illustration during a tsunami in Aceh on 26 December 2004 | photo by
The Sumatera International Tsunami Survey Team (SITST) led by Yoshinobu Tsuji of the University of Tokyo with nine other members belonging to Japanese scientists, including six from Indonesia, Two from France and two from the United States, conducted a survey on 20-29 January 2015 .When conducting the survey they divided several more teams to collect information on the impact of the tsunami in Aceh. Some of these teams were tasked with finding information about wave heights on the coast and on land, sedimentary sediments, tsunami wave energy on buildings, pnti decreases, erosion, flow direction, elevation of water level relative to the center position of the sea at maximum distance on land and distance achieved tsunami on the ground, they also conducted a survey by interviewing surviving witnesses.
illustration during a tsunami in Aceh on 26 December 2004 | photo by
Decreased land due to tsunami
Experts estimate that the type of megathrust that causes a tsunami will raise the seafloor over the cause of the earthquake and cause land subsidence near the coast. Evidence of land degradation is very visible on the root tree and the bottom of the stem is submerged in sea water. Coastal land is estimated to have dropped to 1-2 m in some places and 28 to 57 cm of land subsidence detected at the beach. So no wonder after the earthquake and tsunami in Aceh suffered a lot of land decline on the island of Sumatra.
The coast of Sumatra has been significantly altered by the tsunami. Coastlines are eroded, the sand is brought to the mainland, and the coastal plains are inundated. Compared to the relatively rapid erosion and sediment deposition caused by the tsunami, the coastal decline resulting from erosion and coastline retreat for weeks and months to accompany the tsunami. In addition, the beach began to re-establish itself a few weeks after the tsunami, with the possibility of adding sand from the nearby coast. These re-established beaches migrate inland.
Puddle of sea water
The puddles generated by the tsunami cover a wide coverage area in Aceh, so it can be easily seen in satellite imagery. On land, this tsunami puddle can be seen from the trash trail left behind, the effects of puddles and sediments precipitated by waves, and plants that die from salt water. In Kota Banda Aceh itself, the puddle distance reaches 6.5 km from the coastline. The direction of the grass fall, the direction of falling trees, and the direction of the bent coastal structure show the direction of the tsunami wave. The researchers saw that the tsunami waves moved around a natural barrier and flooded the area behind it.
The height of the tsunami is measured by seeing traces of water on the walls of buildings and branches of broken trees or debris left behind between branches of trees. The building or the tree is certainly that still standing. Tsunami height measurements were made using a device called the laser rangefinder. From the tool they get the height values of the tsunami. Maximum tsunami altitude is found on the west coast of Aceh, measured in cement plant buildings, as high as more than 30 m. While deforestation by the tsunami shows a tsunami height of 15-20 m. The height of the tsunami that hit the northern coast is lower or about 10-12 m tall. Aceh's relatively sloping and flat condition caused the tsunami to go further inland.
illustration during a tsunami in Aceh on 26 December 2004 | photo by
Arrival Time and Wave Behavior
The tsunami arrived about 15 to 20 minutes after the earthquake shock. This figure was obtained based on interviews with eyewitnesses. From eyewitnesses, it is also known that the tsunami waves that struck there were three times. Many buildings are still standing when shaken by the earthquake, but destroyed by tsunami waves. This is understandable considering the affected area has a low elevation. That way, when the tsunami struck Banda Aceh, the water did not recede before the second tsunami wave arrived. The second wave comes over the first wave, the third wave comes over the second wave, resulting in wave accumulation.
illustration during a tsunami in Aceh on 26 December 2004 | photo by
