Here are some revealing maps of Mt. Rainier seismicity. Similar to the Mt. Hood activity, Mt. Rainier appears to correlate to solar activity.

The above graph shows the monthly average sunspot count from Jan 1, 1990 to present.

Above is the volcanic activity for Mt Rainier during the same time period. Notice the correlation between the sunspot activity and the volcanic earthquake activity. The relationship of the solar activity to this volcano's activity is yet another demonstration that high energy radiation from the sun causes internal earth heating.