Introduction

 In the increasingly competitive global economy, Science and Technology have become strategically more important in national development.  The rapid advancements and the pervasive role of S & T in the global economy necessitate the nation to build up and enhance its capability in Science and Technology to take advantage of potential wealth creating opportunities.  In view of the above, a thrust should be made to harness S & T as key drivers in raising the national capacity to acquire and utilize knowledge in Science and Technology to foster innovations.

 Successive governments in Sri Lanka have been involved in developing a consistent Science and Technology policy.  Comprehensive statements were drawn up by a Presidential Task Force in early 1990’s, the Natural Resources Energy and Science Authority (NARESA) in 1995, and the National Science & Technology Commission (NASTEC) in 2002 and thereafter.  The present document is a distillation of the foregoing policy statements and of the new thinking that has occurred in response to the rapid advances and changes in global Science and Technology, as well as the social, political and economical developments in Sri Lanka.

 The proposed National Science and Technology Policy elements and strategies are expected to be the basis for the attainment of a scientifically and technologically advanced society and for a holistic approach to strengthen and develop Science and Technology.  The policy goals also emphasize on capacity building and strengthening of Science and Technology through intensification of advancement and dissemination as well as the application of knowledge and technologies in particular, the leading–edge technologies.   

 These policy elements constitute an overarching statement that provides a framework for more specific policies and implementation plans.  They have been designed keeping in mind the social and material well being of the people of the country, protection of the environment and the need for sustainable growth and development.  It is envisaged that the National Science and Technology Policy when adopted, will provide a consistent, long-term framework for growth and development in Science and Technology of the country, leading to the achievement of the status of a developed nation in the foreseeable future.

 Policy Elements

 1.     Foster a national science and innovation culture that effectively reaches every citizen of the country by:    

a)       Providing  equal  and  adequate  opportunities  for  all  to  acquire  a  basic education in  science  and  its  practical  applications

b)       Encouraging  a  questioning  mind  and  the  application  of  scientific  methodologies in  every  day  life for efficiency and productivity

c)       Cultivating among  all Sri Lankans, an  appreciation  of  the  values and ethics   of science  and  technology  and  related research, leading to entrepreneurship as  an essential  aspect  of  modern society

d)       Promoting public awareness of S & T

 2.     Build  up,  sustain,  and  progressively  increase  the  resource  base  of  scientists and  technologists  necessary  to  respond  to  the  developmental needs  of  the country  by:    

a)       Improving  the  working  and  living  conditions  of  the  scientists  and technologists

b)       Providing  incentives  for research and innovation that  would  help  to  retain  recognized  high  calibre scientists and  technologists in Sri Lanka and  attract  the Sri Lankan expatriate scientists to contribute to national development

c)     Training scientists and technologists in advanced technologies and knowledge management to support local industries and other needs of the country

3.     Recognize  the  key  role  of  science  and  technology  as  an  important  and  essential  item  in  national  development  by:    

a)       Establishing  an  Inter-Ministerial  Task Force   chaired  by  the President  

b)       Including  scientists  and  technologists  in  the  formulation  of  policies  and plans, and  decision-making  at  the  highest  levels

c)       Integrating scientific  and  technological  planning  into  the  ministerial,  provincial and  national  level  plans  of  the  country

d)       Involving scientists and technologists in monitoring and  reviewing strategies, legislation,  and  institutional  framework  for  science  and technology  in  all relevant  sectors

 4.     Foster  scientific  and  technological  activities  in  priority areas  and  encourage  the  development  of  self-reliance  in  scientific  and  technological  capability  by:    

a)       Progressively  increasing  the public and private sector investment  in  science  and technology  (up  to  1.5 %  of GDP,   by the year 2016)

b)       Developing and  strengthening the existing S & T institutions and universities  to generate high quality research and train scientists

c)       Establishing where  appropriate,  new  centres  of  science  and  technology  in the high  priority  areas  where advanced international level research facilities are available

d)       Improving  the  autonomy  and  flexibility  of  science  and  technology institutions

e)       Promoting  partnerships  among  industries,  research  institutes  and  universities for knowledge generation through research

f)     Promoting  and expanding public-private  partnerships  in  science  and  technology activities and encouraging investment in R & D 

 5.     Develop,  select,  acquire,  and  adapt  scientific  knowledge  and  technology  necessary  for  the  progressive  modernization  of  all  sectors  so  as  to  enhance  the  country’s  competitiveness  in  the  world  economy  by :

a)       Encouraging multi-disciplinary  development research

b)       Up- scaling  of research based  new  processes  and  technologies to pilot and commercial scales  with state support

c)       Encouraging industries  and  R & D institutions  to  give greater  emphasis  to technology transfer  and  technology  adaptation 

d)       Development  of  technologies  suitable  for  transferring  to  small  and  medium enterprises,  particularly  enterprises  at  the  village  level through collaboration between R & D institutions and the SME sector

  6.     Ensure quality standards of  S & T institutions, S & T products and services to face the challenges of competitive global markets and needs of the domestic market by :    

a)       Implementing effective, science based, transparent monitoring and reviewing systems for S & T institutions and taking corrective steps to ensure quality

b)       Ensuring the effectiveness of activities  of  the   institutions  mandated to  maintain international quality  standards  of  institutions,  services  and  management  systems such as ISO 9001, ISO 14000, ISO 22000 etc. and certification of product  quality  through  their own certification  schemes with the application of appropriate S & T  

c)       Ensuring the effectiveness of activities of the  relevant  accrediting  bodies  for  laboratory accreditation against international standards such as ISO 17025 etc.

d)       Ensuring the effectiveness of accreditation activities for conformity assessment in supporting Quality Assurance

 7.     Ensure  sustainable  development  while  conserving  the  natural  resources  of  the  country  and  protecting  the  environment,  through  the  appropriate  use  of  Science  and  Technology  by:    

a)       Promoting the  acquisition,  transfer,  and  development  of  clean  technologies  in industry through application of S & T

b)       Strengthening and  implementing  laws  and  regulations  to  protect  the environment

c)       Formulating transparent policies governing the use of   natural resources such as soil and water to   meet the long- term needs  of  the  country

d)       Establishment of monitoring and evaluation systems for the successful implementation of the above. 

Understanding Earthquakes and Tsunamis

Dhammika A. Tantrigoda,

Dept. of Physics, University of Sri Jayewardenepura,

Gangodawila, Nugegoda

 Introduction

Dreadful memories of the tsunami that ravaged several coastal cities of Sri Lanka claiming many innocent lives on the early hours of 26 December 2004 is still haunting the minds of many of us. This powerful tsunami, which devastated several South Asian countries, originated off the west coast of Sumatra. According to local and international news agencies, the tsunami has claimed well over 150 000 lives causing unprecedented damage to property. It has been generated as result of a massive Earthquake of magnitude 9 on the Richter scale. According to the United States Geological Survey, this is the fourth largest earthquake in recorded history, the largest being the great Chilean Earthquake that took place in 1960, with a magnitude of 9.5 on the Richter scale.

Tsunami is a train of sea waves triggered off due to a sudden collapse of the ocean floor. This normally happens as a result of earthquakes taking place at shallow depths below the sea floor. Tsunamis can also be caused by volcanic eruptions and falling of large boulders into the water. Violent eruption of Krakatoa volcano in 1883 caused sudden collapse of the sea floor leading to a massive tsunami, which claimed a large number of human lives. Tsunamis are sometimes referred to as tidal waves. This is a misnomer, as tsunamis have nothing to do with tides that are caused by the gravitational attraction of the sun, moon and other planetary bodies.  The word tsu-nami has a Japanese origin and it means harbour wave (“tsu” means harbour while “nami” means wave). Tsunamis have enhanced effects in harbours and other U or V shaped water inlets and this could have been contributed towards the Japanese origin of the word.

 Origin of Earthquakes

 Let us now see how earthquakes that trigger tsunamis are originated. The thin outermost part of the earth (first 50 to 100 km) is known as the lithosphere and it consists of several large detached tile like segments and several other such smaller segments. These segments are known as lithospheric plates or simply plates. Plates “float” on a region called asthenosphere, which consists of rocks that have transformed into an extremely “thick” or viscous material, which can flow with very slow speeds. All the plates are moving relative to each other at very slow speeds in a complicated manner. Earthquakes can be observed in most plate margins, especially at the vicinity of plate margins known as transform faults and subduction zones. At a transform fault two plates move passing each other horizontally. One such plate margin is in California in western USA. This is known as San Andreas Fault and many powerful earthquakes have been generated at this fault.  At a subduction zone a heavy oceanic plate goes under a relatively light continental plate (figure 1). Descending oceanic plate tries to drag along some of the adjacent continental plate resulting strains in both plates. So the subduction does not proceed smoothly and continuously; it proceeds with jerks and each jerk is responsible for an earthquake. The oceanic plate on which most of the Indian Ocean is lying on is plunging down (subduct) under Indonesia and the recently observed magnitude 9 earthquake took place at this plate boundary.

 

 

figure 1

 

Trigger Mechanism

 No one exactly knows the mechanism that triggers earthquakes as they happen deep down in the earth. However, we can build models to explain how earthquakes occur in just as we build models to explain atomic and nuclear phenomena.  The elastic rebound model is one such model that has been built to explain the origin of earthquakes that takes place at a transform fault. It is useful to study this model as it gives a very good insight into how earthquakes originate.  As discussed earlier, at a transform fault two plates move passing each other almost horizontally. Due to frictional and other forces each plate is trying to stop the motion of the other that result in deforming both plates. This is somewhat similar to two gigantic rubbers glued to each other trying to move in opposite directions parallel to the two faces that have been glued. As a result of relative motion of the parts of the rubbers that are away from the glued boundary they get deformed and are in a state of strain. The figure 2.b shows the way in which two plates can undergo deformation in this manner. There is a limit to which “glued” rocks can withstand deformation and once this limit is passed, rocks in that region snap releasing huge amounts of energy. This is how the elastic rebound model explains the origin of an earthquake. Normally the whole boundary of “glued” plates does not get dislocated in one instance. Only the rocks in a certain region of the boundary get dislocated and this has been illustrated in figure 2c. If the extent of the dislocation is large the release of elastic energy is also large and the earthquake is classified as one having higher magnitude. Once the main shock occurs, other parts of the glued regions can also snap and release energy and these events are known as after shocks. This explains how several small earthquakes that were reported to have taken place at the same plate boundary occurred after the massive earthquake of 26^th December. After shocks are normally not powerful as the main shock. Sometimes a small release of energy can take place before the main shock known as foreshocks. Dislocation of rock units over an extensive region on the plate will take place in an earthquake. However, compared to the size of the whole plate boundary this region can be well approximated to single point. This point is known as the focus of the earthquake. The point directly above the focus on the surface of the earth is known as the epicentre of the earthquake.

  

figure 2

 When an earthquake takes place basically two types of waves collectively known as “body waves” transmit the energy outwards. Once these waves reach the surface their interference with each other and other phenomena will lead to the formation of another type of waves known as “surface waves”. Unlike body waves surface waves have higher amplitudes and almost all the physical damage due to an earthquake is due to the effects of surface waves. How the body waves and surface waves are generated and how they travel and also how the whole earth vibrates like a giant bell after an earthquake is a fascinating problem in physics and in applied mathematics. Some of the concepts in physics and mathematical tools developed to solve this problem have been successfully used in formulating some of the concepts in advanced branches of contemporary physics such as quantum mechanics and nuclear physics.

 Richter Scale Magnitude of Earthquakes

 Normally we would like to represent the magnitude or intensity of any process using a numerical value of a certain property related to the process on a suitable scale. For example, intensity of rainfall is expressed using height of the water collected in an open vessel kept in the rain (rain gauge) using a millimetre scale. Similarly the magnitude of an earthquake is expressed in terms of the amplitude of the ground motion. The scale on which this is expressed is called the Richter scale. In the original Richter scale, Richter defined the magnitude in terms of the maximum trace amplitude on a standard seismometer, sensitive equipment capable of monitoring vibrations of the earth, stationed at a distance of 100 km from the epicentre of the earthquake. The amplitude is expressed on a logarithmic scale. According to this scale an earthquake that shows amplitude of one metre on the standard seismometer has a magnitude 6. An earthquake that shows 1 km amplitude is designated to have a magnitude of 9 on this scale. There are practical problems in using this scale especially due to non-availability of seismic stations at an epicentral distance of 100 km of each and every earthquake. Therefore the original concept of Richter has been modified and new formula has been suggested. The new formula is capable of computing the magnitude of an earthquake monitored at any seismic station on the globe.

 Energy Release

Methods of estimation of total energy released in an earthquake have been given by Richter, Guternburg and many others. It is somewhat difficult to appreciate the amount of energy released in an earthquake from the numerical magnitude alone. Comparison with other known processes that release energy would be of some help in this regard. A magnitude 1 earthquake is so weak that they can only be observed with sensitive instruments. Kinetic energy associated with such an earthquake is more or less equal to the kinetic energy of a vehicle weighing 15000 kg travelling at a speed of 130 km per hour. One ton of the explosive trinitrotoluene (TNT) releases about 4.2x10⁹ (four thousand two hundred million) of Joules of energy. Energy released in the atomic bomb, which destroyed Hiroshima, is the same as that released by an explosion of eleven kilotons of TNT. This is equivalent to the energy released in a magnitude 5 earthquake. An earthquake of magnitude 9 releases about 1.6 x 10¹⁸ Joules. All lesser earthquakes numbering more than 500 000 per year only releases five per cent of the energy released by a magnitude 9 earthquake.

 

Generation of Tsunamis

 When a very large earthquake occurs at a subduction zone, dislocation of the deformed and strained rock units cause the ocean bottom above the focus to rupture and collapse. This may result in either vertical upward or downward movement of the sea floor of an extensive region. Disturbed water mass will soon try to regain the equilibrium under gravity and in the process a train of waves are generated. This is somewhat analogous to a plucked string of a musical instrument trying to regain equilibrium by undergoing vibrations. The manner in which a disturbance caused by collapsing of sea floor generates a train of sea waves and the calculation of properties of the waves so generated can be carried out using classical fluid dynamics. The discussion, which follows, is based on qualitative treatment of the results obtained from such calculations.

 Basics of Wave Propagation

 We are all familiar with tiny water waves or ripples generated on the surface of a clear and calm pond as a result of dropping a pebble. We see that even though the ripples move outwards from the point at which pebble was dropped, small pieces of leaves floating on the water do not travel with the wave. Instead they oscillate up and down and to and fro around a fixed position. This clearly indicates that the medium (ie. water) does not travel when a wave is propagated through the medium. But the wave gives the capability to a piece of leaf to oscillate and this indicates what is been propagated is only the energy.   In a wave we observe the repetition of a certain fundamental shape (figure 3). Length of this fundamental shape is known as the wavelength, speed at which this shape travels through the medium is called the wave speed and the time taken by the fundamental shape to travel its own distance is called the period of the wave. It is interesting to see how water particles (the medium) oscillate when a water wave is propagated. Contrary to what is stated in many elementary physics textbooks including those we use in our own schools, oscillations of water waves are not confined to the vertical direction.  If the oscillations are confined to the vertical direction, then water should have stretched vertically at crests and compressed at troughs of the wave. We know very well that water does not have sufficient elastic properties to sustain such deformations. Therefore when a crest is formed water from the neighbouring region will flow in the horizontal direction to compensate for the amount of water that has gone up resulting in a trough in that region. So the oscillations are taking place in the vertical as well as horizontal directions. Very often horizontal component is more pronounced compared to the vertical component.

figure 3

 

Speed of Tsunami Waves     

 A sudden vertical disturbance of a water column generates a very large number of waves (pulses to be precise) with different wavelengths and they normally travel with different speeds and have different periods.  All the waves that have wavelengths greater than six times the depths of the water layer travels with the same speed. This speed is equal to the square root of the product of acceleration due to gravity and the depth.  According to this formula tsunami waves travelling in region of 4 km water depth has a speed of 200 meters per second or 720 km per hour. This value is comparable with the speed of a commercial jet aircraft. When tsunami waves reach the edge of the continental shelf their velocity reduces to about 45 metres per second and further reduces to about 10 metres per second when reaches the show.  As a result of progressive reduction of speed when climbing the continental shelf tsunami waves acquire large amplitudes. Lower speed in the front part and higher speed in the rear part of the wave will result in bunching up water over a narrow region forming a tall wall of water near the shore.

 Energy Propagation

 Tsunamis are quite different to the water waves generated by the wind that we are very much familiar with. Tsunami waves have very long wavelengths, which are generally of the order 100 km to 200 km where as the wavelengths of waves generated by winds rarely exceeds a few tens of metres. In waves generated by winds the surface of the water mostly takes part in oscillations and the energy of the wave is almost limited to the surface. In tsunami waves the whole water column from the surface to the bottom of the sea takes part in oscillations and the energy is distributed in the whole water column. When it is passing through a region of the deep ocean its amplitude becomes very small as the total energy of the wave is now shared by a water column, which may be five to six kilometres deep.  This is the reason as to why in the deep ocean tsunamis have amplitudes of less than one metre and are not detected by ships passing by. When a tsunami reaches a region of shallow water its energy is distributed in a small column of water and therefore should have higher amplitude to have the same amount of energy it had when passing through a deep region (tsunami waves loose very little energy when travelling through the deep ocean).

 Main Phases of Tsunami Waves

 Physicists and mathematicians have extensively studied water waves including tsunamis. It has been shown that a tsunami wave has two main phases in general as shown in figure 4. First phase is part of the wave in-between A and B in Figure 4 and this is known as Jeffery phase, in memory of one of the mathematicians who contributed to the better understanding of propagation of tsunamis. Rest of the wave is known as the oscillatory phase. It is useful to note that the Jeffery phase is only a sort of a crest of a wave and it does not have a trough.  Actual size of the Jeffery phase depends on the nature of the initial disturbance of the water caused by the collapse of the sea floor.

figure 4

 It has been reported that mainly two destructive waves struck most coastal towns   of Sri Lanka on the last 26^th   of   December. There has been a spectacular recession of the sea exposing the sea floor to a distance of about 1 km from the shore in many places during the time interval between the two waves.  It may be interpreted that the Jeffery phase with reduced amplitude may be responsible for the initial wave, which was not very strong. The Jeffery phase will be followed by the first trough of the oscillatory phase, which is responsible for the recession of the sea. As explained earlier a trough of water waves are formed as a result of horizontal movements of the water towards the crests and this further explains complete depletion of water exposing the sea floor.   Then the first crest of the oscillatory phase will come with enhanced amplitude and most of the devastation will be caused by this stronger second wave. It is possible for several other waves also to come, but their severity would depend on several other factors.

 Alteration of Direction and Penetrating into Shadow Areas 

 When a wave undergoes change in velocity it normally suffers a change in its direction of propagation. This phenomenon is known as refraction. Tsunami waves also can undergo refraction as a result of change in velocity due to the change in depth of the water column in which they are travelling. Sharp variation of the topography of the sea floor due to the presence of oceanic ridges and   massive seamounts are capable of guiding the direction of tsunamis in this manner. Capability of a wave front to bend at an obstacle and reach areas covered by the obstacle is known as diffraction. Any wave type has this capability and the extent to which it can penetrate into the covered area is limited to a distance of the order one wavelength. This phenomenon may responsible for the tsunami waves that originated near Sumatra, which faces the eastern coast of Sri Lanka to reach its western coast. As the wavelength of the tsunami is of the order of 200 km it can easily affect the western coast even upto Negumbo due to the diffraction phenomena.

In the recent tsunami we noticed that Maldives, which is an oceanic atoll, is comparatively less affected in spite of its seemingly vulnerable position in the Indian Ocean. The safeguards available to atoll dwellers are twofold. First of all the atoll isles rise steeply from the sea floor like pinnacles and there is no desirable topography of the sea floor for the wave to enhance its amplitude. Further, most of the isles have dimensions less than the wavelength of tsunami waves and therefore the waves will pass the isles almost “unnoticed”. 

 Tsunami Warning System and Public Awareness Programme

After the tragic events of December 26^th many professionals and several others have urged the government to consider the possibility of having an early tsunami warning system in Sri Lanka. There is such a system that covers most countries in the Pacific Basin, Hawaii islands and other US regions bordering the Pacific Ocean.  Basically a tsunami warning system is an international network of seismometers (or seismic observatories) and “tide stations” installed in relevant countries and relevant sea areas. These instruments are connected to a central station via satellite. The central station may also have access to other international seismic networks such as the one owned by the United States Geological Survey.  Seismometer network will indicate occurrence of earthquakes in the region covered by the network and the geophysicists in the central station will compute the location and the magnitude of the earthquake. If the earthquake has taken place in a vulnerable sea area and if its magnitude is reasonably high (more than 7 on the Richter scale) they can examine readings of the tide gauges in the vicinity of the focus of the earthquake to see any signs of the formation of a tsunami. Warning bulletins will then be issued to the member countries if the necessity arises.

 A tsunami warning system cannot be established by a single country. Several countries in a region, which are likely to be threatened by this natural disaster, will have to work together in establishing such a system. Therefore there are practical difficulties in establishing an early tsunami warning system immediately. Until such time we establish a suitable early warning system we may think of having our own improvised warning system. This system may consist of a small group of scientifically oriented dedicated people who work around the clock in a central station. They should examine seismic records at Pallekele and other stations or which we have access and compute the location and magnitude of any earthquake recorded. These computations do not require much advanced knowledge of seismology. Any person with reasonably good background of physics and mathematics and some exposure to computing can be easily trained for this purpose. They can also be on alert for news reports coming from neighbouring countries and warning bulletins issued by already established tsunami early warning centres and any other relevant information appearing on the internet. If a centre of this nature is available any outside agency that would like to warn us regarding an impending disaster can direct such warnings to this centre.

Sri Lanka has been generally considered a safe country with regard to natural disasters. Droughts and floods are the most frequently heard natural disasters. Sometimes heavy rains are reported to have triggered off landslides especially in the upcountry. Earthquakes of magnitude of the order of 5 or less on the Richter scale have been felt occasionally only arousing academic interest. Articles in the press by the experts often appear to reassure the safety of Sri Lanka soon after such events.  Popular belief among many of us was that there is no need to worry about earthquakes and tsunamis, as they are not “destined” to occur in Sri Lanka. This false sense security that has been developed over the years has contributed much towards our ignorance with regard to extreme natural disasters.  Our failure to realise the possibility of having a tsunami after a submarine earthquake exceeding magnitude eight on the Richter scale off the coast of Sumatra explains the extent of our ignorance regarding these matters.  Had the general public being knowledgeable about recession of the sea immediately prior to the arrival of the major tsunami wave they would have gone to safe places resisting the natural tendency to take advantage of once in a life time opportunity of exploring the exposed sea floor. All these are sad and grim reminders of our ignorance about natural disasters. The importance of having a comprehensive long-term programme to educate the general public with regard to such disasters has become an urgent need of the country. Earthquakes and tsunamis should occupy a centre place of this educational programme. Different aspects of natural disasters including scientific as well as sociological aspects should come into our education system at different levels starting from he junior school to postgraduate level in the universities.  Scientists will have the arduous task of understanding how these disasters originate and how they affect the different parts of the county and to draw up risk mitigation strategies. Finally through the media and education system of the country this knowledge should steadily permeate down to the general public. Intellectuals, educators and journalists of Sri Lanka have an enormous responsibility giving leadership to the initiation an effective awareness programme.

---

 

C. Special Publications

1. Impediments to Development of Science and Technology in Sri Lanka

? Proceedings of an NASSL Workshop on  held on 30 October 2004 at the Sri Lanka Foundation Institute, Colombo. Click on the arrow below to go to main page.

Ü

CONTENTS

(a) Introduction - Dr. U. Pethiyagoda

(b) Development of Science and Technology in South and South East Asia - A Comparative Review - Dr. K. A. de Alwis

(c) Politicians and Bureaucrats, Scientists and Technologists - Dr. W. W. D. Modder

(d) A Direction.... for Development - Dr. R. Wijewardene

(e) Discussion

---