J R Kayal Formerly: Head (Gepphysics), Geol Surv India

CSIR Emeritus Scientist, Jadavpur University, Kolkata& Adjunct Professor, Indian School of Mines, Dhanbad

Seismic Environments in Northeast India Region: An Appraisal

1997

19931967

Tibet

India

Kyona Killari

JabalpurBhuj

Large and Great Earthquakes in Indian Sub-continent

Kayal, 2008

IMD, 2005

Earthquakes at the Burma-Andaman-Sumatra-Java Subduction Zone

Rao et al., 2006

Tectonic Map of Northeast India Region

Kayal et al., 2006

Isoseismal map of the 1897 great Shillong Earthquake (Oldham, 1899)

Picture showing the up thrown boulders (Oldham, 1899).

Kayal, 2010, GNHR

(a) Isoseismal map of the 1950 Assam Great earthquakeTandon, 1954).

Inset: Damaged bridge in the maximum Intensity zone (Poddar, 1950).

(b) Fault plane solutions of the earthquakes in the Assam syntaxis zone (Holt et al.,1991)

Kayal, 2010, GNHR

Tectonic Evolution in NE India Region

Nandy, 2001

Regional Seismicity (1964-96) in NE India Region

Data source : USGS, 1964-1996

Kayal, 1998, J Geophys

Gravity Map of Northeast India Region

Kayal, 1998, J Geophys

15

16

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19

20

21

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23

24

25

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27

28

29

30

0 100 200

Depth (Km)

Lat

itu

de

ArunachalPradesh

Upper Assam

Nagaland

Manipur

Mizoram(Eastern)

Bagan(Myanmar)

Irrawaddy(Myanmar)

(b)

Sanoujam, Kayal, Arefiev et al., 2009

EHB relocated events: 1980-2007

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

Zone C

Kopili Fault Naga Thrust CBB

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

Zone B

Sagaing Fault

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

Zone D

Meghalaya EBT Sagaing Fault

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

Zone E

Sagaing FaultBangladesh

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

Zone G

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

0

Zone F

Mizoram

0

50

100

150

200

90 91 92 93 94 95 96 97 98 99 100

Zone A

A

B

C

D

E

F

G

CBB

CBB

CBB

CMT

EBT

Sagaing Fault

Sagaing Fault

Sagaing Fault

Section parallel to Lohit & Mishmi thrusts

Sagu (Myanmar)

Sanoujam, Kayal, Arefiev et al., 2009

Degree East

Degree North

Sanjoum, Kayal, Arefiev et al., 2009

3D view of the Subduction zone below IBR

Rao & Kalpana, 2005, GRL

Subduction Tectonics: Indo Burma range

Microseismicity Map of Northeast India: Local Network Data (1982-1992)

Kayal, 2008

Microseismicity recorded by local networks (RRL-J/NGRI Bulletin 1993-1999)

Bhattacharya & Kayal 2002

Microseismicity Map of NE India (1993-99)

(Bhattacharya & Kayal, 2002

b-value Mapping in Shillong Plateau Region (1993-99)

9 0 . 5 9 1 9 1 . 5 9 2 9 2 . 5 9 3 9 3 . 5 9 4 9 4 . 52 5

2 5 . 5

2 6

2 6 . 5

2 7

2 7 . 5

2 8

0 . 3

0 . 4

0 . 5

0 . 6

0 . 7

0 . 8

0 . 9

1

K o p i l i L i n e a me n t

S h i l l o n g P l a t e a u

U p p e r A s s a m V a l l e y

Bhattacharya & Kayal, 2002

Fractal Dimension Mapping in Shillong Plateau Region (1993-99)

9 0 . 5 9 1 9 1 . 5 9 2 9 2 . 5 9 3 9 3 . 5 9 4 9 4 . 52 5

2 5 . 5

2 6

2 6 . 5

2 7

2 7 . 5

2 8

0 . 8

1

1 . 2

1 . 4

1 . 6

1 . 8

K o p i l i L i n e a me n t

S h i l l o n g P l a t e a u

U p p e r A s s a m V a l l e y

Bhattacharya & Kayal, 2002

2~)( DrrC

Seismic Images beneath the Shillong Plateau Region (1993-99)

(Bhattacharya & Kayal et al., 2007, AJES)

9 1 9 2 9 3 9 4 9 5

2 4

2 5

2 6

2 7

2 89 1 9 2 9 3 9 4 9 5

2 5

2 6

2 7

2 4

2 8

[ 5 - 1 5 k m ] [ 1 5 - 2 5 k m ]

[ 2 5 - 3 5 k m ] [ 3 5 - 4 5 k m ]

[ 1 0 k m ] [ 2 0 k m ]

[ 3 0 k m ] [ 4 0 k m ]

+ 1 5 %

- 1 5 %

0

M H

M B T

MC T

D F

D T

N T

S P

M H

KL

D F

S P

M H

M B T

M C T

D F

D T

N T

S P

M HKL

M B T

MC T

D F

D T

N T

S P

KL

+ 2 0 %

- 2 0 %

0

+ 5 %

+ 5 %

Pop-up Tectonic Model: Shillong Plateau

(Kayal et al, 2006, Curr Sci.)

(Bilham & England, 2001, Nature)

Fault plane solutions of recent earthquakes (2000-2009)

Kayal, Arefiev, Dorbath et al., 2011 (submitted).

(a) Pop-up Tectonic Model, Bilham & England, 2001

(b) Depth section of the events across the Shillong Plateau

© The fault planes at depth

Kayal, Arefiev, Dorbath et al., 2011 (submitted)

Transverse Tectonics along the Kopili fault

Kayal, Arefiev, Dorbath et al., 2011(submitted)

Paleoseismic Evidences at the Epicentre Zone: 1897 Shillong Earthquake

(Sukhija et al., 1999, Tectonophys)Recurrence period : 500 + 100 yrs

Kayal , Arefiev et al., 2010, GNHR

Recent Two Felt Earthqukes in NE India Region

Kayal , Arefiev et al., 2010, GNHR

The Two Recent Felt EQs on the Kopili Fault

Assam Valley EQ: Mw 5.4Aug 19, 2009

& Bhutan Him EQ: Mw 6.3Sept 21, 2009

Teleseismic stations used for Moment Tensor solutions

THANK YOU !

Tista River, Sikkim Himalaya