Subjective Estimation of Risks and Assessment of the Information Included in the Tsunami Warning System by Students in Universities Located Inside and Outside Regions Damaged by the 2011 off Pacific Coast of Tohoku Earthquake in Japan

Erina GyobaInternational Research Institution of Disaster

Sciences, Tohoku-University

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- Introduction -　 　 Before and at the time of the 2011 off Pacific Coast of

Tohoku Earthquake occurrence, information about tsunami heights was released in quantitative values

Examples

Iwate 　　Miyagi 　　　 Fukushima

It is surmised that already reached14:57

15:07

3m6m1m

An earthquake occurred at 12:00, today.The epicenter is Pacific off of Sanriku (North Latitude 38.0,East Longitude 142.9, 130km of East southeast of Oshika Peninsula). The depth of epicenter is 10km and the scale of the earthquake is estimated as M8.9.

The JMA reviewed and found that these quantitative values were insufficient in urging people to evacuate, since actual tsunami heights greatly exceeded the forecasted heights during the 2011 Earthquake.

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―New Version of Tsunami Warning System ー　 　 On March 7, 2013, the JMA released a new version of the tsunami

warning system that emphasizes “immediate evacuation” and employs three types of qualitative expressions to describe tsunami heights:

Criteria Qualitative Expression

Over 3 m to Over10 m Huge

Over 1m to Over 3m High

Over 0.2m 〜 1m (No Adjective)

Examples

Iwate 　　　Miyagi 　　　 Fukushima

It is surmised that already reached 14:57

15:07

　　　　 High Huge

An earthquake occurred at 12:00, today.The epicenter is Pacific off of Sanriku (North Latitude 38.0,East Longitude 142.9, 130km of East southeast of Oshika Peninsula). The depth of epicenter is 10km and the scale of the earthquake is estimated as over M8. 3

―Background ー Information about a disaster should be delivered in a way that allows

people to take precise action to reduce and to avoid possible damages(Katada & Kanai 2009; Gyoba & Muramoto 2013).

Young people have difficulty perceiving unusual situations and taking precise actions in emergency situations, although they may know of the disaster(Student Life Department of Waseda University 2011)

University students do not have as many opportunities to participate in disaster prevention drills and are not particularly interested in disaster information, even if they have general knowledge of the disaster (Oki 2012)

Such tendency is stronger among university students who have not experienced severe disasters or have not had lessons in disaster prevention.

Such activities are needed to improve disaster prevention education, including proper dissemination of information provided by public institutions, such as the JMA, broadcasting organizations, and so on.

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―Goal of This Research ー Experiences with and exposure to disaster information largely

differed among University Located Inside and Outside of Damaged area, thus the measure to utilize and supply disaster information each other(Gyoba, 2012).

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The present study aimed to investigate subjective risk estimation for qualitative descriptions in the JMA’s new tsunami warning between university students located inside (Tohoku) and outside (Kyushu) the areas damaged by the 2011 off Pacific Coast of Tohoku Earthquake.

―Location of Universities ー

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Sendai City(TU and TFU University are here)

Epicenter of theMarch 11 2011Earthquake

Fukuoka City(KU University is here)

Tohoku Area

Kyushu Area

ー Method ー

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ParticipantsInside Damaged Area:159 were university students in the Tohoku area (105 were students of TU university, and 54 were students of TFU university)Outside Damaged Area: 199 were university students in the Kyushu area(all students were enrolled in KU university).Period

May 13,2013 to June 24,2013

Contents of Questionnaire

1 Five questions that asked students to make subjective estimations of tsunami heights using numerical values

2 Multiple-choice question and a free-answer question that surveyed the degree of effectiveness of the previous and new tsunami warning systems

3 Free-answer questions asked the students to write the advantages of and ways to improve the new tsunami warning system

―Examples of Questions ー

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(Question 1Please describe your estimation of the tsunami’s height when you received the “Huge tsunami” warning information. ( )m 〜 ( )m〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜Question 2Which of the previous version (A) and the new version (B) shown in the attached document is more effective to allow people’s appropriate actions? Select one corresponds to your answer from the choices below.

a.A(Previous) Version 　 b. B(New) Version c. Not effective either d. No idea〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜〜Question 3What points are effective or needed to improve in the new version (B) do you think? Please describe in the square below.

―Attached document ー

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(A)Previous Version (B) New Version

The tsunami corresponding to the class of 2011 Tohoku Earthquake is approaching to the coast of Japan. Evacuate immediately!

[Predicted Reach time and Height of the Tsunami] [Predicted Reach time and Height of the Tsunami]

The Areas Reach times Heights The Areas Reach times HeightsIwate Already

reached3m Iwate Already

reachedHuge

Miyagi 12:11 6m Miyagi 12:11 Huge

Fukushima 12:21 3m Fukushima 12:21 Huge

Pacific Coast ofHokkaido

12:41 1m Pacific Coast ofHokkaido

12:41 High

Pacific Coast ofAomori

12:41 1m Pacific Coast ofAomori

12:41 High

Ibaragi 12:41 1m Ibaragi 12:41 High

Chiba- Uchibo 12:41 0.5m Chiba-Uchibo 12:41

Ogasawara Islands 12:51 0.5m Ogasawara Islands 12:51

― Results ―

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Tohoku Kyushu0

5

10

15

20

Minimum height Maximum height

*

+

m

Figure 1: Subjectively estimated minimum and maximum tsunami heights given by the students in Tohoku and Kyushu area when informed of a “huge” tsunami.

Minimum tsunami height (t= 1.23, df=350, p=0.1)Maximum tsunami height (t=1.94, df=296, p=0.03)

― Results ―

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Tohoku Kyushu0

2

4

6

8

10

Minimum height Maximum height

*

+

m

Figure 2: Subjectively estimated minimum and maximum tsunami heights given by the students in Tohoku and Kyushu area students when informed of a “high” tsunami.

Minimum tsunami height (t= 1.40, df=340, p=0.07)Maximum tsunami height (t=1.90, df=325, p=0.03)

― Results ―

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Tohoku Kyushu02468

101214161820

Minimum height Maximum height

m

Figure 3: Subjectively estimated minimum and maximum tsunami heights given by the students in Tohoku and Kyushu area when informed of a “Major Tsunami Warning.”

Maximum tsunami height (t = 1.34, df=298, p=0.09)

― Results ―

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Tohoku Kyushu0123456789

10

Minimum height Maximum height

****m

Figure 4: Subjectively estimated minimum and maximum tsunami heights given by the students in Tohoku and Kyushu area when informed of a “Tsunami Warning”

Minimum tsunami height (t= 2.72, df=343, p = 0.003)Maximum tsunami height (t=3.29, df = 329, p = 0.0006)

―Results －

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Tohoku Kyushu0

0.51

1.52

2.53

3.54

4.55

Minimum height Maximum height

****m

Figure 5: Subjectively estimated minimum and maximum tsunami heights given by the students in Tohoku and Kyushu area when informed of a “Tsunami Advisory”

Minimum tsunami height (t= 2.17, df=328, p = 0.02)Maximum tsunami height (t =3.54, df = 348, p = 0.0002)

―Results －

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Kyushu

Tohoku

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

A Version(Previous) B Version(New)Not effective neither No idea

Figure 6:Distribution of answers evaluating the previous and new tsunami warning systems.(χ2 = 0.24, df = 3, n.s.)

―Categories of advantages of and ways to improve for the new tsunami warning system ー

The advantages (1) “It facilitates empirically acquired actions”, (2) “It makes easy to perceive risks”, (3) “The expression ‘huge’ is effective”, (4) “The information on the 2011 Tohoku Earthquake included in the new warning system is effective”, and (5) “Others”

Ways to improve (1) “It tends to arouse fear excessively”, (2) “It is rather vague and ambiguous”, (3)”It needs to take into account different criteria for ‘huge’ and ‘high’“, (4) “Means of escape and refuge facilities should also be indicated”(5) “The areas the tsunami will reach should be described in more detail”(6) “Its effectiveness would not be long-lasting”, and (7) “Others.

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The category “others” includes various answers given by dozens of students in each group.

The advantages “It is better than previous version”, “It raises people’s attention”, etc.

Ways to improve “Quantitative values in the previous warning system should be displayed at the same time”, “The warning system should be exaggerated in order to force people to evacuate immediately”, etc.

―Results －

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Kyushu

Tohoku

0%10%

20%30%

40%50%

60%70%

80%90%

100%

It allows emprical action Easy to perceive risks"Huge" is effective "2011 Earthquake" is effectiveOthers

Figure 7. Percentage distributions of the advantages of the new tsunami warning system.(χ2=3.01, df= 4, n.s.)

―Results －

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Kyushu

Tohoku

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

It tends to enlarge fear Too abstract

Take account of individual Standards Describe detail areas the tsunam reaches

Describe measures and spots to evacuate Long-Lasting effectiveness

Others

Figure 8. Percentage distributions of the disadvantageous points of the new tsunami warning system.

―Discussion ー University students of Tohoku• They tended to have lower estimates of tsunami heights than students in the

Kyushu area when they received the qualitative expressions. • They assessed the new qualitative version of the tsunami warning system as

more effective than the previous quantitative version

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• They tend to avoid relying solely on the numerical value warnings because they have learned that the disaster is often severer than predicted in the previous version through university disaster prevention education, local media, which broadcasted actual situations of the damaged areas, or their own actual experiences.•They suggested that the new tsunami warning is not a permanent solution since the new tsunami warning system mentions information on the 2011 Tohoku Earthquake as a headline example.

―Discussion ー　 University students of Kyushu• They tended to estimate tsunami heights more excessively, especially

when they were informed of a “huge” tsunami• They assessed the new qualitative version of the tsunami warning as more

effective than the previous quantitative one.• Several students pointed out that the information about the means to

evacuate and refuge facilities should be included in the new tsunami warning.

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• They might not be able to visualize the exact height of tsunami inducing severe damages, since they have not yet had first-hand experience with such disasters.

• They might regard qualitative expressions such as “huge” or “high” to prompt people to evacuate from unknown disasters.

• They tended to require more concrete and precise information for appropriate evacuation procedures from public institutions, including the JMA. 　

ー Conclusion ー• The present study revealed the gaps in estimating risks from disaster

information between people living inside and outside the damaged areas.

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• Bridging the gaps requires more than fundamental knowledge about disaster information and warning systems provided by public institutions.

• It also requires vital connections between young people who have disaster experience and those without, especially for university students who have not yet formed tight connections with local communities.

Further investigations should include a survey not only of university students but also of the elderly, children, and people living in regions with a history of frequent disasters or high risk of future incidents.

ー References and Acknowledgements ー• Gyoba, E., & Muramoto, T. (2013). Analyses of the comprehension and recognition of the instructions in

educational material for disaster prevention using an assessment model based on cognitive and motivational factors. International Journal for Cross-Disciplinary Subjects in Education, 5 (1), 1099-1107. Basildon: Infonomics Society.

• Japan Meteorological Agency (2013). About renewed tsunami warning system (in Japanese), Official Website of Japan Meteorological Agency, http://www.seisvol.kishou.go.jp/eq/tsunami_keihou_kaizen/

index.html (Reference Date: Dec 13, 2013). Tokyo: Japan Meteorological Agency.• Katada, T., & Kanai, M. (2009). Fundamental research about social technology that concerned safety and

relief in the actual condition of prevention for tsunami disaster information (in Japanese). Journal of Japan Society for Disaster Information Studies, 7, 37-42. Tokyo: Japan Society for Disaster Information Studies.

• Oki, S. (2012). Estimating probability of huge earthquake occurrence and its damage do not lead to enhancement of potential for disaster prevention (in Japanese), Article from Nihon-Keizai News, http://www.nikkei.com/ article/DGXNZO47420990Z11C12A0CR8000/ (Reference Date: Nov 18, 2013), Tokyo: Sankei Shimbun Co., Ltd.

• Student Life Department of Waseda University (2011). Consciousness for Great East Japan Earthquake 2011 (in Japanese), Waseda Weekly Special Edition (published July 21, 2011), Tokyo: Waseda University.

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References

AcknowledgementsThis research was supported by a JSPS postdoctoral fellowship (244610) to Erina Gyoba. The author thanks Prof. T. Muramoto, Prof. F. Imamura, Prof. Y. Hakoda, Associated Prof. Y. Sakaki, and Dr. H. Shibata for their generous support.