Comparing felt reports and tweets about earthquakes

This paper describes ongoing work to determine earthquake intensity from information provided by people who experience them, the `felt reports', and from tweets describing the same events. We have studied 10 significant earthquakes in Australia over a six month period. We found a strong correlation between these two sources of information. The felt reports, which are produced by people completing a web form, arrive within a similar time frame as the tweets, although there are many more tweets available. Since the web form prompts for specific impact information, they are easier to process to characterise earthquake intensity, however it is expected that the tweets will be useful to help with this determination. Our aim is to develop a system to process these two data sources to automatically derive a measure of earthquake intensity. This information requires further analysis by seismologists but is a useful indicator of the impact experienced by people.