HAARP can by heating a regional area of the ionosphere, cause it to "bubble" and as a result, deflect the jet stream. Changes to that can alter the weather over wide swaths of the earth below and induce radical temperature change, noticeable if it is unseasonable, It can also trigger droughts or flooding. As for earthquakes, that would require energies beyond HAARPs capability. Fracking causes more earthquakes than HAARP. If HAARP can be tuned with an X-flare from the sun, then it is more likely, but the strike zone would be unpredictable.