Residents’ Reactions to Earthquake Early Warnings in Japan

Abstract

This article empirically examines the effectiveness of earthquake early warning (EEW) in Japan based on experiences of residents who received warnings before earthquake shaking occurred. In Study 1, a survey (N = 299) was conducted to investigate residents’ experiences of, and reactions to, an EEW issued in Gunma and neighboring regions on June 17, 2018. The main results were as follows. (1) People's primary reactions to the EEW were mental, not physical, and thus motionless. Most residents stayed still, not for safety reasons, but because they were focusing on mentally bracing themselves. (2) Residents perceived the EEW to be effective because it enabled them to mentally prepare, rather than take physical protective actions, before strong shaking arrived. (3) In future, residents anticipate that on receipt of an EEW they would undertake mental preparation as opposed to physical protective actions. In Study 2, a survey (N = 450) was conducted on another EEW issued for an earthquake offshore of Chiba Prefecture on July 7, 2018. Results were in line with those of Study 1, suggesting that the findings described above are robust. Finally, given people's lack of impetus to undertake protective action on receipt of an EEW, this article discusses ways to enhance such actions.

A Review of the Technical and Socio-Organizational Components of Earthquake Early Warning Systems

“…In Japan, most of the literature shows that residents of the country agree with the implementation of EEW and find it useful. However, Nakayachi et al (2019) highlight that this is not always the case. In some regions of the country, the public does not believe that EEW alerts are effective, given their lack of detailed information about the strength of the incoming ground shaking and the expected arrival time.…”

“…The results of the survey indicated that 87% of the respondents were familiar with EEW systems and found them useful (Fujinawa and Noda, 2013). Positive public reaction and agreement toward EEW implementations in Japan can be also found in Hoshiba (2014), Nakayachi et al (2019), and Santos-Reyes (2019). In addition, Fujinawa and Noda (2013) highlighted that the warning issued during the 2011 minor tremor provided people with a valuable chance to prepare for the strong incoming shaking.…”

“…Warnings in Japan have clearly provided the population with enough time to implement risk-prevention strategies in past events, but Nakayachi et al (2019) carried out a survey that revealed a possible practical issue: users tend to primarily react mentally and not physically, and therefore remain still once a warning is issued, without taking any kind of protection actions (Nakayachi et al, 2019). The reasons why most of the interviewees did not react after the alert mostly include: 1) "I expected small intensity, so I thought it was not necessary to do anything"; 2) "I thought the place I was in was safe"; and 3) "I did not know what to do".…”

“…The reasons why most of the interviewees did not react after the alert mostly include: 1) "I expected small intensity, so I thought it was not necessary to do anything"; 2) "I thought the place I was in was safe"; and 3) "I did not know what to do". Reason 1) seems to be related to the fact that the warning just indicated "strong shaking incoming" without any specific information about the available warning time nor the actual intensity expected at the area (Nakayachi et al, 2019) (for instance in the case of EEW delivered via speakers). It is of great concern for the JMA that individuals do not know what has to be done once the alarm is triggered (Doi, 2011).…”

Practical limitations of earthquake early warning

“…In a recent study, Nakayachi et al (2019) noted that ''despite significant evidence of the utility of EEW for technical applications, there is limited information on the actual (not potential) effectiveness of EEW for personal protection'' (p. 2) and that ''how effective it actually is in practice is not yet clear.' 'Nakayachi et al (2019) concluded that primary reactions were passive in nature, and that the overwhelming majority of survey respondents stated that EEW enabled them to mentally prepare for shaking rather than to take action. Their study supports the notion that EEW can provide important emotional preparedness prior to shaking.…”