Less attention has been paid to the information receivers in disaster communication, particularly the way disaster information is considered to be trustworthy by the affected community and how it can increase collective participation in disaster communication, both at research and practice levels. Meanwhile, a lack of trust will prevent the transformation of information into usable knowledge for an effective disaster response because people are unlikely to pay attention and act on information provided by someone with whom they have a lack of trust. Thus, this study aims at gaining an in-depth understanding of community-based disaster communication by conducting a qualitative case study of Jalin Merapi (Jaringan Informasi Lingkar Merapi - Merapi Circle Information Networks) in the 2010 Mt. Merapi eruption with 35 in-depth interviews and 2 focus groups in Mt. Merapi surroundings. Data analysis was conducted with constructivist grounded theory in order to construct a theoretical understanding of how disaster communication is regarded as trustworthy and able to encourage collective participation. by the affected community, and the combined usage of traditional media and new media in disaster communication.

This thesis explains that the perception of the affected community of trustworthy and effective official communication is strongly related to the government‘s promptness in sharing complete and accessible official disaster information, and willingness to engage the affected community and their local knowledge. Thus, this thesis argues that the affected community is worth to be engaged in disaster communication for their culturally-embedded communication and tie strength of the social network, which can encourage trust and collective participation. In order to effectively facilitate community participation, disaster communication needs to engage multiple media, both the advanced internet-based and traditional media, based on the local communication behaviours. Moreover, this thesis details important roles of the affected community as reliable sources, couriers, and on-the-ground verifiers of local information about the needs of survivors and the affected areas during a disaster response. Finally, this thesis acknowledges the challenges of disaster communication with a bottom-up communication approach by involving local communities, based on their knowledge and vulnerabilities in responding to a disaster. Also, this thesis has a number of important implications for the future practice of disaster communication, especially in facilitating effective and trustworthy disaster information for the affected community.