N, 62.23º E, Smaj=2.5 km, Smin =1.6 km (no modelling error) I : 53.52º N, 66.59º E, Smaj=376 km, Smin=197 km REB : 54.06º N, 61.80º E, Smaj=51 km, Smin=13 km

Disintegrated meteorite

impact zone.

Expected trajectory: yellow line

International Data Centre International Data Centre Page 15

Trajectories published

by Universidad de

Antioquia http://urania.udea.edu.co/sitios

/facom/research/chelyabinsk-

meteoroid.php?#

Location

http://urania.udea.edu.co/sitios/facom/research/chelyabinsk-meteoroid.php?






Trajectory by BS2013-IAU and YC2013-NASA, and Universidad

de Antioquia

Location


Chulym meteorite, 1984

26.02.1984, 13:40:00

57.5º N, 85.1º E

Ek ~10 kt

mLg = 3.39

Yield = 0.33kt

(From: Ovchinnikov and Pasechnik, Meteoritika 47,1988)


Vitim bolide, 2002

Expected Pn/Pg and Lg arrivals. No LR/LQ arrivals to be expected

due to sensor’s limited frequency range.

Infrasound arrivals at NLYR 3C station

24.09.2002, 16:48:56

57.91º N, 112.90º E Ek ~2.4 kt

(Adushkin, et al, 2004)

mLg = N/A

Yield = N/A

Data: a courtesy of Baykal Regional Seismic Network, Russian Academy of Sciences


Comparing Chulym, 1984, Chebarkul, 2013, and DPRK 2013 nuclear test

Mag Chulym Chelyabinsk Effect from

ML Not measured 2.4 Hitting the ground

MLg 3.31 2.93 Hitting the ground

Ms Not measured 3.95 Shock wave

What could we say about Chelyabinsk event if we would have only seismic observations?

“UNE case”:

• UNE manifestations at regional seismic stations: Pn, Lg and LR waves.

• Pn and LR locations give different coordinates and can’t be associated as a single source.

Comparing ML with the one determined by IDC from the DPRK-2013 event (ML(IDC)=4.5).

• The DPRK-2013 yield was around 10kt.

• The explosion yield is proportional to the signal amplitude measured when estimating a magnitude.

• From the magnitude measurements we can see that the Chel is almost 100 times smaller (2 magnitude units).

• The approximate yield of the explosion generating same body waves as Chel is 0.1 kt.



Mag Chulym Chelyabinsk Effect from

ML Not measured 2.4 Hitting the ground

MLg 3.31 2.93 Hitting the ground

Ms Not measured 3.95 Shock wave

If Chel were an atmospheric nuke.

• ATM test phenomena: prominent surface waves (Rayleigh and Love waves).

• UNE: a ratio R of energy transmitted to LR waves to total explosion energy is:

RUNE=ELR/EUNE = 10-6

RAIR= 4*10-8 for Air Nuclear Test

DPRK-2013: Ms = 3.9

• Chel event Ms = 3.95

DPRK-2013 was an underground explosion, Chel was an air explosion, so the equivalent yield of this meteor explosion must be 25 times higher than the DPRK-2013 test:

Ru/Ra = 25.

So the yield of the air explosion which would generate such waves must be 250Kt.



MLg discussion

• We estimated MLg=2.93 for Chelyabinsk event.

• To generate waves with such magnitude, UNE with the yield Y=0.2 kt must be conducted (according to Nuttly magnitude scale).

• Though the numbers for Pn and Lg magnitudes are different (0.1kt and 0.2kt), the yields estimated according to these magnitudes are really close taking into account uncertainties of M to Y conversion for Lg based measurements.

• Estimation of a kinetic energy corresponding to such explosion gives the mass of the space body remainder which has hit the ground between 1 and 100 t (the range is due to uncertain meteor velocity, etc.).

• Different mechanisms of wave generation (Pn and LR) in Chel and Chul cases produce difference in energy release as respectively 0.5 and 50:

MLg1 – MLg2 = 3.31 – 2.93 = 0.38 which corresponds approx. to yield ratio of 2.5 (2).

The meteorite energy estimated by us as ~500kt. Ovchinnikov and Pasechnik (1988) estimated Chulym meteor yield as 10 kT, so the shock wave energy ratio for these two events is 50.


Conclusions

• Just a small part of the meteorite hit the surface as debris.

• There were at least three sources separated in space and time: (1) infrasound, (2) LR and LQ, and (3) Pn, Sn, and Lg waves.

• These three sources are located along the meteorite trajectory.

• Lesson learned: atmospheric nuclear tests are excluded from CTBT seismic monitoring according to IDC rules (no LR associated for large Ms-mb differences, no LR associated without mb).


Thank You!

joint interpretation of infrasound, acoustic, and seismic waves from meteorites: chelyabinsk bolide...

Science

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