Volcanic tremors and earthquakes must be monitored to gain insights into volcanic activity. Localization of their sources is often challenging because of the unclear onset of seismic waves, particularly during an increasing volcanic activity. Existing alternative techniques are based on the information on the spatial amplitude distribution or travel time difference of seismic waves. We propose a new location method that combines both information, obtained from the cross-correlation of seismic data. Evaluation using known volcanic earthquakes at Tokachidake volcano, Japan, reveals some improvements in location accuracy as compared with existing methods using individual information. We further analyze an episode of volcanic tremors and earthquakes accompanying a rapid tilt change event on 14 September 2020. Source locations are mostly distributed at <1 km depth, with evidence of source movement towards the 62-2 crater. Our method is useful in detecting seismic source changes that may represent volcanic fluid migration at shallow depths.