https://doi.org/10.20965/jdr.2019.p0531 An Analysis of Web Coverage on the 2018 West Japan Heavy Rain Disaster Survey Report: An Analysis of Web Coverage on the 2018 West Japan Heavy Rain Disaster Shosuke Sato† and Fumihiko Imamura International Research Institute of Disaster Science (IRIDeS), Tohoku University 468-1 Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-0845, Japan †Corresponding author, E-mail: [email protected] [Received November 6, 2018; accepted January 30, 2019] 600 This study analyzed quantitative big data from web 545 at maximum す᪥ᮏ㇦㞵䠄 ᖺ䠅 news on the West Japan Heavy Rain disaster for a two- (3rd day) West Japan Heavy2018 Rain (2018) month period. The retrieved information was com- 500 ⇃ᮏᆅ㟈䠄Kumamoto2016 Earthquakeᖺ䠅 (2016) ᪂₲┴୰㉺ᆅ㟈䠄Niigata-Chuetsu Earthquake2004ᖺ䠅 (2004) pared with previous natural disaster coverage. The re- 366 at maximum sults indicated the following. 1) For natural disasters 400 (8th day) that had occurred over the past 15 years, the “half-life 300 period for media exposure” (i.e., the period in which Half-life period of West the amount of news reporting halves) was approxi- 176 at maximum Japan Heavy Rain 200 (2nd day) (3rd time): 24th day Numberarticles of mately one week, while the half-life period of web me- Half-life period of Kumamoto (2nd time): 7th day dia exposure on the West Japan Heavy Rain disaster 100 was 24 days. Thus, the West Japan Heavy Rain disas- Half-life period of Chuetsu: 7th day ter appeared to be the most significant social concern 0 since the Great East Japan Earthquake. 2) The West 1 3 5 7 9 111315171921232527293133353739 Japan Heavy Rain disaster was large enough to affect ⅏ᐖⓎ⏕䛛䜙⤒㐣᪥ᩘ䠄⅏ᐖⓎ⏕᪥䜢Days after occurrence of disaster1᪥┠䛸䛧䛶䠅 (The disaster occurring day was counted as first day.) both the Chugoku and Shikoku Districts, but the avail- able human support was comparable to the extent of Fig. 1. Time-series change concerning Yahoo! News ar- the human and material damages as well as the related ticles on the West Japan Heavy Rain disaster, Kumamoto amount of media coverage. No significant regional dif- Earthquake, and Niigata-Chuetsu Earthquake. ferences in the amount of media coverage or support were found. 2. Data Keywords: disaster information, web coverage, the 2018 West Japan Heavy Rain, media exposure This study focused on news coverage of the West Japan Heavy Rain disaster as released by Yahoo! News. The dataset was collected through an “OR” search using the 1. Introduction keywords “heavy rain (Japanese text: ‘Bg1+’)” and “heavy rainfall (Japanese text: ‘9k1+’)” to obtain news that was There has been significant web news coverage on every released from July 5, 2018 to September 6, 2018. Articles disaster since the Niigata-Chuetsu Earthquake in 2004. related to the West Japan Heavy Rain disaster were then The first author of this paper used these news sources selected for analysis. We then archived the data and de- to analyze social recognition of the covered disasters, veloped an analytical database consisting of release dates thereby providing a better understanding of these situa- and times, news media sources, headlines, and articles. tions as information sources [1, 2]. Web news provides useful linguistic data for understanding real-time events. This aids in analyzing and discussing social responses at 3. Time-Series Trend the time of their occurrence. This study analyzed and characterized big data from web news coverage of the Figure 1 shows a comparison of the number of arti- July 2017 heavy rain (referred to in this paper as the West cles on the West Japan Heavy Rain disaster, the Niigata- Japan Heavy Rain in 2018) for a two-month period after Chuetsu Earthquake in 2004, and the Kumamoto Earth- the disaster. quake in 2016 [3, 4]. All articles on the two earthquakes were collected from Yahoo! News. The number of articles on the Niigata-Chuetsu and Ku- mamoto earthquakes peaked between two and three days after the events (Fig. 1) [3]. This is because the public was unaware of these disasters immediately after, but gradu- Journal of Disaster Research Vol.14 No.3, 2019 531 © Fuji Technology Press Ltd. Creative Commons CC BY-ND: This is an Open Access article distributed under the terms of the Creative Commons Attribution-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nd/4.0/). Sato,S.andImamura,F. 10,000 10,000 10,000 Number of completely Number of completely Number of victims destroyed and half destroyed destroyed houses Kurashiki houses and houses with Kurashiki inundation above floor level Kurashiki Hiroshima Hiroshima Hiroshima 1,000 Kure 1,000 Kure 1,000 Kure Uwajima Uwajima Uwajima OzuSeiyo Sakamachi SeiyoSakamachiMihara Seiyo OzuSakamachi OkayamaSoja Mihara Okayama Soja Mihara Soja Okayama MatsuyamaHigashihiroshima Higashihiroshima MatsuyamaHigashihiroshima TakahashiFukuyama Kumano FukuyamaKumanoTak ahas hi KumanoTak ahasFukuyama h i Fuchu Fuchu FuchuFuchu Onomichi Kaita Onomichi Kaita Ibara Ibara IbaraKaita 100KasaokaNiimi 100 Kasaoka 100 Niimi Kasaoka Imabari Ts uyYakage a maEdajima Iyo ImabariTsEdajima uy amaMiyoshiYakage Takehara Takehara Yahatahama Takehara Kagamino Shobara KagaminoKihoku Maniwa Kagamino KihokuMimasakuMatsuno Asakuchi Akitakata Akitakata Tamano AsakuchiAkitakataWakeManiwa MisakiKamijimaUchiko Number Number of articles Number of articles Number of articles HatsukaichiBizenOtake 10 10 10 KibichuoAinanSera Satosho IkataNishiawakura Osakikamijima Osakikamijima R=0.952 R=0.809 Akaiwa R=0.843 1 1 1 1101001101001,00010,000 1 10 100 1,000 10,000 Number of deaths and missing persons Number of completely destroyed houses Number of completely destroyed and half destroyed houses and houses with inundation above floor level Fig. 2. Relationship between the damage scale and news coverage numbers for two months after the West Japan Heavy Rain disaster. ally learned about them two or more days later [4]. Earthquake [4]. Figure 1 also shows the “half-life period for media This case study analyzed the West Japan Heavy Rain exposure of the disaster” [5]. This indicates the num- disaster to determine the relationship between the dam- ber of days subsequent to the disaster in which the num- age in each city, town, and village in the Hiroshima, ber of articles lowers by more than the half the “maxi- Okayama, and Ehime Prefectures as reported for a two- mum number of articles per day.” The half-life period month period after the heavy rain and the number of news thus indicates the persistence of social concern. The half- articles (i.e., the extent of media exposure) released in life period of media exposure was one week (i.e., seven that timeframe. In the surveyed areas of the Hiroshima, days) for both the Niigata-Chuetsu and Kumamoto Earth- Okayama, and Ehime Prefectures, the number of deaths quakes, while the half-life period of web media exposure and missing persons as of October 2018 was 114, 64, for the West Japan Heavy Rain disaster was 24 days. That and 29, respectively. These numbers were significantly is, it lasted about three times longer than coverage of ei- larger than those in other prefectures. The number of ther of the two earthquakes. After examining the half- news articles was then calculated. Here, an article was life period of media exposure, the author determined that counted as one if it contained the name of a city, town, no disaster coverage other than that concerning the Great or village (i.e., the name of an affected city, town, or vil- East Japan Earthquake had a half-life that exceeded one lage was presented in the article). Fig. 2 shows the re- week. Specifically, the half-life period for media exposure lationships between the number of news articles and the on the Great East Japan Earthquake lasted approximately number of deaths and missing persons (i.e., the number two months [5]. Thus, the West Japan Heavy Rain disas- of victims), the number of completely destroyed houses, ter attracted the second most significant amount of social the total number of completely and half-destroyed houses, concern in the last 15 years (Fig. 2). and houses with that were inundated with water above floor-level for each city, town, and village. These data were current as of September 6, 2018. Regression formula 4. Relationship Between the Damage Scale, Y = aX +b was created based on each scatterplot diagram Amount of News Coverage, and Amount of in Fig. 2, while the residual of the data from the straight Support line is shown in Fig. 3 for each city, town, and village. Two different damage scales were used. The first involved Sato et al. [5] showed that the extent of support from the amount of damage as calculated based on the num- areas other than those incurring damage significantly af- ber of deaths, number of completely destroyed houses, fected the amount of news coverage. For the Great East and other related factors. The second involved the rate Japan Earthquake, the amount of news coverage in each of damage as calculated based on the ratio of victims or area was highly correlated with the extent of available hu- the percentage of destroyed houses. In studies [4] and [6], man support. Even though there was significant human the extent of media exposure or the amount of available and material damage, some areas had relatively little hu- support was found to strongly correlate with the amount man support because of low media exposure. On the other of damage. We thus employed the amount of damage as hand, the amount of news coverage and extent of human an index for the damage scale. support concerning the Kumamoto Earthquake were pro- Figure 2 shows that a large number of news arti- portional to the scale of human and material damages in cles concerned Kurashiki City and Okayama City in the all cities, towns, and villages, while no significant discrep- Okayama Prefecture as well as Hiroshima City and Kure ancy was observed between the amount of news/support City in the Hiroshima Prefecture.