Hi All. Thought I would see if I could find any history for past quakes in the area of the latest M>4.5 quake near Mt. Hood. What I found was interesting, but not very revealing as to what the future may be for this area.

Year MoDy Hr:Mn Depth Mag Distance Azimuth Event Location
(UT) (km) (km) (Deg)
1877 1012 17:00 0.0 6.3 66.3 286.4 10.2 km ESE of Portland, OR
1941 1229 18:37 0.0 5.0 76.4 287.3 0.0 km S of Portland, OR
1953 1216 04:32 0.0 5.0 81.5 283.4 7.4 km WSW of Portland, OR
1961 0916 03:24 7.2 4.8 82.7 335.6 21.4 km SSE of Mt St Helens, WA
1961 0916 11:46 7.2 4.0 83.1 335.5 21.0 km SSE of Mt St Helens, WA
1961 0917 15:55 7.2 5.1 83.7 336.2 20.3 km SSE of Mt St Helens, WA
1962 1106 03:36 18.0 5.5 77.5 293.4 8.3 km NNE of Portland, OR
1976 0413 00:47 15.0 4.6 71.1 113.6 20.6 km ESE of Maupin, OR
1976 0417 02:11 15.0 4.0 68.8 106.3 18.4 km E of Maupin, OR
1993 0325 13:34 20.6 5.6 79.7 245.6 23.0 km ESE of Woodburn, OR

As you can see there were 3 quakes associated with Mt. St Helens in 1961. However the eruption of Mt. St Helens didn’t occur until almost 20 years later so this quake doesn’t necessarily mean that Mt. Hood could erupt anytime in the near future. However that can’t be ruled out either.

The moment tensor solution indicates that this was a strike slip quake with normal faulting component. This doesn’t tell us very much either. It just means that the fault could be a right lateral strike slip, or a normal fault. For a reverse fault the material on the upper side of the fault moves up; for a normal fault the material on the upper side of the fault moves down. The moment tensor solution alone can’t tell you this.

What all of this means is that we have another series of quakes to add to the catalog. The earth is trying to tell us something, but at present time we don’t understand what it’s trying to tell us. Take Care…Don in creepy town

• Mt. Hood