The first quake at 8.55am with a magnitude of 3.3 had its epicentre 3.3 kilometres underground at latitude 19.70 and longitude 99.72.
People felt the tremor but no injuries or damage have been reported.
A 2.0-magnitude tremor followed at 10.14 in Mae Lao district, at latitude 19.74 and longitude 99.69.
The third at 10.37 had a magnitude of 1.9 at latitude 19.70 and longitude 99.72 in Phan district.