seismic zone map of myanmar[2]

7/17/2019 Seismic Zone Map of Myanmar[2]

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SEISMIC ZONE MAP OF MYANMAR

(REVISED VERSION, 2005)

Explanatory Account

Dr. Maung Thein and U Tint Lwin Swe

February 2006

(Prepared under the auspices of Myanmar Earthquake Committee)

1. Introduction

This map is the revised version of the first seismic zone map of Myanmar prepared

by Dr. Maung Thein, Dr. Sone Han, U Tint Lwin Swe and Daw Tin Htay Mu in

August 2003, (Maung Thein et al., 2003). This revision was made by Dr. Maung

Thein, U Tint Lwin Swe, and Dr. Sone Han in December, 2005. This project is a

part of public service works by Myanmar Earthquake Committee in co-

operation with Myanmar Geosciences Society.

The main purpose is to have an updated and more probable seismic zone map,

thereby enhancing its reliability and usefulness. Also, it may be a fairly creditable

contribution to the World Seismic Safety Initiatives (WSSI) programme. It is hoped

that this map will be more than of academic and general interest as it is useful as

outlined in Section 5. Furthermore, it is also hoped that it may contribute to the

mitigation of earthquake hazards in Myanmar to some extent.

For easier comprehension and effective communication, title, subtitles and the

explanation on the map and the explanatory account are given in both English and

Myanmar Moreover a new column of general descriptions for the seismic zones is


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Large Earthquakes withinand near Myanmar(with dates and magnitudes)Locations are shown bycircled numbers

1. 23 May 1912 (8.0)2. 8 July 1918 (7.6)3. 27 Jan 1931 (7.6)4. 26 June 1941 (7.7)5. 12 Sept 1946 (7.5) 15 Sept 1946 (7.75)6. 29 July 1947 (7.9)7. 15 Aug 1950 (8.7)

1.

5.

3.

7.6.

2.

4.

INDIA PLATE

BUR

MA

PLATELET

THAILAND

CHINA

INDIA

BAN-

GLA-

DESH

AndamanRift

a

a

a

a

a

a

M 5

M 6

M 7

M 8

5.5 2.5

Plate motion in cm/yr

Subduction zone

Collision zone

Active spreading ridge

Thrust fault

5.52.5

3.2

5.5

2.5

Mandalay

Sittway

Myitkyina

Yangon

Keng Tung

LashioHaka

SagaingFault

a

a

a

a

a

a

a

a


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The seismic records show that there have been at least 16 major earthquakes with

magnitude (M) 7.0 within the territory of Myanmar in the past 170 years. Amongthese, the following four and 1975 Bagan Earthquake arranged chronologically, were

quite destructive: Innwa (Ava) earthquake of 23 March 1839 (M > 7.0), Maymyo

earthquake of 23 May 1912 (M 8.0), Bago (Pegu) earthquake of 5 May 1930 (M 7.3),

Sagaing earthquake of 16 July 1956 (M 7.0), and Bagan earthquake of 8 July 1975 (M

6.8).

The seismotectonics of Myanmar is shown in Figure 1. Earthquakes in Myanmar

have resulted from two main causes: (1) the continued subduction (with collision

only in the north) of the northward-moving Indian Plate underneath the Burma Platelet

(which is a part of the Eurasian Plate) at an average rate of 4.0 6.0 cm/yr; and (2) the

northward movement of the Burma Platelet from a spreading centre in the

Andaman Sea at an average rate of 2.5 3.0 cm/yr. Very large overthrustsalong the

Western Fold Belt have resulted from the former movement, and the Sagaing and

related faults from the latter movement. Intermittent jerks along these major active

faults have caused the majority of earthquakes in Myanmar. These seismotectonic

processes are still going on.

Figure 2 indicates that the occurrence of intermediate-focus earthquakes (focal

depth 70 300 km) along the Western Fold Belt is due to the subduction, and that ofshallow-focus earthquakes (focal depth 0 70 km) along the Central Lowlands and

Eastern Highlands is mainly due to shallow-depth strike-slip (e. g., Sagaing Fault) and

other faulting. Generally speaking, the shallow earthquakes tend to be more

destructive than intermediate ones for the same magnitude.

The major seismotectonically important faults in Myanmar are some unnamed

major thrust faults in northwestern Myanmar, Kabaw Fault along the Kabaw Valley in

western Myanmar, the well-known Sagaing Fault, and the Kyaukkyan Fault situated

east of Naungcho.

Here the well-known and seismologically very active Sagaing Fault deserves a


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Mandalay

Sittway

Myitkyina

Yangon

Keng Tung

LashioHaka


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that occurred on or near this large fault are (from north to south): Bago (1927, 1930-

M 7.3), Phyu (1930 M 7.3), Swa (1929), Pyinmana (1931), Innwa (1839 M > 7.0),Amarapura (1855), Mandalay (1871, 1931), Sagaing (1956 M 7.0), Tagaung (1991

M 7.3), Wuntho (1946 M 7.5), Myitkyina (1931 M 7.6), and Putao (1906)

In figure 3 is shown the apparent segmentation of the Sagaing Fault into three parts

on mainland Myanmar as indicated by the clusters of earthquake epicentres and

regionwise earthquake frequencies. These three segments correspond to the three

Zone V areas, namely, Bago-Taungoo, Mandalay-Sagaing-Tagaung, and Putao-

Tanaing areas. Two seismic gaps can be noted in Figure 3; one in the Yamethin-

Meiktila area, and another in the Bago area. During historical times, the former has

had low seismic activity, whereas the latter has had high seismic activity and a fairly

long history of earthquakes. In fact, Bago earthquake of 5 May 1930 was a very

destructive one. So, the Bago seismic gap (for the last 40 years) seems to suggest that

stress may have been accumulating for at least a moderate earthquake in the Bago

area.

3. Construction of the Map

This map is more refined and better supported by more seismic and seismotectonic

data and information together with some inferences. As in the previous map, the data

and information are of four kinds, with emphasis on i and ii.

i. Regional and local seismotectonics with special reference to major activefaults.

ii. Past earthquake data, records, and information including intensity maps

in MM scale, if available. (e. g., Maung Thein, 2001).


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4. Meanings in the Map

The map is a probable intensity zoning map. The approach is mainly empiricaland historical in the sense that it makes use of past seismic events and history to

make educated guesses about probable regionwise intensities in the future. (It is

hoped that a probabilistic seismic risk (or earthquake hazard) map based on horizontal

ground acceleration, which is preferred by design engineers, will be constructed in due

course).

As shown in the map, five seismic zones are demarcated and named (from low to

high) Zone I (Low Zone), Zone II (Moderate Zone), Zone III (Strong Zone), Zone

IV (Severe Zone), and Zone V (Destructive Zone), mainly following the

nomenclature of the European Macroseismic Scale 1992. (It should be mentioned that

in some countries, there are zones higher than Zone Vas used here). For each zone, a

probable range of ground acceleration in g values and equivalent Modified Mercalli(MM) Scale classes are given. The highest intensity zone designated for Myanmar is

the Destructive Zone (with probable intensity range of 0.4 0.5 g) which is

equivalent to MM class IX. There are four areas in that zone; namely, Bago-Phyu,

Mandalay-Sagaing-Tagaung, Putao-Tanaing, and Kale Myo-Homalin areas. The latter

two, however, would not have major earthquake hazards as they are only sparsely

populated.

Important cities and towns that lie in Zone IV (Severe Zone, with probable

intensity range of 0.3 0.4 g) are Taungoo, Taungdwingyi, Bagan-Nyaung-U,

Kyaukse, PyinOoLwin, Shwebo, Wuntho, Hkamti, Haka, Myitkyina, Taunggyi, and

Kunglong.

Yangon straddles the boundary between Zone II and Zone III, with the old andnew satellite towns in the eastern part in Zone III, and the original city in Zone II.

Regarding the probable range of ground acceleration (in g values; where 1.0 g =

980 cm/s2or 32 ft per second per second) expected in various seismic zones (Column

3 i E l i B ) i h ld b d h h f l i f i


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Table 1

Zone MM Classes Probable Damage Examples of Damage

V IX Major damage Considerable damage in specially

designed structures

Major damage in good RC buildings

IV VIII IX Considerable

damage

Considerable damage in good RC

buildings

Major damage in ordinary brick

buildings

III VIII Moderate damage Moderate damage in good RC buildingsConsiderable damage in ordinary brick

buildings

II VII Minor damage Minor damage in good RC buildings

Moderate damage in ordinary brick

buildings

I VI Slight damage Minor damage in ordinary brick

buildings

5.

Usefulness

The main uses of this map are as follows:

i. For educational purposes.


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References

GIAC, 1997.Report of Geodynamics of India and Asia Collision, GIAC Project.

GIAC, 2000.Report of Geodynamics of India and Asia Collision, GIAC Project.

Maung Thein, 2001. Mitigation and Earthquake Hazards in Myanmar (in Myanmar

with abstract in English).Jour. Myan. Acad. Tech.,v. 1, no. 2, p. 124 134.

Maung Thein, Sone Han, Tint Lwin Swe, Tin Htay Mu, 2003. Seismic Zone Map of

Myanmar (A3 size) with an explanatory note (9 p.)

NEIC, 2004. Earthquake data of Myanmar Region for 1964 2004.


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THAILAND

LAOS

V

III

II

II

II

IV

IV

I

CHINA

INDIA

BANGLADESH

V

V

V

III

III

III

IV

IV

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EXPLANATION

SEISMIC ZONE MAP OF MYANMAR

III

&Si f;v i f;az:jycsufEQUIVALENT

BAY OF BENGAL

GULF

OF

MOTTAMA

III

jrefrmEdki fi H i v si fZkefrsm;jyajryHk(jyi fqi fa&;qGJxm;aomyHk-2005)

(t jri fhqHk;a&mufEdki fonfhjyi f;x eft m;rsm;u dk wefzdk;rsm;ESi fh t wef;rsm;wdkYjzi fh

jyxm;onf/)g MM

(REVISED VERSION, 2005)

and MM classes)

(Shown with probable maximum intensities in g values

Sittway

Bagan

Bago

CoCo Island Dawei

Haka

Homalin

Pa-an

Kale Myo

Hkamti

Keng Tung

Lashio

Loikaw

Magway

Meiktila

Monywa

Muse

Myauk U

Myitkyina

Pathein

Putao

Pyay

PyinOoLwin

Pyinmana

Mandalay

Shwebo

Tachileik

Tagaung

Taungdwingyi

Taunggyi

Taungoo

Yangon

Sagaing

Phyu

Maubin

Thandwe

Hinthada

Bamaw

Mawlamyine

Wuntho

Kyaukse

Kunglong

0 50 100

miles

0 50 100 150 200

kmII

IV


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Figure 3. Apparent segmentation of the Sagaing Fault into three parts on mainland Myanmar as indicated by the

cluster of earthquake epicentres (left) and relative frequency of earthquake occurrences (right).Two

seismic gaps in the Yamethin-Meiktila and Bago areas can be noted. (Earthquakes with magnitude

5.0 for the period 1964-2004).

92.5 94 95.5 97 98.5 100

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Kawthaung

CoCo Island

Kalaewa

Kyaing Tone

Khanti

Tagaung

Tachilake

Taunggyi

Taungngu

Taungdwingyi

Dawei

Bagan

Pathein

Putao

Bago

Penlon

Pyinmana

Pyay

Hpa-an

Phyapon

Magway

Sagaing Mandalay

Meikhtila

Monywa

Mu-se

Pyin Oo Lwin

Myauk U

Myaung Mya

Myitkyina

Yangon

Shwebo

Myeik

Lashio

Loikaw

Haka

Homelin

0 5 10 15 20

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L

ONGITUD

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% FREQUENCY

M >= 5

M >= 6

M >= 7

M >= 8

LEGEND

LATITUDE

seismic zone map of myanmar[2]

Documents

probable seismic zone

seismic records

introductionthis map

bagan earthquake

sagaing earthquake

territory of myanmar

seismotectonics of myanmar

myanmar geosciences