Alaska notoriously experiences a lot of seismic activity, and in the first nine days of 2019 has been shaken by 81 earthquakes of a magnitude 2.5 or higher according to the United States Geological Survey (USGS). The five highest of these have been magnitude 4.5 or higher, with one even reaching magnitude 6.1. This huge quake shook the US state 54km south-southwest of Tanaga Volcano on January 5.
Why is the Alaska Denali Fault more terrifying than the California San Andreas fault?
Alaska is the most seismically active state in the US say experts and has experienced the second largest earthquake to ever hit the United States – a 9.2 magnitude quake in 1964.
It is located along the notorious Ring of Fire, a horseshoe-shaped arc in the Pacific Ocean which joins the Pacific and North American plates.
This area – where two of the Earth’s tectonic plates meet – is marked by zones known as subduction zones.
And one of the fastest moving underwater tectonic faults is one which lies in southeastern Alaska according to the USGS.
USGS geophysicist Randy Baldwin said: “With a slip rate of more than 2 inches per year, this fault may be one of the fastest-moving strike-slip faults in the world.”
This makes it much faster than the San Andreas fault which lies in California.
In the last century, movement between the tectonic plates at the fault line has caused six earthquakes measuring magnitude 7 or greater.
The USGS says: ”One of those earthquakes, a magnitude 7.8 earthquake near Lituya Bay, Alaska, in 1958, triggered a landslide that sent water 1,720 feet up an adjacent mountainside, one of the highest recorded run-ups of a tsunami.”
As the movement is larger than other plates, the tremors that rock Alaska are more frequent.
Just nine days into this year there have been 81 earthquakes to hit Alaska, six of which have rocked the state at magnitudes of 4.5 or higher.
However, despite the more frequent seismic activity of the Denali Fault in Alaska compared to California – it is the latter which receives the most attention when quakes occur.
This is due to “population factor” says Mr Baldwin.
The geophysicist said: ”California probably gets more media attention than Alaska due mainly to the population factor.”
“Anchorage has a population of around 300,000, while there are numerous large population centres in California.”