You will need to use either all 'Variable' properties or all 'Data' properties with geobubble. The properties whose names end in 'Variable' are for specifying a column from the source table. The ones that end in 'Data' should be used when you have vector data. In this case, replacing 'ColorData' with 'ColorVariable' will fix the error you saw, but you will get another error because the function also expects the 'ColorVariable' to be categorical. For this, you could add a new column to the table using the discritize function to bin the magnitudes into categories. It would look something like this:
p.MagnitudeCat = discretize(p.Magnitude,0:2:10,'categorical');
gb = geobubble(p,6,7,'SizeVariable','Magnitude','ColorVariable','MagnitudeCat')
The 'SourceTable' property stores the table you specified as the first input argument (p). You could in theory set the 'SourceTable' to a different table with the same column names thereby updating your chart. For example, if you had data for 2017 and 2018 in separate tables you could do the following:
p2017 = readtable('RealQuakes2017.xlsx');
p2017.MagnitudeCat = discretize(p2017.Magnitude,0:2:10,'categorical');
gb = geobubble(p2017,6,7,'SizeVariable','Magnitude','ColorVariable','MagnitudeCat')
p2018 = readtable('RealQuakes2018.xlsx');
p2018.MagnitudeCat = discretize(p2018.Magnitude,0:2:10,'categorical');
gb.SourceTable = p2018; % Swap out the 2017 data with 2018 data
To instead use the 'Data' properties would look like the following. Note, in this workflow you are supplying vectors of data pulled from the table and not the table itself. There is no need to add a new column to the table with this workflow, instead you can supply the data directly. The 'SourceTable' property will be empty in this case.
gb = geobubble(p.Latitude,p.Longitude, ...
'SizeVariable',p.Magnitude, ...
'ColorVariable',discretize(p.Magnitude,0:2:10,'categorical'))
