It's not just 'suspected'
Pumping water into the ground does cause tremors, a deep disposal well in the Rockies (it was dumping nerve gas effluent, nothing to worry about) could turn earthquakes on and off depending on how much crap it was pushing down the pipe.
They're also reasonably common in Iceland around the sites of their geothermal plants where cool water is being returned to the ground after it has given up its heat.
Actually hot basalt plus CO2 is one of the possible ways of getting rid of greenhouse gases. At suitably high temperatures the two react together to form a mineral called palagonite which is perfectly stable.