Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanANALYSIS OF SHIP EVACUATION IN TSUNAMI
USING AIS DATA

Shigeaki SHIOTANI1, Hidenari MAKINO2
1Professor, Organization of Advanced Science and Technology, Kobe University,
shiotani@maritime.kobe-u.ac.jp
2
Research Fellow, Graduate School of Maritime Sciences Kobe University,
makino@port.kobe-u.ac.jp

ABSTRACT: This research investigated the evacuation behaviors of the vessels using
the data obtained from AIS, during the major tsunami warning announcement. The resultshows that most vessels in the port started evacuating approximately 30 min after themajor tsunami warning announcement and completed evacuation 120 min after theannouncement. This contributed in understanding the actual status of the vessel
evacuation. In addition, the travel paths of each vessel revealed the influence of thetsunami on the vessels.
Key Words: Great East Japan earthquake, Tsunami, AIS, Ship evacuation

INTRODUCTION
The direction and velocity of vessels at sea change depending on external forces including wind waves,surges, and tides. The pre-eminent effect of these forces can result in disasters such as shipwrecks andcollisions at coastal areas, according to Japan Coast Guard. In particular, the submarine topography ofthe coastal areas of Japan, where earthquakes and tsunamis frequently occur, transforms tsunamis
entering the bay from the ocean into large waves. This results in environmental destruction andenormous damage of vessels underway or at anchor, according to Y. Kugou (2011). A gigantic
earthquake occurred in the Tohoku and Kanto areas on March 11, 2011 and is considered an event thatoccurs once in 1,000 years. Subsequently, the major tsunami warning and tsunami warning or advisorywere announced to all coastal areas along the Pacific Ocean. This study investigated the evacuation
actions of the vessels at the Tokyo bay where major tsunami warnings were announced. The resultshows behaviors unique to emergency evacuation situations. In addition, this study draws an inference
on the local conditions of tsunamis by analyzing the evacuation status of the vessels.

STATUS OF THE TSUNAMI CAUSED BY THE GREAT EAST JAPAN EARTHQUAKEThe epicenter of the 9.0-magnitude earthquake on March 11, 2011 at 2:46 pm was off the Sanriku
Coast. Accordingly, the coastal areas along the Pacific Ocean, especially the Hokkaido and Tohoku

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regions, experienced different sizes of tsunamis. At some locations, the tsunami reached a height ofgreater than 10 m as reported by T. Nagai (2011). The coastal regions along the Pacific Ocean inIwate, Miyagi, and Fukushima Prefectures received the major tsunami warning at 2:49 pm, 3 min after
the earthquake. In addition, all coastal areas along the Pacific Ocean received the major tsunami
warning followed by the tsunami warning or advisory, 44 min after the earthquake as reported by
Japan Meteorological Agency (2011). Fig.1 shows a tsunami warning figure which JMA announced at
4:13 pm on March 11, 2011.In this figure, red lines indicate the major tsunami warning. This figure
shows that major tsunami warning was issued almost all the area of the Pacific coast in Japan. About
the tsunami in Tokyo Bay, the first wave was observed at the Yokohama observatory at 16:09. Thewave height at this time was +0.8m. Moreover, the maximum wave was observed at 17:37. The wave
height at this time was +1.5m.

Fig. 1 Tsunami warning figure which JMA announced at 4:13 pm on March 11, 2011.

ANALYSIS OF SHIP EVACUATION USING AIS DATA
Vessels are usually undocked and evacuated outside the port upon the arrival of tsunamis because
anchoring inside the port is extremely dangerous. This study analyzes the movements of each vessel in
the Tokyo bay, which received the major tsunami warning, by using the data obtained from theAutomatic Identification System (AIS).
AIS is a type of automatic dependent surveillance-broadcast technology that provides useful
information such as names of the vessels and call signs for distinguishing ships as well as locations,velocity, and directions of the vessels, as referred to at the literature of International Maritime
Organization (2003) or others. The device automatically transmits information pertaining todestinations and loadings to the neighboring vessels. IMO (International Maritime Organization)
mandates sequential loadings for target vessels (passenger ships and ships with a total of more than
300 tons for international voyages and vessels with a total of more than 500 tons for non-internationalvoyages). The data received by AIS is broadly classified into static data (such as names of the vessels
and the call signs), dynamic data (such as the current locations, navigation speed, and directions), and476

the voyage related data (such as the draft and destinations). Table 1 shows the data contents of AIS. On
the basis of the data, we depicted the conditions with the frequent changes in the motion of the vessels
equipped with AIS. In addition, we selected the vessels that were evacuated because of the tsunami
and analyzed the distribution of the areas and the distance to which they were evacuated.
Table 1 Contents of AIS data

ANALYSIS RESULTS
Fig. 2 shows an example that depicts the status of emergency evacuation of each vessel on the basis of
the AIS data obtained from the Tokyo bay. Each black arrow in these figures indicates a going vessel,and each red circle indicates anchor vessels, and also the broken lines show the paths of the vessels
during a 30-min period. Fig. 2(a) shows the conditions around the port at 4:02 pm, 30 min after themajor tsunami warning, and indicates that each vessel had started preparing for evacuation. This figure
also shows several vessels that were preparing for evacuation. Fig. 2(b) depicts the condition at 5:32
pm, 120 min after the major tsunami announcement. In the region shown with the red circle in thisfigure, many oil industrial complexes exist and almost all the vessels of the neighborhood havecompleted evacuation to the outside of each harbor.
Fig. 3 shows the conditions around the closed-off section of Tokyo bay at 7:02 pm, 210 min afterthe major tsunami warning. In this figure, each black arrow indicates a going vessel, and each red
circle indicates anchor vessels, and the broken lines show the paths of the vessels during a 30-min
period. In Chiba port, all the vessels that can be confirmed from AIS data moved to the central part ofclosed-off of Tokyo bay. Furthermore, it is recognized that those vessels have completed evacuation.
The numerousness of the vessels especially shown with the red triangle in this figure is remarkable.
Since such a ship state cannot be seen probably at usually situation, it is thought that it is the feature ofevacuation action of the vessel after a tsunami warning announcement. About the next situation fromaround 9:00 pm, almost all vessels were carrying out the anchoring. Therefore, the ship state where theflow of vessel traffic inside the Tokyo bay had almost stopped has been checked. This state continued
till March 13 of which the tsunami warning was canceled.

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TokyoYokohama
Chiba(a) 16:02
Tokyo

Yokohama
Chiba(b) 17:32
Fig.2 Ship situation in Tokyo bay on March 11, 2011478

Chiba portChiba city

Fig.3 Ship Evacuation situation in closed-off section of Tokyo bay
Fig. 4 shows the condition of vessels at the time of usual, and the time of emergency in Tokyo Bay.
In each figure, each black arrow indicates a going vessel, and each red circle indicates anchor vessels
and the broken lines show the paths of the vessels during a 30-min period. Fig. 4 (a) shows the cruise
situation of the vessel on March 4 which one week before the earthquake disasters. Both Fig. 4(a) andFig. 4(b) are in the situation of the vessel at 9:00 pm. Both figures are compared and a difference clear
about the number of anchoring vessels and its anchorage area is distinguished. As Fig. 4(a) showing,
anchoring vessels are the anchor stay aiming at entry into the port near harbor boundary of each harbor.
On the other hand, vessels are the anchor stay aiming at the evacuation as Fig. 4(b) showing. Moreover,
289 vessels were checked from AIS data about the number of vessels in Tokyo Bay at 9:00 pm on
March 4. Meanwhile, no less than 331 vessels were checked at 9:00 pm on March 11 at the time ofemergency situation.
The result of having investigated the number of vessels which goes in and out into Tokyo Bay ofboth days using AIS data is shown in Fig.5. This investigation was conducted by statistics comparisonof the passage vessel of the entrance of Nakanose route shown in the red square region of Fig. 4 in
3:00 pm to 23:59 pm of both days. Fig. 5(a) shows the number of vessels entered in Tokyo Bay. It
turns out that there are many vessels included in Tokyo Bay from 6:00 pm to 10:00 pm as a feature on
March 11 which it was under the emergency situation. In it, the vessel which was cruising towards
each harbor of the Tohoku district as a destination existed. This means that the vessel from which it
was departing towards the Tohoku district as a destination got to know the earthquake and the situationof tsunami, changed the destination, and went into Tokyo Bay. Moreover, Fig. 5(b) shows the numberof vessels left from Tokyo Bay. As this result, it turns out that March 4 was 92 boats and March 11 wasonly 39 boats. From this result, it is guessed that the vessel usually left towards the outside of Tokyo
Bay as that cause had stayed and taken evacuation in the inside of the bay.

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TokyoYokohama
Chiba(a) 21:00 on 4 March 2011

TokyoYokohama
Chiba(b) 21:00 on March 11, 2011
Fig.4 Comparison of ship traffic flows in Tokyo bay of emergency and usual time480

(a) A number of entered ship to Tokyo bay(b) A number of left ship from Tokyo bay
Fig.5 Comparison of number of ship on March 4, 2011 and March 11, 2011

CONCLUSIONS
Using the data obtained from AIS, this study investigated the evacuation behaviors of the vessels
equipped with AIS in Tokyo bay during the major tsunami warning announcement. The result showsthat most vessels started evacuating approximately 30 min after the major tsunami warning
announcement and completed evacuation 120 min after the announcement. This contributed inunderstanding the actual status of the vessel evacuation.
Based on the results obtained in this study, our future study will conduct further analysis for
preparing a manual that provides appropriate evacuation instructions during a tsunami. The analysis
will provide more comprehensive perspectives including evacuation behaviors of all vessels.

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REFERENCES
International Maritime Organization (2003). “Guidelines for The Installation of A Shipborne
Automatic Identification System (AIS)”
http://www.imo.org/OurWork/Safety/Navigation/Documents/227.pdf
Japan Meteorological Agency (2011). “Tsunami Information” http://www.jma.go.jp/jp/tsunami/.
T. Nagai (2011). “The History and Current Status of Tsunami Observation by the NOWPHAS andTsunami Wave Formation Related to the Great East Japan Earthquake in 2011 Captured by theNOWPHAS” Lecture Document Collection of Review Meeting on the Great East Japan
Earthquake, pp. 9-17.
Y. Kugou (2011). “Disaster Conditions in the Pilot Areas in the Tohoku Region” Lecture Document
Collection of Review Meeting on the Great East Japan Earthquake, pp. 49-56.

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