the geo-disaster mitigation measures in...

J. SE Asian Appl. Geol., Sep–Dec 2010, Vol. 2(3), pp. 144–154

THE GEO-DISASTER MITIGATION MEASURESIN MYANMAR

Kyaw Htun∗1

1Department of Engineering Geology, Yangon Technological University, Myanmar

Abstract

Myanmar has frequent geological disasters includ-ing earthquakes, tsunamis, landslides, and sub-sidences in karst area. Myanmar indeed is anearthquake-prone area as it lies in one of the twomain earthquake belts of the world, known as theAlpide Belt that extends from the Mediterraneanthrough Turkey, Iran, Afghanistan the Himalayasand Myanmar to finally Indonesia. Therefore,Myanmar is vulnerable to hazards from moder-ate and large magnitude earthquakes, includingtsunami hazards along its long coastal areas.

The seismotectonics of the region indicate thatearthquakes in Myanmar mostly originates alongan active subduction zone (Andaman MegathrustZone) in the West and along a large active trans-form fault zone (Sagaing Fault Zone) in the middlepart of the country. Local historic records and leg-ends also confirmed the fact that intermittent jerksalong these major active faults have caused the ma-jority of earthquakes in Myanmar. These seismotec-tonic processes are still going on. Along these faultzones stand many large urban cities where thick pop-ulations live in. Liquefaction is a very considerablefactor according to the past events in the water sat-urated area near the fault zones.

Geomorphologically, Myanmar has two moun-tainous provinces: namely, the Western Ranges andthe Eastern Highland. These provinces have inher-ently unstable nature among the areas of the coun-try. The steep slopes, unstable geologic conditionsand heavy rains combine together to make the moun-tainous regions one of the most hazard-prone areas

∗Corresponding author: KYAW HTUN, Departmentof Engineering Geology, Yangon Technological University,Myanmar. E-mail: [email protected]

in Myanmar. Landslides frequently happens in theseregions, disturbing the connection roads and infras-tructures rather than rural houses. Moreover, therehas been an increase in human settlement in hazard-prone areas as a result of rapid population growth,as well as improvement in accessibility by road andthe onset of other infrastructure development. Con-sequently, natural and man-made disasters are onthe increase and each event affects people more thanbefore. Even in central low land between the twomountainous ranges, landslide features occur alongthe bank of Ayeyarwady River and its tributaries.

There were also records of moderate tsunami gen-erated by two large magnitude earthquakes, whichoriginated in the Andaman-Nicobar Islands. Ofcourse, the tsunami generated by the giant 2004Sumatra Earthquake also caused moderate causali-ties in some parts of the Myanmar coast. Thus, it isevident that Myanmar is vulnerable to disaster frommoderate and large tsunamis along its long coastalline.

To mitigate loss of lives and damages of prop-erties, the Natural Disaster Mitigation Committeeof Myanmar has been formed since 2004. More-over, Seismic Hazard Zonation Map of Myanmarhas already been prepared with the collaboration ofengineering geologists, geoscientists and engineerssince 2006. During the year of 2006 to 2008, theMyanmar Geosciences Society (MGS) in collabora-tion with MEC has prepared the preliminary deter-ministic seismic zonation maps for four seismicallyhazardous cities.

Although modern seismological instruments andtechnical improvement are very essential, earth-quake resistant design code shall be enhanced bythe cooperative works among the scientists and en-gineers from various organizations. Landslide po-

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THE GEO-DISASTER MITIGATION MEASURES IN MYANMAR

tential map and tsunami inundation map are go-ing to be established this year. Moreover, to in-crease the awareness of the geo-disaster, educationand knowledge have been given to those who live inhazardous-prone areas by the collaboration of DMH,RRD, MES, MGS, ADPC and Universities in Yan-gon. Besides, landslide mitigation technology ap-plied in Myanmar and construction of tsunami shel-ter in coastal areas are also discussed in this paper.Keywords: Earthquake, tsunamis, active fault,landslide, liquefaction

1 Introduction

In recent times, Myanmar has experienced largemagnitude earthquakes and related hazards,frequent landslide phenomena and very rareoccasion of sink-hole and karst formation. Tec-tonically and geomophologically, Myanmar canbe subdivided into three provinces (MaungThein, 1993): namely, the Western Fold Belt(WFB) in the West, the Central Lowland (CL)in the middle, and the Eastern Highland (EH)in the East. Geologically, the WFB consistsmostly of very thick sequence of the flysch typesedimentary rocks and tectonic melange of ba-sic and ultrabasic rocks and exotic limestonein the form of ophiolite suite resulted by thesubduction of the Indian Plate underneath theBWurma Plate along the Bengal tectonic bound-ary. Continued collision between these twoplates also leads to the formation of high moun-tain arc in the East and Northwest parts ofMyanmar. Further East is the Eastern High-land which is a part of the Shan-Thai Block (alarge tectonic domain that connects the Pacifictectonic plate) and composed mainly of olderrock groups containing plateau limestone andmetamorphic complex. The fertile alluvial plainis the Central Lowland, intermittently croppedout by the mountain range and hills runningin North-South direction and also enhanced byMount Popa, a dormant volcano in its centralpart. A large active fault, the Sagaing Fault(Win Swe, 1981) is passing through the Easternmargin of this province. As an order of impor-tance, this paper will focus particularly on theearthquake and its related hazards and somelandslide hazard and their mitigation measures.

2 Research Methods

To identify the geo-hazards of the whole coun-try, tectonical, geomorphological, historicalevents of the disasters, satellite images of thecountry and its environments, GIS data, aerialphotographs of hazard-prone areas and postdisaster survey have been conducted. Takingconsideration upon these evidences, the deter-ministic seismic zone map of Myanmar andmajor cities, the potential area of landslides andtsunamis have been developed up to now.

Seismicity and seismotectonics of the region

Myanmar indeed is earthquake-prone as it liesin one of the two principal earthquake beltsof the world: the Alpide Belt. The seismo-tectonics of the Myanmar region is shown inFigure 1 (Thein and Swe, 2008). Earthquakesin the Myanmar region have originated fromtwo main causes: (1) the subduction (with colli-sion only in the North) of the northward mov-ing India Plate underneath the Burma Plate atan average rate of 4 to 6 cm/yr along the An-daman Mega-thrust Zone; (2) the northwardmovement of the Burma Plate from the spread-ing centre in the Andaman Sea at an averagerate of 2.5 to 3 cm/yr.

Very large over-thrusts along the WesternFold Belt have resulted from the former move-ment and the Sagaing and related faults fromthe later movement. Intermittent jerks alongthese major active faults have caused the major-ity of earthquakes in Myanmar. These seismo-tectonics processes are still going on. The earth-quakes that are generated by sea-floor spread-ing in the Andaman Sea, however, are mostlysmall to moderate in magnitude and shallow-focused.

The historical and seismic records show thatin addition to some major historical earth-quakes in the distant past, there had been atleast 17 large earthquakes with M 7.0 withinthe territory of Myanmar in the past 170 years(Thein and Swe, 2008). Some recorded largehistorical earthquakes are listed in Table 1(Myint and Swe, 2006).

c© 2010 Department of Geological Engineering, Gadjah Mada University 145

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Table 1: List of some strong earthquakes in Myanmar

146 c© 2010 Department of Geological Engineering, Gadjah Mada University


Figure 1: Seismotectonic map of Myanmar re-gion

Earthquake related hazards

Building collapse is a major hazard. The severedamages of the large magnitude earthquakesmight affect mostly on the rural house sincethey are unengineered structures, even in thecity where the old buildings existed. The popu-lation density tremendously increases in majorcities; unfortunately, these large cities lie near orquite close to the major active faults in Myan-mar (for an instance, the cities of Yangon, Bago,Taungoo, Napyitaw, Pyinmana, Kyaukse, Man-dalay, and Myitkyina stand along the SagaingFault and Taunggyi City is near the KyaukkyanFault). At least ten million people are livingon the Sagaing Fault region. Liquefaction is acollateral effect of large earthquakes that hap-pened in the younger alluvial deposits consist-ing of loose silty and sandy soil. Past experi-ences from the Tagaung Earthquake (M 7.1, 5Jan, 1991) and the Taungdwingyi Earthquake(M6.8, 22 Sep 2003) (Figures 2 and 3) indicatedthat many rural houses were sinking down tothe earth, the foundations of the ancient stupas

Figure 2: Collapse of primary school at Cheze-aing village during Taungdwingyi earthquake

Figure 3: Settlement of school foundation dueto liquefaction

were tilted and many paddy fields were dam-aged by sand boiling. Many cities in the cen-tral part of Myanmar are situated on the allu-vial plain which are highly vurnerable to lique-faction when large magnitude earthquake hap-pens.

Tsunami causes and characteristics in Myan-mar

There were also records of moderate tsunamigenerated by two large magnitude earthquakeswhich originated in the Andaman-Nicobar Is-lands. These are the M 7.9 Car Nicobar Earth-quake (31 December 1881) and the M 7.7 An-daman Island Earthquake (26 June 1941). Thetsunami generated by the giant 2004 Suma-tra Earthquake also caused moderate damage(Figures 4 and 5) in the delta region and thesouthern Myanmar Coast. The causality is alsocomparatively lower than the other countriesaround the Indian Ocean (Table 2). Thus, it


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Figure 4: Record of damage and casualties in2004 Tsunami at the Ayeyarwady Delta Region

Figure 5: Record of damage and casulities in2004 Tsunami at the Ayeyarwady Delta Region

is evident that Myanmar is vulnerable to haz-ards from moderate and large tsunamis alongits long coastline. In view of these, it is neces-sary to assess the earthquake and tsunami haz-ard potential along the Myanmar coastal area.

After 2004 Tsunami, scientists from Geolog-ical Survey of Japan could find at least threelarge tsunami records in the Bay of Bengal andAdman Sea region during 2800 years time span.The last one before 2004 was dated as of 550 to700 years ago (Jankaew et al., 2008), after study-ing peaty soil in the sand sheets of Phra Thong,125 km north of Phuket, Thailand. Therefore itcan be assumed that big tsunami might occur inabout 500 to 700 years.

Again, Chandra (1978) (in Satyabala, 2003)located the epicenter of 1762 earthquake at 22N and 88 E, i.e., north of Kolkata. On theother hand, Ganse and Nelson (1982) locatedthe epicenter at 22 N and 92 E, i.e. east of Chit-tagong where the damage was severe. In caseof the epicenter was on the land, the possibil-ity of tsunami is very less. Considering the twodifferent views on the epicenter of 1762 Earth-quake, it is difficult to ascertain whether theEarthquake generated tsunami or not.

Recent paleoseismological studies by thejoint Myanmar-Japanese teams in the northernRakhine Coast (Aung et al., 2008) revealed thepresence of at least three raised marine terraceswith radioactive carbon dates result rangingfrom 1400 BC to 1860 AD, and indicate thatthere were at least three great earthquakes (in-cluding 1762 earthquake) in that region in thepast 3400 years.

Landslide causes and characteristics in Myan-mar

Geomorphologically, Myanmar has two moun-tainous provinces: namely the Western Rangesand the Eastern Highland. These provinceshave inherently unstable nature among the ar-eas of the country. The steep slopes, unstablegeology, and intense monsoon rains combine tomake the mountainous regions one of the mosthazard-prone areas in Myanmar. More recentlythere has been an increase in human settlementof hazard-prone areas as a result of populationpressure, as well as improvement in accessibil-ity by road and the onset of other infrastructuredevelopments. Consequently, natural and man-made disasters are on the increase and eachevent affects people more than before. Besides,the major river of Myanmar, River Ayeyarwadyflows from North to South in the central low-land. Because of the flooding and erosion, thelandslides occur along the banks of this riverand its distributaries.

Due to the rising of groundwater in mon-soon, the saturation of the soil increases hencedestroys the capillary tension in soil and re-duces its cohesion. This process leads to highpore water pressure in slopes. Again due tothe troublesome materials in slopes, liquefac-



Table 2: Official damage and deaths for Myanmar in 2004 tsunami

tion, expansive nature, subsidence and sensi-tive phenomena occur in mountainous regionsof Myanmar. Soil erosion is another problemwhich is exaggerated with heavy rain fall anddeforestation. The uncontrolled flow of rainwa-ter on slope surface washes out soil and boul-ders and threaten the people living along thebase of the hilly regions in Myanmar. Becauseof the rapid urban development and increas-ing the traffic flow, mass scale construction ofhouses and heavy structures on entire hill maycause landslides.

Soluble rocks with solution cavity (Figure 6)in Karst areas also cause planar sliding and sub-sidence. Earthquakes have acted as triggers tomany landslides and ground failures in someparts of earthquake-prone areas such as in Pyi-noolwin area, Tagaung area and Taungdwingyiarea.

Various sizes of landslides frequently occurin mountainous regions of the Western Ranges(Figure 7) and some localities in the EasternHighland, especially along the western flank ofthe Tanintharyi Ranges. The collapses of riverbank are found along the Ayeyarwady Riverand its distributaries. The Western Rangeshas experienced many types of landslides andearth movement, i.e. rock falls, rock slides, soilavalanche and mud flows of various scaled dueto the wedge failure, plane failure, toppling,and circular failure. The direct impact of land-slide in this region is the damage of the infras-

Figure 6: Karst Formation Near PwekaukChaung in Eastern High Land

tructure rather than human settlement becausethese areas are sparsely populated (Lain 1983).

In the Eastern High Ranges, landslides of alltypes were occurred along the western flank ofthe Kachin, Shan and Tanintharyi Ranges. InTanintharyi area, some rural houses and pri-mary school were buried in the debris materialsduring the rainy season in 1999.

In 2001, subsidence events were occurred inNansang area due to the Karst formation. Anyimpacts were not observed due to these events.However, landslides in Mogok have been ob-served as some types of mass movements andcaused the loss of lives and properties in June,2008. Some historical landslides events are


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Table 3: List of some landslide events in Myanmar

Figure 7: Multi-landslide scars occurred inWestern Ranges

shown in Table 3 according to their character-istics.

3 Analysis of the Results of the Research

3.1 Earthquake hazard potential areas inMyanmar

According to the facts mentioned above, theSeismic Zone Map of Myanmar has been devel-oped in 2006 (Thein and Swe, 2006). As shownin Seismic Zone Map (Figure 8), five seismiczones are demarcated and named (from low tohigh), mainly following the nomenclature of theEuropean Macroseismic Scale 1992.

3.2 Tsunami hazard locations in the country

Myanmar has a fairly long coastline of approxi-mately 2,200 kilometers long. It consists of threemain segments; namely, the Rakhine Coast inthe northwest, the Ayeyawady Delta in themiddle, and the Taninthayi Coast in the south.

The northern Rakhine Coast, adjacent toBangladesh, consists of some large offshore is-lands, and the intervening areas between theseand the coastline are marshy and partly cov-ered with mangrove forests. This setting there-fore provides partial protection from tsunamiwaves. However, the southern Rakhine Coast



Figure 8: Seismic zone Map of Myanmar earth-quakes on the known segments of the activefaults and basement geology, three seismicallyactive regions can be identified in Myanmar: (1)the northwestern region (part of the WFB); (2)the central lowland; and (3) the Shan Plateau-Yunnan Region.

generally is rocky and sandy with three popu-lar resort areas. Thus, this part is comparativelymore vulnerable to the tsunami hazard.

The Ayeyawady Delta is a large delta withwetlands and mangrove forests, thus provid-ing partial protection from tsunami waves. Thedelta front is wide with shoals in some places,thus slowing down the tsunami speed. Imme-diately to the east lies the mouth of SittoungRiver which is a wide estuary that widenssouthwards to form the Gulf of Mottama.

The Taninthayi Coast consists of two geo-morphic parts. The northern part is rocky andbare, but the southern part contains the Myeik(Mergui) Archipelago that consists of morethan eight hundred islands which are sparselypopulated, with human settlements mainlyon the east coasts, i. e., in the shadow sidesfrom tsunami waves. Moreover, the southernpart is partially covered with mangrove forests,thus providing partial protection from tsunamiwaves. These factors indicate that the south-ern part is comparatively less vulnerable to thetsunami hazard.

With the reference to the seismic zone mapand certain characteristics of the three seg-ments of Myanmar coastline mentioned above,the probable earthquake and tsunami hazardsalong the Myanmar costal areas are summa-rized in Table 4.

3.3 Landslide potential areas in the country

Various sizes of landslides had frequently oc-curred in mountainous regions of Myanmar es-pecially in the Western Ranges and some lo-calities in the Eastern Highland. The WesternRanges has experienced all types of landslideand earth movement, i. e., rock falls, rock slides,soil avalanche and mud flows of various scaled.The direct impact of landslide in this region isthe damage of the infrastructure rather than hu-man settlement because these areas are sparselypopulated. In September 2004 in the middleof rainy season, there was a large scale land-slide (and earth movement) happened alongthe Kale-Kalewa road near to the Kale City,the Sagaing Division of Myanmar. Bridges andmain road of about 30 kilometers long were de-stroyed. Even a minor rock and soil slides can


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Table 4: Probably earthquake and tsunami hazard along the Myanmar coastal areas

Figure 9: Landslide found in Chaungkyin area

clog the road and it can take several hours to re-move. Figures 9 and 10 show some record pho-tographs of the Kale landslide in 2004.

One of the major rivers of Myanmar, RiverAyeyarwady flows from North to South in thecentral low land. Because of erosion and flood-ing of the river, landslide hazards occur alongthe bank of this river and its distributaries.

4 Discussion on Geo-disaster MitigationMeasures in Myanmar

On the purpose of Protecting Life from Geo-Disasters, the Seismic Zone Map of Myanmar(2005) was prepared by a team led by Dr.Maung Thein during 2003 to 2005 with severaldetail observations and brainstorming. Tec-tonic activities in connection with earthquakeinformation from external sources are applied

Figure 10: Serious landslides and rock- fallsalong Kale-Kalewa main road



in the development of the map (Maung Theinand Tint Lwin Swe, 2006), deterministically andsome intuitively.

During the years of 2005 to 2007, the Myan-mar Geosciences Society, in collaboration withthe Myanmar Earthquake Committee (MEC),sponsored some graduate students of the Uni-versities of Yangon, for the preparation of pre-liminary seismic micro zoning maps for fourseismically hazardous cities. These are deter-ministic maps.

In the development of Building Code (Myintet al., 2007), the study of that of the other coun-tries like Thailand, India, Indonesia and theUBC (Uniform Building Code of United States)are very helpful, but the background geologicalsetting as well as the surface composition of ge-ologic material, especially technical characteris-tics and distribution of rock and soil deposits ofMyanmar, is quite different from that of othercountries. For earthquake safety of buildings,seismic demand from various sources shouldbe analyzed by means of ground motion atten-uation models and used as a seismic coefficientwhich is then applied in calculating base shearof the structure. Earthquake ground motionand intensity levels can be obtained from theproper installation of network of the seismolog-ical stations covering well defined seismogenicsources.

However, the number of seismological sta-tions in Myanmar is limited for acquiring earth-quake information and establishing databaseand need to be upgraded not only instrumen-tation but also in technical concerns.

For application of seismic design code, lev-els of earthquake intensities are mainly basedon the earthquake-zoning map. During the de-velopment of building code in Myanmar, therequirement of modern seismological instru-mentation and technical improvement in thefield of engineering seismology and earthquakeengineering shall be enhanced by cooperativeworks among the scientists and engines fromvarious organizations.

Education of non-technical people aboutearthquake and its related disasters is nowbeing started by the collaboration of Depart-ment of Meteorology and Hydrology (DMH),

Relief and Resettlement Department (RRD),Myanmar Engineering Society (MES), Myan-mar Geosciences Society (MGS), Asian DisasterPreparedness Centre (ADPC) and Universitiesin Yangon.

Taking consideration upon the paleoseismo-logical finding in northern Rakhine Costal Areaand Bay of Bengal, the probable earthquakesand tsunami hazards along Myanmar costal ar-eas, has been prepared by the members of MECand this map is going to be established soon.

To mitigate the landslide hazards, local com-munity plays an important role. Therefore, ed-ucation of landslide for rural areas has been ini-tiated by the collaboration of Ministry of Edu-cation, MES, MGS and ADPC.

To control slope stability, some technicalmethods such as excavation method, watermanagement and drainage measure, struc-tural support measure (rock-bolts, rock-anchor,retaining wall, and buttress), geotextile andriver training measure are applied in Myanmar.Landslide potential map is also being prepared.

5 Conclusion

As Myanmar is an earthquake prone coun-try, it has two important tectonic features andearthquake sources, one within Myanmar andthe other in her neighbourhood to the West.These are the active Sagaing fault, trendingNorth-South across the entire length of centralMyanmar, and the Sunda subduction megath-rust zone running through off-shore Southwestand West of the Myanmar coast and on-landto the West and Northwest of Myanmar. TheSagaing fault passes through the most pop-ulated areas of Myanmar where large citieshave been built. Therefore, active fault studieswith characterization of earthquake responsespectrum on engineering structures and designcode for buildings ; upgrading of the exist-ing seismological stations; and then installationof some more modern-type seismological sta-tions in some suitable locations, such as Hpa-an, Pathein, Bago, Pyinmana, Magway, Kale-myo and Muse are necessary.

Concerning tsunami hazard, the intensity interms of run-up and the extent of the inunda-


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tion was comparatively lower than the othercountries around the Indian Ocean and thecausality and damage was also lesser. For dis-tance tsunami source (like Sumatra), Myanmarcoastal areas have more time for preparation toescape from the killer waves. The records from2004 Indian Ocean Tsunami show that the firstarrival of the tsunami was at least three hourslater than the time of earthquake happened.But for the near source tsunami (for instance, alarge earthquake happened in the Andaman Is-land region and if it generates the tsunami), thedelta region of Myanmar has only short dura-tion for preparation. Therefore, it is prudent toinstall an effective tsunami warning system inthe northern Bay of Bengal with internationalcooperation.

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