future internet

Communication Twitter-Based Safety Confirmation System for Disaster Situations

Keisuke Utsu 1,* , Mariko Abe 1, Shuji Nishikawa 2 and Osamu Uchida 3

1 Department of Communication and Network Engineering, School of Information and Telecommunication Engineering, Tokai University, Minato City, Tokyo 108-8619, Japan; [email protected] 2 Course of Information and Telecommunication Engineering, Graduate School of Information and Telecommunication Engineering, Tokai University, Minato City, Tokyo 108-8619, Japan; [email protected] 3 Department of Human and Information Science, School of Information Science and Technology, Tokai University, Hiratsuka City, Kanagawa 259-1292, Japan; [email protected] * Correspondence: [email protected]



Received: 6 November 2019; Accepted: 11 January 2020; Published: 16 January 2020


Abstract: In the aftermath of disastrous events in Japan, safety information and rescue requests, as well as emergency alerts and damage situations, have been shared on Twitter. However, even victims who are familiar with smartphones or similar devices and social media cannot easily share detailed information, such as the coordinates or address of their current location, which are essential components of safety information and rescue requests. Moreover, local governments and rescue experts have difficulty in gathering such tweets from Twitter. In this paper, we propose a novel system to enable the victims to share their safety information, make rescue requests, and enable quick information gathering for decision making by local government staff or rescue experts. The proposed system is a Twitter-based safety confirmation system named T-@npi. Using the proposed application, the users can easily submit their safety information and send rescue requests on Twitter. The users who want to confirm the safety information can check it quickly on Twitter or via this system. Furthermore, the registered safety information is displayed on an online map to support rescue and assistance activities by local governments and rescue experts.

Keywords: safety confirmation; disaster; Twitter; social media

1. Introduction Recently, social media have played an important information-sharing role during disaster and crisis events [1–3]. In particular, the social media application Twitter has gained traction in disaster situations [4–12]. On Twitter, users can post pictures and short messages (tweets) in 280 characters (140 Japanese characters) or less. Among the most important features of Twitter is the ease of distributing information from posters to followers. Many Twitter users posted tweets of disaster-related information during major emergency events such as the Haiti earthquake, severe hurricanes (Sandy, Harvey, Irma, and Maria), the Boston Marathon bombing, and typhoon Haiyan [7–11]. Many of these active tweets included hashtags of the disaster name, such as “#sandy,” “#hurricane,” “#haiyan,” and “#typhoonhaiyan” [12]. In Japan, large-scale natural disasters, such as earthquakes and floods, are frequent. After a disaster, many people try to confirm the safety of their family and friends, usually by fixed-line and cellphone calls [13]. However, the communication infrastructure in Japan is often disabled for long periods after a large-scale disaster. For example, the Great East Japan Earthquake of 11 March 2011 caused extensive damage to communication infrastructures. After the earthquake, many fixed-line

Future Internet 2020, 12, 14; doi:10.3390/fi12010014 www.mdpi.com/journal/futureinternet Future Internet 2020, 12, 14 2 of 16 and cellphone calls were disrupted. In many places, this situation persisted for a long time because the communication carriers took control of network traffic to prevent congestion. Immediately after the Great East Japan Earthquake in 2011 and the 2016 Kumamoto Earthquake, many people who were blocked from telephone communication by traffic congestion could access the Internet [14]. In this situation, Twitter was used for safety-information sharing, rescue requests, emergency alerts, and damage reports [15–17]. Similar situations occurred during recent disasters such as the 2017 Northern Kyusyu Heavy Rain Disaster and the 2018 Japan Floods [18]. Twitter has become an important tool for communicating safety information and rescue requests. To request a rescue on Twitter in Japan, the @TwitterLifeline account [19] suggests a rule as follows: Victims should use the hashtag #救助 (meaning #Rescue) and describe accurate and detailed • information, such as the requirements, pictures, address, and location on the tweet. When rescued, victims should report that they have been rescued and should immediately remove • the rescue-request tweet that was previously posted. This rule was posted as a tweet on 11 September 2015 and 10 July 2018. During the recent major flood events, many tweets clarified the rescue needs of their posters using rescue request hashtags such as #救助 (#Rescue) and #救助要請 (meaning #Rescue_request). The effectiveness of tweets with these hashtags has been discussed [20–22]. To accomplish rescue activities based on the rescue request tweets in future disasters, we require a system that can effectively share such rescue requests as well as safety information. The above background highlights the need for a novel system through which victims can share their safety information, make rescue requests, and enable quick information gathering for decision making by local government staff or rescue experts. In this paper, we propose a Twitter-based safety confirmation system (T-@npi), a web application that can be accessed by any web browser or device connected to the Internet [23]. The name T-@npi derives from the Japanese word “安否” (pronounced anpi), meaning the degree of a person’s safety. This paper introduces the operation of T-@npi and a preliminary operational test of the system. The remainder of the paper is organized into Section2, which describes the related services and studies, and Section3, which explains the proposed T-@npi system and performs an operational test of safety-information registration by the system. The paper concludes with Section4.

2. Related Studies and Services

2.1. Safety Confirmation Services in Disaster Situations The safety of victims must be confirmed immediately after a large-scale natural disaster. Various services are provided for confirming individual safeties. Google Person Finder [24] is a web service that helps people to reconnect after a disaster. The site was launched in 2010 and was used after the Great East Japan Earthquake of 2011, the 2011 Christchurch earthquake, the 2010 Haiti earthquake, the 2013 Boston Marathon Bombing, and other disasters. In the aftermath of the Great East Japan Earthquake, 670,000 people were recorded on the service. Restoring Family Links [25] and Safe & Well [26] also provide online systems for sharing safeties and missing-persons information. Safety confirmation services in Japan include the Disaster Emergency Message Dial (171) [27] and the Disaster Emergency Message Board (web171) [28]. Communication carriers provide these services as alternative channels when the network is congested by a large number of safety confirmation phone calls. After the Great East Japan Earthquake, both 171 and web171 were not used by many people [13]. Sekiya and Fukasawa analyzed the reasons why few people use the systems for confirming safeties in disaster situations [29]. Examples of such reasons include that the systems are not used at ordinary times, and these systems are difficult to use. To sum up, to gain the maximum advantage from these services, users checking for safety information must use them actively, and victims who have registered their information must use them frequently. Hatayama reviewed the safety confirmation systems including 171 and web171 [30]. This article noted an importance of immediate confirmations for people needed to be rescued and such systems cannot contribute to the rescue activities for survivors. Future Internet 2020, 12, 14 3 of 16

Considering that point, the above systems can be useful only to deliver the information about safe people from the disaster affected areas to the outside of the area. The utilization of social media services is an effective solution for confirming safety information because many people use them at ordinary times and are familiar to them. Some social networking services (SNSs) can provide their own safety confirmation services. An example is Facebook, the most popular SNS worldwide [31]. In such a system, users in a disaster zone are expected to confirm their safety by reply, and the response is sent to the users’ friends on their respective timelines. A popular communication tool in Asia is LINE (https://line.me/en/), which is more suitable than Facebook for confirming the safety of users to close friends. Users of the LINE application are sent requests for their safety, and their responses are displayed on their timelines [32]. On Twitter, many tweets were posted during the recent disasters in Japan. However, Twitter itself does not provide any functions to facilitate sharing the safety information.

2.2. Rescue Request Tweets Posted during Large-scale Disasters in Japan Certain studies have reported the use of social media posts as emergency-dispatch platforms outside Japan [33,34]. However, as of yet, no official rules or procedures have been established to respond to rescue request posts in Japan. A large number of tweets, including safety information and rescue requests, were posted on Twitter during the Great East Japan Earthquake in 2011. Regarding the earthquake, Neubig et al. developed an extraction system using natural language processing (NLP) for disaster-response situations to extract tweets containing safety information [35]. Aida et al. developed a website which extracted the rescue request information [36]. The website automatically listed similar statements by text filtering to extract the rescue requests from Twitter. This article reported that the website could contribute to execute emergency calls. As mentioned in Section1, tweets with rescue request hashtags such as # 救助 (#Rescue) and #救 助要請 (meaning #Rescue_request) were posted in the recent major flood events. The use of such hashtags in tweets posted during the 2017 Northern Kyushu Flood has been analyzed in multiple studies [20–22]. Sato indicated that not many tweets with such hashtags included detailed information on the location of the victims, the current state of damage and injuries, or the number of injured victims, which are necessary to achieve rescue. In fact, only a few rescues were accomplished based on the rescue request tweets [21]. On the other hand, Nishikawa et al. collected and analyzed the tweets with rescue request hashtags posted during the 2018 Japan floods [22]. The result indicated that the tweets requesting rescues included area names, landmark names, or street numbers, which could prove to be useful when specifying the place where the rescue was needed. However, in both two flood events, many tweets did not include the information directly related to rescue requests. Therefore, we have difficulty in extracting tweets truly requesting rescues. Song and Fujishiro studied a method to efficiently extract the tweets requesting rescues from the dataset of tweets with hashtag #rescue posted the 2018 Japan Floods [37]. It performed with a relatively high accuracy rate of 64.7%. To increase the accuracy of extracting the tweets requesting rescues, the victims are required to provide accurately detailed information. However, even people who are familiar with smartphones or similar devices and social media cannot easily provide detailed information. Therefore, a system is required to facilitate sharing the rescue request tweets.

2.3. Facilitation of Sharing Disaster-related Information Geographic information systems (GIS) have also been utilized for disaster response [38,39]. One GIS-based framework extracts credible posts on Twitter (tweets) with geographic information in the context of disaster-situation awareness [40]. The integration of social media data and GIS applications has become important for disaster prevention and mitigation. Uchida et al. proposed a web application called the disaster information tweeting and mapping system (DITS/DIMS) [41,42]. In this system, smartphone users can easily send Future Internet 2020, 12, 14 4 of 16 their disaster-related information through Twitter, and the registered information is mapped on an online map. This system allows local government staff to gather information and share it with citizens. Educational workshops on disaster prevention using this application have also been organized [43]. Similarly, Uchida et al. also proposed a chatbot application on LINE for sharing disaster-related information has been proposed [44]. The application enables LINE users to send the information with easy operations and share it on Twitter. These studies commonly aim to help and encourage users to share the disaster-related information actively. By a similar approach in those studies, we propose a system to facilitate the sharing of the safety information and rescue requests.

3. Proposed Application T-@npi We propose a Twitter-based safety confirmation system (T-@npi) that enables disaster victims to share their safety information and rescue requests, enabling quick access to the disaster information for decision making by local government staff or rescue experts.

3.1. Requirements The requirements of the proposed system are listed below:

1. Social media adoption: The safety information of victims should be confirmed as quickly as possible after a disaster. The proposed system requires the use of social media such as Twitter for efficient information sharing. 2. Facilitation of sending rescue requests: Victims needing to be rescued must provide detailed information and the coordinates of their location on a tweet, as instructed by @TwitterLifeline [19]. However, even people who are familiar with smartphones or similar devices and social media cannot easily provide such detailed information. Thus, the proposed system must be equipped with a function that sends rescue requests via an easy operation. 3. Renewal and deletion of old information: As instructed in [19], users who sent a rescue request should remove the rescue-request tweet after the rescue, and then update their status (rescue or self-resolution of the emergency). To prevent the spreading of old information, the proposed system requires a reregistration function by which users can delete the previously posted rescue request and post the new information. 4. Encouraging mutual and public help: Self-help, mutual help, and public help are important for disaster prevention and mitigation. The existing services can share a user’s safety information with families, relatives, and friends (i.e., self-help), but lack functions for sending and sharing rescue requests by victims in trouble (i.e., mutual and public help). To facilitate rescue and support activities, the safety information and rescue requests should be shared with local governments and rescue experts (enabling public help), and with neighbors of the victims. The needs of a large-scale disaster may exceed the capacity of local governments, firefighter rescue parties, and police officers, necessitating the assistance of neighbors (i.e., mutual help.) Thus, the proposed system must support both mutual and public help. 5. GIS integration: The registered safety information and rescue requests must be mapped on an online map for decision making decisions by local governments and rescue experts.

3.2. Twitter Adoption In the proposed application, Twitter was adopted for the following reasons:

Twitter is a widely used service. Consequently, most users are conversant with it, and thus, they • can use the proposed application easily. Moreover, since users do not often use existing services such as 171 and web171, they are not familiar with using them, and this has been a bottleneck in regard to the acceptance of these applications. The application proposed in this paper addresses this problem. Future Internet 2020, 12, 14 5 of 16

Although Twitter has been previously used for rescue requests and other information sharing, • rescue requests are not supported by the existing services such as 171 and web171. Therefore, these services are limited to the communication of safety information only. The proposed system overcomes this limitation. The proposed system is inexpensive. As information is exchanged only on Twitter, the proposed • Futuresystem Internet requires 2020, 12 no, 14 large-scale hardware. 5 of 16 The system administrators and operators do not need to maintain their individual information • • because The proposed all users system are uniquely is inexpensive. identified As informat by theirion respective is exchanged Twitter only IDs. on Twitter, the proposed system requires no large-scale hardware. Unlike Facebook and LINE, Twitter is an open social media, meaning that the proposed application • • The system administrators and operators do not need to maintain their individual information supports mutual and public help. because all users are uniquely identified by their respective Twitter IDs. • 3.3. AssumedUnlike Users Facebook and Devices and LINE, Twitter is an open social media, meaning that the proposed application supports mutual and public help. The application is intended for three types of users. 3.3. Assumed Users and Devices Sending user: A user who posts his or her safety information. • The application is intended for three types of users. Confirming user: A user who checks the safety information post of another individual. The confirming • •user Sending is expected user: to A “follow”user who the posts sending his or her user safety on Twitter. information. • SupportingConfirming user: user: A user A user such who as a localchecks government the safety information staff member post who of checks another the individual. safety information The • confirming user is expected to “follow” the sending user on Twitter. of a disaster-stricken area. • Supporting user: A user such as a local government staff member who checks the safety Userinformation devices are of assumed a disaster-stricken to be smartphones, area. tablet PCs, or general PCs. User devices are assumed to be smartphones, tablet PCs, or general PCs. 3.4. System Outline 3.4. System Outline The programs of the system are written in PHP (Hypertext PreProcessor), JavaScript, and MySQL database.The All programs programs of arethe deployedsystem are on written an internet in PHP server. (Hypertext The PHPPreProcessor), scripts call JavaScript, the Twitter and API MySQL database. All programs are deployed on an internet server. The PHP scripts call the Twitter (application programming interface) [45] to post and search for information on Twitter. API (application programming interface) [45] to post and search for information on Twitter. The system is outlined in Figure1. Figure1a explains the operation of registering and sending The system is outlined in Figure 1. Figure 1a explains the operation of registering and sending the safetythe safety information. information. Sending Sending users users accessaccess th thee T-@npi T-@npi system system through through a web a web browser browser and andenter enter theirtheir safety safety information information on on the the registrationregistration page. page. Th Thisis information information is simultaneously is simultaneously recorded recorded in the in the databasedatabase of of the the T-@npi T-@npi system system and and tweeted tweeted on the on us theer’s user’sTwitter Twitter account. account. If the user If tweets the user a rescue tweets a rescuerequest, request, the the information information is email is emaileded to a to supporting a supporting user. user. The Thee-mail e-mail notification notification is an is additional an additional channelchannel that that improves improves the the reachability reachability of of thethe rescuerescue request to to supporting supporting users. users. When When the sending the sending useruser reregisters reregisters the the safety safety information, information, thethe databasedatabase record record is is renewed, renewed, and and the the previously previously posted posted tweettweet is deleted. is deleted. If the If reregistering the reregistering sender sender has previously has previously requested requested a rescue, a therescue, renewed the renewed information is alsoinformation emailed is to also the emailed supporting to the user. supporting Figure user.1b explains Figure 1b the explains operation the operation of confirming of confirming the safety the safety information. The confirming users who follow the sending user can find the safety information. The confirming users who follow the sending user can find the safety information on the information on the sending user’s Twitter timeline. If needed, the confirming user can then distribute sending user’s Twitter timeline. If needed, the confirming user can then distribute this information on this information on Twitter. The supporting users can determine the status of their supported disaster Twitter.area Theand supportingview a list or usersmap of can the determinesafety informat theion status submitted of their by supported the sending disaster users from area the and system’s view a list or mapdatabase. of the safety information submitted by the sending users from the system’s database.

(a) Sending the safety information.

Figure 1. Cont.

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(b) Confirming the safety information. (b) Confirming the safety information. Figure 1. Outline of the proposed system. FigureFigure 1. 1.Outline Outline of the proposed proposed system. system. 3.5. System Operation and Screens 3.5. System3.5. System Operation Operation and and Screens Screens

3.5.1.3.5.1. Index Index Page Page FigureFigure2 2 shows shows 2 shows thethe the indexindex index pagepage page thatthat that appearsappears appears whenwhen aa useruser first firstfirst accesses accessesaccesses the thethe application applicationapplication via viaavia web aa web web browser.browser. TheThe userThe user selectsuser selects theselects desired thethe operationdesireddesired operation byoperation pressing byby one pressing ofpressing three buttons: oneone of of “three自 分three のbuttons:安 否buttons:情報 を 自分の安否情報を発信・修正する 発“自分の安否情報を発信・修正する信・“ 修正する (Register/reregister your(Register/reregister safety(Register/reregister information),” “your他yourの 人 のsafety安safety否 情報 information),”を検information),”索する (Find “他の人の安否情報を検索する (Find somebody’s safety information),” and “安否情報の一覧表示 somebody’s“他の人の安否情報を検索する safety information),” (Find and “somebody’s安否情報の一 safety覧表示 information),”(List the registered and “ safety安否情報の一覧表示 information)”. (List (Listthe registeredthe registered safety safety information).” information).”

Figure 2. Appearance and operation of the index page. Figure 2. Appearance and operation of the index page. 3.5.2. Registration of SafetyFigure Information 2. Appearance and operation of the index page. 3.5.2. RegistrationFigure 3 shows of Safety the flow Information of registering and reregistering the safety information. A first-time 3.5.2.sending Registration user registers of Safety the Information information by pressing the “Register/reregister your safety information” buttonFigure 3on shows the index the flowpage of(Figure registering 2). After and a reregisteringTwitter authentication, the safety the information. registration A page first-time shown sending in Figure 3 shows the flow of registering and reregistering the safety information. A first-time userFigure registers 4 appears the information (Figure 3a). byThe pressing registration the page “Register displays/reregister the items your to be safetyprovided information” by the sending button sending user registers the information by pressing the “Register/reregister your safety information” on theuser. index page (Figure2). After a Twitter authentication, the registration page shown in Figure4 button on the index page (Figure 2). After a Twitter authentication, the registration page shown in appears• (Figure3a). The registration page displays the items to be provided by the sending user. Figure 4 appearsSelection (Figureof rescue 3a). request The registration(item (1) in Figurepage displays 4): The rescue-request the items to beitem provided offers two by options,the sending “YES” (a rescue is needed) or “NO” (no rescue is needed). If the sender selects “YES,” the tweet user.Selection of rescue request (item (1) in Figure4): The rescue-request item o ffers two options, “YES” • to be posted includes the hashtag #救助 (#Rescue). If the user selects “NO,” the tweet to be posted (a rescue is needed) or “NO” (no rescue is needed). If the sender selects “YES,” the tweet to be • Selectionincludes of “Rescuerescue requestis not needed.” (item (1) in Figure 4): The rescue-request item offers two options, posted includes the hashtag #救助 (#Rescue). If the user selects “NO,” the tweet to be posted “YES” (a rescue is needed) or “NO” (no rescue is needed). If the sender selects “YES,” the tweet includesto be posted “Rescue includes is not the needed”. hashtag #救助 (#Rescue). If the user selects “NO,” the tweet to be posted includes “Rescue is not needed.”

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Selection of safety status (item (2) in Figure4): Sending users can select one or more checkboxes to • Futurecommunicate Internet 2020, their12, 14 safety status: “無事です (Fine),” “被害があります (Injured/damaged),”7 of 16 “自 宅 にいます 避難所にいます • Selection(At of home),” safety status and (item “ (2) in Figure 4):(At Sending an evacuation users can select center).” one or The more status checkboxes choices are basedto communicate on those of web171 their safety [28]. status: “無事です (Fine),” “被害があります (Injured/damaged),” Additional“自宅にいます comment (At home),” (item (3) and in “避難所にいます Figure4): The (At sending an evacuation user can center).” enter a The comment status choices of up to • 40 characters.are based on those of web171 [28]. •Current Additional location comment of the user (item (item (3) in (4) Figure in Figure 4): The4): Thesending location user informationcan enter a comment (latitude of and up longitude to 40 • information)characters. of the sending user is obtained by global positioning and geolocation systems and • is calledCurrent by location JavaScript. of the This user information (item (4) isin transformedFigure 4): The into location an address information by a reverse (latitude geocoding and servicelongitude [46]. Ininformation) the current of version the sending of the user proposed is obtained system, by global address positioning transformation and geolocation is available systems and is called by JavaScript. This information is transformed into an address by a reverse only in Japan. When a user selects the “はい (Yes)” button for the query “現在地も合わせて送 geocoding service [46]. In the current version of the proposed system, address transformation is 信しますか (Do you send your current location information together?),” the user’s address is available only in Japan. When a user selects the “はい (Yes)” button for the query sent“現在地も合わせて送信しますか together with the safety information. (Do you Otherwise,send your current the address location is information registered astogether?),” “N/A.” If the sendingthe user’s user’s address device cannotis sent detecttogether the with location the safety or the userinformation. does not Otherwise, want to provide the address the location is information,registered theas “N/A.” address If the is also sending registered user’s asdevice “N/ A”.cannot detect the location or the user does not want to provide the location information, the address is also registered as “N/A.” Once the “Submit” button is pressed, the relevant information is recorded on the system, and a tweet is postedOnce the on “Submit” Twitter (Figurebutton 3isb). pressed, The information the relevant of information a rescue request is recorded is notified on the to system, the supporting and a tweet is posted on Twitter (Figure 3b). The information of a rescue request is notified to the user by e-mail. The confirming user following the sending user can check the sender’s tweets on Twitter. supporting user by e-mail. The confirming user following the sending user can check the sender’s Figure5 is an example tweet of the safety information when the sending user needs a rescue and tweets on Twitter. Figure 5 is an example tweet of the safety information when the sending user needs providesa rescue his and/her provides current his/her location current information. location information. Figure6 is an Figure example 6 is an tweet example of the tweet safety of the information safety providedinformation by a user provided not needing by a user rescue, not needing and who rescue, does and not who provide does not the provide current the location. current location.

Press the button “Register/reregister your safety info”

Log in to Twitter account

N (reregistration) Was rescue requested N 1st registration? in last registration?

(a) YY(c)

Enter safety information Check last record at Confirmation page (Figure 7), at Registration page (Figure 4) which asks whether rescue is still needed or not

N N Is rescue requested? Is rescue still needed?

(b) Y (d) Y

• Record to T-@npi server • Renew record on T-@npi server • Record to T-@npi server • Post tweet which incudes #Rescue • Remove last tweet • Remove last tweet • Notify the supporting user by an e- • Post tweet which incudes #Rescue • Post tweet mail • Notify the supporting user by an e-mail

(e) • Post tweet • Renew record on T-@npi server • Record to T-@npi server • Remove last tweet • Post tweet including “Already rescued, no longer needed” • Notify the supporting user by an e-mail FigureFigure 3. 3.Flow Flow of of registering registering and reregistering the the safety safety information. information.

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FigureFigure 4. 4.Registration Registration page page of of safety safety informationinformation presented to to the the sending sending user. user. Figure 4. Registration page of safety information presented to the sending user.

FigureFigure 5. Example5. Example tweet tweet of of the the safety safety information information postedposted byby a user needing needing re rescuescue from from the the specified specified currentFigurecurrent 5. location. Example location. tweet of the safety information posted by a user needing rescue from the specified current location.

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FutureFuture Internet Internet 2020 2020, ,12 12, ,14 14 99 of of 16 16

FigureFigureFigure 6. Example 6. 6. Example Example tweet tweet tweet of of of the the the safety safety safety informationinformation information posted posted by by a a safe safe user user user from from from an an an unspecified unspecified unspecified location. location. location. 3.5.3. Reregistration of Safety Information 3.5.3.3.5.3. Reregistration Reregistration of of Safety Safety Information Information RegisteredRegisteredRegistered sending sendingsending users usersusers can cancan renew renewrenew their theirtheir safety safetysafety information informationinformation on on theon thethe system systemsystem database, database,database, remove removeremove their previoustheirtheir previousprevious tweets, andtweets,tweets, repost andand their repostrepost renewed theirtheir renewed statusesrenewed on ststatusesatuses Twitter. onon To Twitter.Twitter. reregister ToTo theirreregisterreregister safety theirtheir information, safetysafety usersinformation,information, press the “Register usersusers presspress/reregister thethe “Register/reregister“Register/reregister your safety information” youryour safetysafety button information”information” on the index buttonbutton page onon shown thethe indexindex in Figure pagepage 2. shownshownWhen in in usersFigure Figure who 2. 2. previously tweeted a rescue request need to reregister their updated information, they areWhenWhen presented usersusers withwhowho thepreviouslypreviously page shown tweetedtweeted in Figure aa rescuerescue7, which requestrequest asks needneed whether toto reregisterreregister a rescue their istheir still updatedupdated required (Figureinformation,information,3c). If the they they “ はいare are presented presented(Yes)” option with with the the is pressed,page page shown shown the in pagein Figure Figure moves 7, 7, which which to the asks asks registration whether whether a a pagerescue rescue shown is is still still in Figurerequiredrequired4 (without (Figure(Figure asking 3c).3c). IfIf the thethe necessity ““はいはい (Yes)”(Yes)” of the optionoption rescue isis request). pressed,pressed, the Thethe pagepage sending movesmoves user toto then thethe registrationregistration enters the current pagepage safetyshownshown information in in Figure Figure 4 4 on (without (without this page. asking asking When the the necessity necessity the “Submit” of of the the buttonrescuerescue request). request). is pressed, The The the sending sending entered user user information then then enters enters is recordedthethe currentcurrent on the safetysafety system, informationinformation the previously onon thisthis posted page.page. tweet WhWhenen is thethe deleted, “Submit”“Submit” a renewed buttonbutton tweet isis pressed,pressed, is posted thethe on enteredentered Twitter, andinformationinformation the information isis recordedrecorded is emailed onon thethe to system, thesystem, supporting thethe previousprevious userly (Figurely postedposted3d). tweettweet If the isis sending deleted,deleted, useraa renewedrenewed no longer tweettweet needs isis a rescue,postedposted he onon or Twitter,Twitter, she should andand the pressthe informationinformation the “いいえ isis emailed(No)”emailed button toto thethe on supportingsupporting the page inuseruser Figure (Figure(Figure7. As 3d).3d). in If theIf thethe “YES” sendingsending case, user no longer needs a rescue, he or she should press the “いいえ (No)” button on the page in Figure theuser user no is longer directed needs to the a rescue, registration he or she page should shown press in Figurethe “いいえ4. When (No)” entering button the on current the page information, in Figure 7. As in the “YES” case, the user is directed to the registration page shown in Figure 4. When entering the7. rescue As in the requirement “YES” case, of the the user tweet is directed is described to the registration as “救助された page、 shown不要になっ in Figure,” meaning4. When entering “Already the current information, the rescue requirement of the tweet is described as “救助された、不要にな救助された、不要にな rescuedthe current/no longer information, needed” the (Figure rescue3 e).requ Again,irement the of updated the tweet information is described is as emailed “ to the supporting っっ,” meaning “Already rescued/no longer needed” (Figure 3e). Again, the updated information is user.,” Figure meaning8 shows “Already an example rescued/no of a tweetlonger in needed” this case. (Figure 3e). Again, the updated information is emailedemailed to to the the supporting supporting user. user. Figure Figure 8 8 sh showsows an an example example of of a a tweet tweet in in this this case. case.

FigureFigureFigure 7. 7. Page7. Page Page for for for confirming confirming confirming whether whether whether aa a sendingsending sending useruser who who previously previously requested requested requested a a arescuerescue rescue still still still needs needs needs thethethe rescue. rescue. rescue.

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Figure 8. Example of a safety information tweet indicating that the sending user no longer needs a Figure 8. Example of a safety information tweet indicating that the sending user no longer needs rescue. Figurea rescue. 8. Example of a safety information tweet indicating that the sending user no longer needs a rescue. WhenWhen a asending sending user user who who previously previously register registereded aa “No“No rescuerescue needed”needed” post post reregisters reregisters the the information,information,When thea thesending page page shown shownuser who in FigureFigure previously9 9appears. appears. register This Thised page pagea “No asks asks whetherrescue whether needed” the userthe postuser wishes reregisterswishes to renew to renew thethe はい theinformation,previously previously registered the registered page safetyshown safety information. in Figure information. 9 appears. If the userIf This the presses page user “asks はいpresses whether(Yes, “ reregister the user (Yes, the wishes information),” reregister to renew the information),”thethe pagepreviously is redirected the registeredpage to is theredirected registrationsafety information.to the page registration shown If inthe Figurepage user shown4 .presses When in theFigure“ はい information 4. When(Yes, on reregisterthe this information page the is oninformation),”reregistered, this page is thereregistered, the former page is record redirected the onformer the to database the record registration ison renewed, the pagedatabase andshown the is inrenewed, former Figure tweet 4. andWhen is the deleted. the former information tweet is deleted.on this page is reregistered, the former record on the database is renewed, and the former tweet is deleted.

FigureFigureFigure 9. 9. 9.Page PagePage that that that requests requests requests whether whether whether thethe the sending sending user user wi wisheswishesshes to toto reregister reregisterreregister the the safety safety information. information. 3.5.4. Confirmation of Safety Information 3.5.4.3.5.4. Confirmation Confirmation of of Safety Safety Information Information As shown in Figures5 and6, a confirming user can check the safety information of his /her AsAs shown shown in in Figures Figures 5 5 and and 6,6, aa confirmingconfirming user cancan checkcheck the the safety safety information information of ofhis/her his/her following people on the Twitter timeline. In addition, the confirming user can check the safety followingfollowing people people on on the the Twitter Twitter timeline.timeline. In addition,tion, thethe confirmingconfirming user user can can check check the the safety safety informationinformation by enteringentering thethe TwitterTwitter IDID of of the the sending sending user user he he/she/she wants wants to to find find on on the the page page shown shown in informationFigure 10. by entering the Twitter ID of the sending user he/she wants to find on the page shown in inFigure Figure 10. 10.

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FigureFigureFigureFigure 10. Confirmation 10.10. 10. ConfirmationConfirmation Confirmation page. page.page. page. Figure 10. Confirmation page. 3.5.5.3.5.5.3.5.5.3.5.5. List ListList andList andand Mapand MapMap Mapview viewview view for forSupportingfor for SupportingSupporting SupportingFigure Users 10.UsersUsers Users Confirmation page. 3.5.5. List and Map view for Supporting Users 3.5.5.The ListTheThe proposedThe and proposedproposed proposed Map system view systemsystem system for displays Supporting displaysdisplays displays the thethesafety theUsers safetysafety safety inform informinform informationationationation recorded recordedrecorded recorded on theonon on thethedatabase the databasedatabase database in both inin in bothboth bothtabular tabulartabular tabular andandand onlineandThe onlineonline online proposed map mapmap map(Yahoo! system(Yahoo!(Yahoo! (Yahoo! Japan displays JapanJapan Japan map) map)map) themap) formats. safety formats.formats. formats. informationIn thisInIn In this this way,this way,way, way, recordedsupporting supportingsupporting supporting on users the usersusers databaseusers can can can collectcan incollectcollect collect both the the tabularthe safetythe safetysafety safety The proposed system displays the safety information recorded on the database in both tabular informationandinformationinformationinformation online and map andand supportand (Yahoo! supportsupport support victims. Japan victims.victims. victims. map)Figure FigureFigure Figure formats. 11 shows 1111 11 showsshows shows In the this themapthe the way, mapmap mapview supporting viewview view of a of ofrescue of aa a rescuerescue rescue users request requestrequest canrequest on collect this onon on this thispage. this the page.page. safetypage. The TheThe The and online map (Yahoo! Japan map) formats. In this way, supporting users can collect the safety supportinginformationsupportingsupportingsupporting user and user user usercan support can canfiltercan filter filterfilter victims.the the theinformationthe information information Figureinformation 11 by shows bylocation byby location locationlocation the mapand/or and/or and/orand/or view rescue-request ofrescue-request rescue-requestrescue-request a rescue requestselections, selections, selections,selections, on thissort sort page.sortsortthe the thethe information and support victims. Figure 11 shows the map view of a rescue request on this page. The informationTheinformationinformationinformation supporting on the onon useron thetable,the thecan table,table, table, and filter andand viewand the viewview view it. information The it.it. it. TheThe mappingThe mappingmapping mapping by locationis accomplished isis is accomplishedaccomplished accomplished and/or rescue-request on Yah onon on YahYahoo! Yah oo!Japanoo!oo! selections,JapanJapan Japan online onlineonline online map sort mapmap mapvia the viavia via supporting user can filter the information by location and/or rescue-request selections, sort the theinformation thetheJavaScriptthe JavaScriptJavaScript JavaScript on Map the MapMap table,MapAPI APIAPI [47].API and [47].[47]. view[47].The TheThe mapThe it. Themapmap mapdisplays mapping displaysdisplays displays only is onlyonly accomplished onlythe thethesafety the safetysafety safety information on informationinformation information Yahoo! that Japan thatthat isthat onlineaccompanied isis is accompaniedaccompanied accompanied map via by the byby by information on the table, and view it. The mapping is accomplished on Yahoo! Japan online map via locationJavaScriptlocationlocationlocation information. Map information. information.information. API [47 Table]. TheTable TableTable 1 map provides 1 1 1 displaysprovides providesprovides the only the themeaningsthe the meanings meaningsmeanings safety of information theof ofof the theiconthe icon icon iconmarkers that markers markersmarkers is accompanied on onthe onon the themapthe map bymap mapand location and and andthe the thethe the JavaScript Map API [47]. The map displays only the safety information that is accompanied by backgroundinformation.backgroundbackgroundbackground colors Table colorscolors colors 1in provides the inin in thethe list.the thelist. list. Whenlist. meanings WhenWhen When users usersusers users ofclick the clickclick clickon icon anonon on markers icon,anan an icon,icon, icon, the on thethe information thethe informationinformation mapinformation and related the relatedrelated backgroundrelated to that toto to thatthat iconthat colors iconicon iconis isis is location information. Table 1 provides the meanings of the icon markers on the map and the displayedin thedisplayeddisplayeddisplayed list. in When a in inballoon in aa a balloon usersballoon balloon (Figure click (Figure(Figure (Figure on 12). an 12). 12).The 12). icon, TheThe tableThe the tabletable table and information andand mapand mapmap mapprovide relatedprovideprovide provide the to thesequencethe the that sequencesequence sequence icon number is displayednumbernumber number on the onon on in thedatabase,the athe balloon database,database, database, background colors in the list. When users click on an icon, the information related to that icon is the(Figure thetheTwitterthe TwitterTwitter 12Twitter). ID, The ID,ID, theID, table thethe registrationthe andregistrationregistration registration map date provide datedate dateand andand thetimeand sequencetimetime timeof theofof of thethe information,the number information,information, information, on thethe the database,the rescuethe rescuerescue rescue necessity, the necessity,necessity, necessity, Twitter the theID,the safetythe safety thesafety safety displayed in a balloon (Figure 12). The table and map provide the sequence number on the database, information,registrationinformation,information,information, datethe thelocationthe andthe locationlocation location time of of the ofof theof theinformationthe the information, informationinformation information when the whenwhen when rescueregistered, registered,registered, registered, necessity, and andand aand the comment. aa safetya comment.comment. comment. information, The TheThe rescueThe rescuerescue rescue necessity the necessitynecessity locationnecessity is isis is the Twitter ID, the registration date and time of the information, the rescue necessity, the safety oneof theone oneofone “ information of必要of of ““ 必要“必要 必要(needed),” (needed),”(needed),” (needed),” when “不要 registered, ““ 不要“不要 不要 (not (not (not needed),” (not and needed),”needed),” needed),” a comment. or “ oror解決 or ““ 解決“解決 The 解決(no (no rescue(nolonger (no longerlonger longer necessityneeded).” needed).”needed).” needed).” is one of “必要 (needed),” information, the location of the information when registered, and a comment. The rescue necessity is “不要 (not needed),” or “解決 (no longer needed)”. one of “必要 (needed),” “不要 Table (notTableTable Tableneeded),” 1. Descriptions 1.1. 1. DescriptionsDescriptions Descriptions or “ 解決of the ofof (noof listthethe the longer andlistlist list andandmap. and needed).” map.map. map. Table 1. Descriptions of the list and map. LocationLocationLocationLocation Submitted SubmittedSubmitted Submitted Table 1. Descriptions Yes of Yes Yes Yesthe list and map. No NoNoNo RescueLocationRescueRescueRescue needed needed Submittedneeded needed Yes Yes Yes Yes No/NoNo/NoNo/NoNo/No longer Yes longerlonger longer No NolongerNoNo longerlonger longer No No No No No Any Any Any Any Location Submitted Yes No Injured/damagedInjured/damagedInjured/damagedInjured/damagedRescue neededchecked checkedchecked checked Any Any Any Any Yes No Yes/No Yes Yes Yes longer No No No No longer No No No No No Any Any Any Any Any Rescue needed Yes No/No longer No longer No Any BackgroundBackgroundBackgroundBackground color colorcolor color on the onon on thethe the Injured/damagedInjured/damaged checked checked Any Any Yes Yes No No No No Any Any tabletabletabletable entry entryentry entry Background color color on on the the table entry Not NotNot Not IconIcontableIcon IcononIcon the on onentry on themapthe thethe mapmap map map Not displayed displayeddisplayeddisplayeddisplayed Not Icon on the map displayed

Future Internet 2020, 12, 14 12 of 16 Future Internet 2020, 12, 14 12 of 16

Figure 11. List and map view page for the supporting users. Figure 11. List and map view page for the supporting users.

Future Internet 2020, 12, 14 13 of 16 Future Internet 2020, 12, 14 13 of 16

Figure 12. Safety information displayed on the list and map view page for the supporting users. Figure 12. Safety information displayed on the list and map view page for the supporting users. 3.6. Operational Test for Registration of Safety Information 3.6. Operational Test for Registration of Safety Information To verify the submission of safety information by users, an operational test was conducted from OctoberTo verify 30 to November the submission 20 of 2018.of safety The information experimental by participants users, an operational (42 in total) test were was 17 conducted students fromfrom theOctober School 30 ofto InformationNovember 20 and of 2018. Telecommunication The experimental Engineering participants (IT) (42 and in 25total) students were 17 from students the School from ofthe Business School of Administration Information and (BA). Telecommunication All students were En recruitedgineering from (IT) Tokaiand 25 University students from (Tokyo, the Japan).School Aof singleBusiness account Administration created for this(BA). test All was students shared were among recruited all participants. from Tokai Only University one participant (Tokyo, failed Japan). to submitA single their account safety created information, for this seemingly test was shared because among they did all notparticipants. correctly enableOnly one the participant location function failed ofto hissubmit smartphone. their safety information, seemingly because they did not correctly enable the location functionAfter of completion, his smartphone. the operational test was reviewed in a group discussion. None of the IT participantsAfter completion, reported diffi theculty operational with operating test was the system. reviewed Some in participantsa group discussion. opined that None more of detailed the IT informationparticipants couldreported be provided difficulty by with offering operating more functions the system. and answer Some options.participants In contrast, opined some that ofmore the BAdetailed participants information considered could thatbe provided the system by should offering be more simplified. functions The and differences answer in options. opinions In appeared contrast, tosome depend of the on BA the skillsparticipants of the smartphone considered operations. that the system The skills should problem be simplified. could be solved The differences by providing in twoopinions types appeared of registration to depend pages: on easy the skills mode of and the advanced smartphone mode. operations. The skills problem could be solvedMoreover, by providing the opinions two types and of contentious registration aspects pages: of easy the systemmode and were advanced obtained mode. from a questionnaire allocatedMoreover, to each the participant. opinions Representative and contentious comments aspects from of the the participants system were are shownobtained below. from a questionnaire allocated to each participant. Representative comments from the participants are shownIt would below. be useful if I could check people who have found my information. (IT) • The web application (accessed by web browsers) is time-consuming compared with a native •• It would be useful if I could check people who have found my information. (IT) application. This should be improved. (IT) • The web application (accessed by web browsers) is time-consuming compared with a native To popularize the system, the application should collaborate with other popular applications used • application. This should be improved. (IT) • inTo ordinary popularize times. the (BA)system, the application should collaborate with other popular applications The system should additionally collaborate with SNSs other than Twitter. (BA) • used in ordinary times. (BA) • The application may be abused because we can post anonymously. (BA) • The system should additionally collaborate with SNSs other than Twitter. (BA) • The application may be abused because we can post anonymously. (BA) The above comments will guide the improvements of the proposed system. The above comments will guide the improvements of the proposed system. 4. Conclusions 4. Conclusions During recent large-scale natural disasters in Japan, Twitter is used to share the safety information and rescueDuring request. recent It large-scale is important natural to confirm disasters people neededin Japan, to beTwitter rescued is quickly. used to Thus, share to accomplishthe safety theinformation rescue activities and rescue based request. on the tweets It is important requesting to rescues, confirm the people victims needed must provideto be rescued detailed quickly. information Thus, suchto accomplish as the coordinates the rescue or activities address ofbased their on current the tw location,eets requesting which arerescues, essential the componentsvictims must ofprovide safety informationdetailed information and rescue such requests. as the coordinates Moreover, the or localaddress governments of their current and rescue location, experts which need are toessential have a solutioncomponents to quickly of safety gather information such tweets and from rescue Twitter. requests. In this Moreover, paper, we the proposed local governments a Twitter-based and rescue safety confirmationexperts need systemto have calleda solution T-@npi. to quickly The proposed gather su systemch tweets enables from the Twitter. victims In to this easily paper, share we their proposed safety informationa Twitter-based and safety rescue confirmation requests including system essential called T-@npi. components. The proposed The registered system informationenables the victims can be to easily share their safety information and rescue requests including essential components. The registered information can be mapped on an online map for quick responses by local governments

Future Internet 2020, 12, 14 14 of 16 mapped on an online map for quick responses by local governments and rescue experts. The system encourages not only self-help, but also mutual and public help, which are important for disaster prevention and mitigation. The registration of safety information was evaluated in an operational test of the proposed system. In future work, we will apply the proposed application to disaster prevention drills in collaboration with local governments. We will also extend the present application into a dual-purpose application that can be used on a daily basis.

Author Contributions: Conceptualization, K.U.; Software, K.U. and M.A.; Validation, K.U., S.N. and M.A.; Investigation, K.U. and M.A.; Resources, K.U.; Data Curation, S.N. and M.A.; Writing-Original Draft Preparation, K.U.; Writing-Review & Editing, O.U.; Visualization, K.U.; Supervision, K.U. and O.U.; Project Administration, O.U.; Funding Acquisition, K.U., and O.U. All authors have read and agreed to the published version of the manuscript. Funding: This study has been supported by the following funds. Grant-in-Aid for Scientific Research (KAKENHI) 17K12989, Japan Society for the Promotion of Science (JSPS) and Tokai University General Research Organization. Conflicts of Interest: The authors declare no conflict of interest.

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