Crowd sourcing disaster management: the complex nature of Twitter usage in Padang Indonesia

•Diverse Twitter data collection strategies are compared for usefulness for disaster management.•Normal Indonesian Twitter usage can be used to prepare for tsunami warning and planning.•Official Tsunami tweeters, e.g., BMKG, might be ignored by influential tweeters, i.e. teenagers.•Study demonstrates strengths and limits of Twitter for early warning & planning and coverage gaps.•Normal Twitter usage assessment prior to a disaster is critical for early warning & response plans.