Major US city under volcano advisory rattled by earthquakes

A major Alaskan city was rattled Thursday by two earthquakes that struck just hours apart.

Anchorage, home to around 300,000 people, experienced a magnitude 2.9 quake at 10:13am local time (2:13pm ET) near Elmendorf Air Force Base.

The first tremor, a magnitude 3.2, was detected about 48 miles north at 5:23am (11:32am ET), but residents in Anchorage also reported feeling the shaking, according to the US Geological Survey (USGS).

An assessment from Michigan Tech University showed that people typically do not feel quakes with a magnitude of 2.5 or less.

Those from 2.5 to 5.4 are often felt but only cause minor damage. 

No injuries or damages have been reported on Thursday.

Anchorage sits about 78 miles from Mount Spurr, which continues to show signs of unrest with elevated seismic activity.

Mount Spurr was under an eruption ‘Watch’ earlier this year, but it has since been lowered to ‘Advisory,’ meaning ‘volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.’

Anchorage, home to around 300,000 people, experienced a magnitude 2.9 quake at 10:13am local time (2:13pm ET) near Elmendorf Air Force Base

Elmendorf Air Force Base, like all of Alaska, is prone to earthquakes due to its location along a major tectonic plate boundary.

Specifically, it sits on top of the Aleutian subduction zone, where the Pacific Plate slides beneath the North American Plate, generating significant seismic activity.

This plate movement creates stress that is periodically released in the form of earthquakes, some of which can be quite large.

Elmendorf is the largest military installation in Alaska, as its 13,130 square acres are occupied by more than 800 buildings, two runways and more than 150 miles of roads. 

While the magnitude 2.9 quake is considered minor, dozens of locals reported feeling it to the USGS, while more than 100 reports came in for the stronger tremor. 

Mount Spurr has experienced dozens of small earthquakes in the last week, reaching up to a magnitude 2.

The Alaska Volcano Observatory issued the latest update on Wednesday, saying: ‘Low-level unrest continues at Mount Spurr with occasional, small earthquakes occurring beneath the volcano. 

‘No activity was observed in mostly clear webcam images and satellite views from the past day.’

Anchorage sits about 78 miles from Mount Spurr, which continues to show signs of unrest with elevated seismic activity

However, the volcano was under a ‘Watch’ in March when it began releasing elevated levels of gas from its summit and a side vent that last erupted in 1992.