Introduction
The tsunami of December 26 th 2004 was a natural disaster that occurred in the Indian Ocean. According to Shibayama (2005), the tsunami was caused by a 9.0 magnitude earthquake which released 23,000 Hiroshima-type atomic bombs in terms of energy.
The earthquake struck the coastal area off northern Sumatra in Indonesia triggering a gigantic tsunami that affected many countries including India, Maldives, Sri Lanka, Malaysia, Thailand, Indonesia and Africa. Being a region of soaring volcanic and earthquake activity, the eastern Indian Ocean basin experienced the tsunami that left many countries with devastating consequences.
According to Bappenas (2005) the impact of the tsunami was more devastating in the nations that border the Indian Ocean because such nations had no tsunami warning systems and timely communication.
According to Shibayama (2005), the tsunami attracted worldwide aid and effort from the United Nations, community groups, national institutions and international organizations because of the immense ecological, economic and social consequences experienced in Indonesia and the neighbouring countries.
According to Bappenas (2005), the Indonesian tsunami was the most devastating disaster as more than 250,000 people lost lives and 1.7million were displaced. This paper looks at consequences of this tsunami to the country of Indonesia in terms of general consequences, i.e. overview and physical mechanisms, physical consequences and socio-economic consequences.
Overview and Physical Mechanisms
Although tsunamis can originate from many geophysical mechanisms like volcanoes, landslides and earthquakes, the Indonesian tsunamis have been known to occur along the subduction zones and active seismic regions from tectonic earthquakes.
Latief et al. (2000) argue that there were 105 tsunamis in Indonesia from 1600-1999 most of which originated from tectonic earthquakes (90%) and a few from landslides and volcanic activity (10%). The areas prone to tsunamis on the Indonesian coast are:
The west coast of Sumatra, the south coast of Java, the north and south coasts of West Nusa, Tenggara and East Nusa Tenggara provinces, the islands of Maluku and North Maluku Provinces, the north coast of Papua and most of the Sulawesi coastline (2000, p. 28)
Prasetya et al. (2001) state that the Indonesian region is prone to earthquakes and tsunamis due to its location in an active seismic zone where the Caroline, Indo-Australian, Philippine and Eurasian plates converge. The joining of these plates results to a multifaceted area having a fault zone, subduction zone, back-arc thrusting zone, collision zone and back-arc spreading zone as shown in Figure 1.
Majority of the seismic active zones are found under the sea and they have been known to generate huge shallow earthquakes that lead to tsunamis (Silver et al. 2006). Historical records show that since 1900, about eighteen tsunamis have been produced in this region by such earthquakes with fourteen of the tsunamis occurring in eastern Indonesia (Prasetya et al.2001, p. 296-298).
This is an indication of an unstable seabed in the region that is able to produce tsunamis than other parts of Indonesia (p. 296-298).
Figure 1: Tectonic and tsunami map of Indonesian archipelago (Adapted from Silver et al. 2006)
Frequent tsunamis in Indonesia occur in the Makassar Strait, which forms a vital border between the western and eastern regions (Silver et al. 2006). Six of the recorded eighteen tsunamis since 1900 occurred in Makassar Strait from large shallow earthquakes formed through back-arc spreading.
These tsunamigenic earthquakes have epicentres near the western shore of Sulawesi Island and these epicentres are disseminated relative to two fault zones that traverse the Makassar Strait (Prasetya et al. 2001, p. 297). These are Palu-Koro fault zone which connects with Sulawesi subduction zone to the north and Paternoster fault to the south.
The 2004 tsunami was the most tragic event occurring in Indonesia from the Sumatra earthquake that generated a tsunami that not only affected Nangroe Aceh Darussalam (NAD) and north Sumatra provinces but also spread to nearby nations.
Nevertheless, Indonesia was the most affected region where the disaster killed many people and displaced others. According to Bappenas (2005), there was insufficient time for any alerts and evacuations hence causing a crisis.
Physical Impacts of the Disaster
The 2004 tsunami had significant geological effects on the Indian basin and destructive effects on communities living at the coastal region and its environs. Studies have shown that the tsunami greatly damaged fishing boats, houses, prawn culture ponds, tourist resorts, soils and crops as well as livelihoods of coastal communities.
Moreover, since most people preferred to live near the coast, such regions were usually highly populated which needs us to understand the impacts of this natural disaster (Saatcioglu et al. 2005, p. 80-3). This tsunami hit hard the offshore islands and the Sumatra coasts on the south and northern sides.
The west-facing coastlines of Sumatra were hit by waves exceeding 30 meters within a period of fifteen to thirty minutes of the earthquake (Richmond et al. 2006, p. 240-5). There were tsunami flow depths of above thirteen meters along a 135km stretch of the Northwestern coast that led to extensive damage and alteration of the coastal region (Moore et al.2006, p. 254).
Furthermore, there was extensive deposition of tsunami deposits composed mainly of sand in northern Sumatra from the zone of erosion near the shoreline to within twenty meters of flooded sites. According to Moore et al. (2006), the erosion zone width increased with the 2004 Indonesian tsunami height.
A survey of the physical impacts of the tsunami indicated that the highest shore sand deposits were about 1660 meters and five kilometres of mud deposit layers inland (p. 256).
According to Richmond et al. (2006), the tsunami deposit coverage depended on the limit of flooding, which was controlled by the slope of land and waves (p. 244-9). The different levels of deposits along the land led to irregular deposition of mass.
Generally, there was a thick deposit away from the shoreline to a place where it levelled at some point then became thin near the landward boundary. The changes in surface topography greatly influenced different levels of thickness of the sand sheets, especially with depressions that were in-filled and highs that lacked or had minimal deposits.
For example, areas with beach ridges had varied deposit thickness with high sand deposits of eighty centimetres far from the normal five to twenty (Moore et al. 2006, p. 255-7). There were many layers of deposits whose entire width reflected depositions at different instances of either numerous waves or up-rush and return flow.
The tsunami also transported rock sized matter as evidenced by isolated coral boulders deposited on the landward side of the beach (Brown 2005).
Reef surveys done in eight offshore islands and one mainland Aceh spots over a 650km distance indicated that the tsunami inverted coral colonies as well as the tree debris on the reef (Silver et al. 2006, p. 372). Most areas experienced severe tsunami damage and most corals were killed. According to Brown (2005), the earthquake resulted to the subsidence and uplift of some islands which affected the reef ecosystem dynamics.
For instance, the uplifted reef-flat corals thrived well, the reef-front corals were moved to the reef-flat region and the reef-flat groups were repositioned to the reef-front. The tsunami mechanically damaged the corals, rolled them and caused sedimentation in the reef from the land run-off. This affected the coral biodiversity of Indonesia (Brown, 2005, p. 373).
The tsunami also resulted to loss of natural ecosystems along the coastal line. A damage assessment carried out in Indonesia by the State Ministry of National Development Planning of Indonesia showed that a large percentage of the coral reefs, wetlands, seagrass beds and sandy beaches located in the Western Indonesian coasts were totally damaged (Brown 2005, p. 374).
According to Moore (2006), the tsunami had tremendous effect on the environment, especially on vegetation, forests and groundwater. Large agricultural and non-agricultural lands were damaged by the tsunami due to waterlogging, deposits of debris and sediment, soil erosion and salt deposits created by sea waves (p. 258).
Seawater inundation occurred on a large area and surveys have indicated that pH and EC values increased irrespective of how far the area was from the sea thus making most wells and open ponds to have high salinity levels. According to Shibayama (2005), the soil, as well as freshwater supplies, were poisoned by infiltration of saline water and salt deposits over land.
The increased soil salinity negatively affected crops and made lands unsuitable for farming. Seawater intrusion also affected large fields of agricultural and horticultural croplands adjacent to the seacoast. The tsunami also damaged drainage channels, irrigation channels and canals. For instance, canals were widened by invasion and retreating action of waves and later deposition with sand particles.
The land cover on sea, sand dune and saltpan areas were changed by the tsunami. For example, eroded sand particles carried by waves were deposited in the sea during the receding action thereby covering a large area of the sea with sand (Moore et al. 2006, p. 257).
According to Bappenas (2005), the flooded tsunami waters contaminated water supplies leaving many people without safe water as well as exposing them to water-borne illnesses such as typhoid, cholera and malaria. This was shown by World Health Organization reports which indicated that death of many people due to the tsunami made waterborne disease-outbreaks an issue of chief concern.
Bappenas (2005) further reports that 16-17 coral reefs in Maldives which were struck by waves, did not have fresh water causing them to be inhabitable for a long time. The water sources were contaminated by dead vegetation, human corpses and animal corpses.
Edwards (2005) cites the United Nations Environment Program (UNEP) report which indicated that about $675 million losses occurred in natural habitats and vital ecosystem dynamics from the 2004 tsunami damage to the Indonesian coast.
After the tsunami, principalities had difficulty in dealing with large debris combined with solid wastes like sand and sewage. The improper disposal of these wastes contaminated the soil and water supply systems.
Saatcioglu et al. (2005) cite a report from UNEP which indicated that the earthquake-damaged buildings, infrastructure and industrial sites including waste treatment centres and solid waste deposits causing oil and sewage spillage into the environment. This posed numerous health-related risks to humanity (p. 85-7).
According to Shibayama (2005), a lot of matter was possibly carried back during the return flow from land into the sea, leading to nitrification of Coastal waters as the matter contained nutrients and trace elements. This caused and continues to cause development of secondary consumers and a blossom of phytoplankton in the hypoxic conditions.
Therefore, after the tsunami, heavy deposits in forests altered the composition of species residing in forest soils. Richmond et al. (2006) conducted studies to determine effects of the tsunami on Biological Communities and Species and these studies showed that many species had been killed by the change in the environment (p. 248).
According to Saatcioglu et al. (2005), the tsunami was responsible for destruction of many structural and non-structural components. The waves of the tsunami imposed water pressures with great force on buildings, bridges and other structures near the coast which stirred up severe damage to infrastructure in surrounding land areas.
The breaking waves also exerted pressure on nearby structures along with hydro-dynamic pressures generated by high water velocity that caused full or partial crumple of buildings and other structures.
Saatcioglu also points out that damages in Thailand entirely resulted from water pressures which ranged from spontaneous gushy pressures of breaking waves at the shore to low dynamic pressures on land caused by reduced velocity of water and induced by surface friction. For instance, in the Indonesian region of Banda Aceh, floating debris made of large objects impacted on structures (p. 80-7).
According to Saatcioglu et al. (2005), widespread destruction and collapse of bridges due to tsunami waves was evident in Aceh province of Indonesia hence affecting transportation and relief efforts. Due to destruction of bridges, the Indonesian army put up bailey bridges to be able to find a way into nearby cement plants.
Therefore, transportation was greatly paralyzed and this endangered and hindered relief efforts. The worldwide humanitarian agencies were forced to clear the streets covered with debris from collapsed and damaged structures and vegetation. In addition, urban areas were inaccessible e.g. the 150km coastal road to Meulaboh, which was swept away by tsunami wave pressures and had its bridges weakened (p. 85-7).
The Indonesian storm drainage system had concrete open channels along the main streets roofed with solid slabs and prefabricated in most populous areas. According to Saatcioglu et al. (2005), the tsunami-damaged these drainage systems in Banda Aceh where waves broke cover-slabs and displaced them while debris and mud blocked channels leading to further flooding.
These drainage channels had to be thoroughly cleaned for reuse. Moreover, the water mains were damaged, resulting to disruption of water supply to Banda Aceh. Many main pipelines attached to bridges were said to have been broken and damaged by collapsed bridge materials or floating debris (Saatcioglu et al. 2005, p. 85-7).
Edwards (2005) points out that the United Nations Disaster Assessment and Coordination (UNDAC) participated in the Rapid Environmental Assessment (REA) of Aceh, Indonesia and reported that bulky debris and wastes were still evident in the destroyed settlements, along roads and adjacent to the ocean.
According to Edwards (2005), majority of the wastes and debris came from damaged buildings, soil and organic matter such as domestic waste and wood, and vegetation. In addition, the REA found out that household items, e.g. furniture, plastics, clothes, cars and damaged containers, as well as refrigerators, were part of the debris (this is shown in figure 2).
Edwards further points out that some areas reportedly had oil wastes and chemicals that mixed with water and sewage thus causing blockage of water sources like rivers and water channels (Edwards 2005). Following the tsunami, the wastes and debris created an ongoing problem in Indonesia due to improper management of the wastes.
Most wastes were dumped in the sea, rivers and beaches while others in emergency open dumps, thus causing fires. According to Edwards, there were three emergency open dumps in Banda Aceh and two old dumps at Gampong Jawa and Meulaboh and these open dumps were managed by local governments. However, waste management efforts were greatly affected as local governments lost a larger proportion of employees (Edwards 2005).
Figure 2: Waste and debris in Banda Aceh (Adapted from Edwards 2005)
Edwards (2005) cites reports from REA, which indicated that the tsunami exposed the environment to risks of chemical exposure, especially in places of usage, storage and manufacture. In addition, such environments had dangerous products e.g. lubricants, kerosene and diesel.
For example, chemical manufacturing industries, oil industries and the fishing industries are regarded as being the most important industries which underpin the economy of NAD province. However, these important investments were destroyed by the advancing waves of the tsunami, which produced a forceful, destructive and impacting force.
Therefore, the damage in Banda Aceh was devastating. The debris had oil patches due to oil spillage, which was also found on harbour water and mud. Surveys by Edwards (2005) showed that in Krueng Raya (40km North of Banda Aceh), some oil storage tanks were displaced by tsunami-waves and their contents spilt over (shown in Figure 3).
A similar case was witnessed in Meulaboh area where oil storage tanks were destroyed and dislodged with contents spilling over into the ocean without any trace of oil in the area (Silver et al. 2006).
Figure 3: A displaced fuel storage tank in Kreung Raya (Adapted from Edwards 2005)
Socio-Economic Impacts of The Disaster
The tsunami had devastating effects on the population and environment of affected zones. Shibayama (2005) highlights the fact that the effects were varied along the Sumatra West coast (due to the changing wave force and magnitude) with the adjacent regions being greatly affected.
The effects of the waves diminished away from the coastline, e.g. towards the southeast along Aceh to Sumut, thus the effects were minimal in these areas. Brown (2005) has argued that the height of water depended on the topography of the coast, the wave type and depth of the water (p. 372).
According to Bappenas (2005), the socio-economic activities were paralyzed along the coastline of NAD Province and Nias islands. Bappenas has further pointed out that the fishing industry, oil industry and chemical producing industries strongly influenced and dominated the economy of NAD province in Indonesia.
However, tables were turned especially due to the devastating effects of the tsunami, as all these industries bore the brunt of destruction. The agriculture sector, mainly fishing, was the greatest income-generating activity in 2004, making above 30% of regional gross domestic product (RGDP).
Among the industries mentioned above, the fishing industry was regarded as the most important industry which underpinned the Indonesian economy contributing approximately 160 million U.S dollars to the regional gross domestic product in Indonesia, especially in NAD province.
According to Bappenas (2005), the impact of the tsunami was felt in the fisheries industry where facilities and infrastructure were destroyed. Houses were also destroyed, displacing a larger proportion of the population and many people became jobless, especially those working in fisheries (Bappenas 2005).
NAD province had a total of 36, 597 hectares of fishponds for rearing sea bass, crab, milkfish and shrimp before the tsunami. When the tsunami occurred, vast aquaculture areas were totally damaged.
These were especially those adjacent to the coastal areas, including 20,000 hectares of fishponds and other fishery facilities (Moore et al. 2006, p. 256). According to Shibayama (2005), NAD province had large farms of rice and other plantations of coffee, coconuts and cashew nuts that were damaged along with livestock and poultry.
The islands of central Tapanuli, Sibolga and Nias Regencies were said to have a suitable environment for mariculture in their coastal waters such as rabbitfish, seaweed, sea bass and grouper (Brown 2005, p. 372). The province of North Sumatra is said to have had more than 1000 marine fish farms containing many units and about 18 800 fishing vessels before the tsunami.
According to Bappenas (2005), all the above were greatly affected, and about 9 563 units of fishing vessels, 38 fishing ports and landings were totally damaged when the tsunami struck.
In summary, the tsunami destroyed numerous structural and non-structural components which were disseminated as debris. The advancing and receding waves of the tsunami imposed water pressures which greatly and forcefully impacted on buildings, bridges and other structures near the coastal regions of different countries, Indonesia being the worst hit.
In addition, the water pressures stirred up severe damage to infrastructure in surrounding nations and land areas with devastating damage to the environment. Furthermore, the tsunami waves exerted pressure on nearby fishing facilities and other structures along with hydro-dynamic pressures produced by high water velocity which resulted to full or partial destruction of structures (Silver et al. 2000).
According to Saatcioglu (2005), the damages in other regions such as Thailand entirely resulted from water pressures which ranged from spontaneous gushy pressures of breaking waves at the coastal areas to low dynamic pressures towards land. Therefore, the force of impact was not only caused by water but also by the debris which impacted on the different structures.
Conclusion
Richmond et al. (2006) pointed out that the 2004 tsunami had significant effects along the Indian Ocean basin. Many nations in the Indian Ocean basin were greatly affected, with Indonesia bearing the greatest effect. Coastal properties, buildings, industries and ecosystem dynamics were destroyed. The extent of damage due to the tsunami varied with the size of waves and distance from the coastline.
For instance, the Indonesian coastline was hardly hit with the effect diminishing away from the coastline. There were lots of deposits of debris and waste which paralyzed activities including rescue efforts, transportation and agriculture. Contaminated water greatly posed health risks to survivors and economic activities were greatly affected with Aceh Province recording huge losses.
Therefore, the devastating effects of the tsunami hit many regions along the coasts of the Indian Ocean. These regions included “the west coast of Sumatra, the south coast of Java, the north and south coasts of West Nusa, Tenggara and East Nusa Tenggara provinces, the islands of Maluku and North Maluku Provinces, the north coast of Papua and most of the Sulawesi coastline” (Latief et al 2000, p. 28).
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