I have replicated this for the Cairns G20 finance event with the trend for a search on "Cairns". This is the result for the last 90 days. The output here is daily and relative to the peak for the period which was the first spike in September at the start of the G20 weekend. This was just ahead of the second spike there in October which was when the nurse was admitted to Cairns Hospital with the suspected ebola false alarm.
However when we take a longer term perspective over the past year with a weekly trend the G20 (A) is not so prominent. The relative peak here back in April was Cyclone Ita. The other flagged news events with a label are mostly irrelevant or sport related.
Without any expertise on the nuances of Google Trends another perspective is to add a second search term "G20" shown in red. The relative peak here is the Brisbane leaders summit with the minor bump at label 'C" being the Cairns event.
In recent years it has been Cyclone Yasi in 2011 which has dominated the trend relativities which is similar to the Brisbane result where it was the floods at that time also. So to take a longer term perspective this is the available trend on a monthly basis from 2004.
The impact of G20 here would appear to have had minimal impact on the profile of Cairns based on Google Trends. The G20 month is only modestly above the Zumba world record attempt in February 2012.
Previous post back in 2011 on the trend for search terms 'Cairns Australia' and 'Great Barrier Reef': Google Trends & Insights