Tentative Report July 27, 2006 Indonesia- Japan Joint Survey on 2006 JAVA Tsunami Disaster Ministry of Marine Affairs and Fisheries , Indonesia

Port and Airport Research Institute, Japan Japan Society of Civil Engineers

1. Introduction

This is a tentative report to introduce the results of Indonesia- Japan Joint Survey on 2006 JAVA Tsunami Disaster. First of all, we like to express our deepest sympathy to the victims of this tsunami disaster.

The objective of the survey is to reveal the disaster by the tsunami. Researchers and engineers have to know what actually occurred by tsunamis to develop mitigation measures of tsunami disasters.

Engineers and researchers in Japan and Indonesia have a very long history of cooperation on the coastal disaster prevention studies including tsunami disasters. The Port and Airport Research Institute (PARI) and the Japan Society of Civil Engineers (JSCE) have a very active cooperative relation with the researchers and engineers in Indonesia, especially with the engineers of the Ministry of Marine Affairs and Fisheries (MMAF). This led to this joint survey of the tsunami disaster.

A destructive tsunami was generated by a subduction zone earthquake of M7.7 at 15:19, July 17 off the coast of west and central Java, Indonesia and attacked the areas from Garut through Ciamis to Yogyakarta which killed more than 500 people. Immediately after the tsunami attack we decided to conduct this joint survey. MMAF dispatched a survey team from July 19 and PARI and JSCE dispatched a team to join the survey from July 21. This emergency survey covered 200km-long coasts of Garut, Tasikmalaya, Ciamis and Cilacap Prefectures (Fig.1), and ended in July 25. The survey team consists of the following members: Indonesia

Subandono Diposaptono (Head ) Mr. Utantyo Wuryatmo Mr. Erva Kurniawan Miss Nelly Julius Japan

Dr. Shigeo Takahashi (Head) Mr. Daisuke Tatsumi

Prof. Koji Fujima With Assistance of Mr. Yasuo Takagaki (JICA) Mr. Ichiro Makuta (PCI) Mr. Sigit Widaryoko (PCI)

Survey Areas

Garut Tasikmalaya Ciamis Cilacap

Cilacap

Karangkadri

Windarapayung

Wetan

PangandaranSukaresik

Ciliang

LegokJawa

Ciparanti

Mandrajw

ava

Sindangkerta

Chieras

Karyam

ukti

Mancagahar

Cijam

be

Cikelet

200km

Fig. 1 Areas of the Survey

2. Results of the Survey 2.1 Cilacap

Figure 2 shows photos during the survey at a beach park in Windarapayung Wetan of Cilacap. Although the beach top is relatively high (4.0m from the water level during the Tsunami attack (0.75m above L.W.L.)) the tsunami attacked and run up the beach. A water mark of 6.9m high was measured near the top of the beach. It is said that more than 150 people were working to collect small crabs in the beach and 60 people were killed there. A destructive current due to breaking of the tsunami wave hit the rest room of the park as shown in the photo. The beach is like s small coastal dune and the backside of the dune has a downward slope connecting a low-lying rice field. The water current was intensified by the downward slope and washed the escaping people and made significant scouring. The damage in Cilacap area is relatively large in the eastern area and relatively low in the western area since the western area is covered by the Nusakambangan Peninsula.

2.2 Ciamis (Pangandran)

Figure 3 shows photos at Pangandran city of Ciamis where the number of casualties exceed 300. The city is located in a tombolo with a headland island of national park. At the south part of the city (near the headland) the ground level is low at 2.2 to 2.5 m and the tsunami broke near the shore and the current of about 1.5 meter thickness hit the houses and people. The tsunami attacked from west and east coasts of the city. In the city near the headland area the tsunami from west coast met the tsunami from east near the east coast. The figure shows very destructive power of the tsunami. It should be noted that the current carried the fishing boats and destroyed the houses by the collision impact. Significant damages occurred in the coasts of the Ciamis area in and around the coasts of Pangandran due to relatively low beaches and the high tsunami exceeding 5 meters. The total number of the casualties is more than 300 in this area.

Cilacap Windarapayung WetanWater Mark 6.9 m

Ground Level 4.0 m

Small crab collecting people died (60/150 people), and damage to park facilities

Figure 2 Windarapayund Wetan, Cilacap

Pangandaran

Figure 3 Pangandran

2.3 Tasikmalaya Figure 4 shows photos near a hotel

we stayed at Sindangkerta village of Cipatatujah. Although the tsunami was relatively high (water mark here exceeding 5m) due to relatively high ground level, the inundation is not significant. The hotel could operate just after the tsunami.

However, low-lying areas such as lands near a river mouth were suffered from significant inundation damages as in Pangandran. The total casualties in Tasikmalaya is more than 100. Especially many people were killed Cipatatujah village and Cimanuk village of Cikalong. 2.4 Garut Figure 5 shows photos at Sayangheulang park of Mancagaha in Pemeungpeuk. Due to relatively high beach ground the inundation is limited here. The damage in Graut Prefecture is limited. Especially People in the western area from this park could not notice the tsunami compared with the ordinary astronomical tide (2m) and high waves. 2.5 Result of Tsunami Water Mark Survey Figure 6 shows distribution of water mark height by tsunami. Blue lines show the results of Japanese team, and red circles the results of Indonesian team. The results of Japanese and Indonesian team are slightly different because two teams selected different water marks. However, the variation pattern of survey results is similar. In the initial report of media, tsunami height was reported as 2 to 3m. However, our measured heights were 2 to 8m. The present event was not small, but big enough to provide the serious damages. The damages of Pangandran were most serious, and the measured heights were high. However, the heights observed at Pangandran were not exceptionally high, the similar results were recorded also in the other sites. The reason why Pangandran suffered so severe damages might be the high population density and low ground level.

Cipatatujah Sindangkerta Ciparengkok Hotel

Water Mark 5.4m

Ground Level 4.1m

Small inundation Figure 4 Cipatatujah

Pameungpeuk Mancagahar Sayangheulang

Water Mark 5.2m

Ground Level 4.5m

Small inundation Figure 5 Pameungpeuk

3. Concluding Remarks The summary of damages is as follows: 1. High Tsunami and strong tsunami breaking currents attacked the houses and

people near and in the beach resulting in more than 500 casualties. 2. Damages to houses and people increased due to impact of rushing boats. 3. The currents were intensified due to the downward slope of dune backside carrying

the people to wet areas behind the sand. 4. People in the sea collecting small crabs were attacked by the tsunami and many of

them became the victims. 5. Rice paddies were damaged due to inundation, sometimes with contaminated

water. 6. Seawalls were damaged due to tsunami and scouring was observed in the beach and river mouth.

We consider further studies are needed to develop mitigation measures against

tsunamis. Especially the following items should be considered: 1.Tsunami breaking and current intensity 2. Drifting of boats and collision impact 3. Real-time prediction of tsunami 4. Numerical simulation for tsunami damages

Acknowledgements Finally, we like to express our gratitude to the government of Indonesia and many

Indonesian people who helped the survey. We like also express our thanks to the people of Japanese Embassy, JICA (Japan International Cooperation Agency) and PCI (Pacific Consultants International).

Figure 6 Tsunami Water Mark Height of Garut, Tasikmalaya, Ciamis and Cilacap Pameungpeuk