Mobile apps have the potential to aid disaster response by providing an avenue to distribute relevant and time-critical information to the public. Disaster apps already exist in the app markets. However, it is a challenge to engage users in retaining disaster apps on their smartphones. A mixed-methods approach is used in this study to investigate whether usability factors affect users’ intention to continue to use an app (referred to here as continuance intention). First, quantitative methods, applying structural equation modelling with survey data from 271 disaster app users, tested a usability–continuance model. Second, a qualitative usability inquiry, using in-depth interviews with 18 participants, explored the users’ insights of the relationships identified from the quantitative modelling. The results showed five usability factors to have significant influence on continuance intention. The key positive influencers are (1) users’ perceptions as to whether the app delivers its function (app utility); (2) whether it does so dependably (app dependability); and (3) whether it presents information that can be easily understood (user-interface output). Subsequently, too much focus on (4) user-interface graphics and (5) user-interface input can discourage continuance intention. The insights from the qualitative inquiry provide further meaning and context to these relationships. The results have practical implications for designers and developers, guiding what factors to focus on to enhance the continuance intention of disaster apps.

通过提供向公众分发相关且对时间要求严格的信息的途径，移动应用程序具有帮助灾难响应的潜力。应用市场中已经存在灾难应用。但是，让用户参与在其智能手机上保留灾难应用程序是一个挑战。在这项研究中，使用了一种混合方法方法来调查可用性因素是否会影响用户继续使用应用程序的意图（此处称为持续性意图）。首先，定量方法将结构方程模型与来自271个灾难应用程序用户的调查数据一起应用，测试了可用性-持续性模型。其次，通过对18位参与者的深入访谈，进行了定性可用性查询，探索了用户对从定量建模中识别出的关系的见解。结果表明，五个可用性因素对延续意愿有显着影响。关键的积极影响者是（1）用户对应用程序是否提供其功能的看法（应用程序实用程序）; （2）是否可靠（应用程式可信赖性）；（3）是否提供易于理解的信息（用户界面输出）。随后，过多地关注（4）用户界面图形和（5）用户界面输入会阻碍持续性意图。定性探究的见解为这些关系提供了进一步的意义和背景。结果对设计人员和开发人员具有实际意义，指导着重于哪些因素以增强灾难应用程序的持续性。