Feb. 9 quake near Mt. Hood ‘nothing to be alarmed’ about

The 3.5, which many Odell and Parkdale residents reported feeling at about 9:30 p.m., happened after a series of about 15 1.0 to 1.5 quakes over the previous weeks had happened in the same area — normal seismic activity. Gamberg said a 3.5, while at the threshold where people can feel it, is considered “a small earthquake.”

Mt. Hood, located a few miles away, is one of 161 active volcanoes in the United States.

“It’s nothing to be alarmed. These kind of things happen all the time,” Gamberg said. “Earthquakes by nature tend to be clustered, so an area will light up for awhile and then turn off.”

“This is part of the on-going behavior and in this part of the country it can happen anywhere,” Gamberg said.

“Partly is it is more easily felt because this one was fairly shallow and easier to feel. It’s probably in some indirect way related to the volcano but not in a clear way, There is not a type of magma that it connects to, but a big edifice like a volcano is going to put stresses on the earth, and localizing, but a 3.5 can happen just about anywhere in the U.S. and not be alarming.

Gamberg said the Feb. 9 event “is far enough away and probably some indirect linkage but most of the precursory earthquake activity we see occurs closer to the vocano. It’s generally true that most eruptions have accompanying earthquakes, but the reverse is not true at all.”

The 3.5 was six kilometers deep (3.7 miles) which Gamberg said “was not extraordinarily shallow but in the normal range. She said damage-causing earthquakes historically tend to be deeper.