IDAHO FALLS, Idaho (KIFI) — Early Tuesday morning, there was seismic activity detected 9 – 10 miles northwest of Stanley. This was the latest in a series of over 20 earthquakes with magnitudes greater than 2.0 since Saturday.
The first of the quakes was shortly after 1:30 a.m. with a magnitude of 4.0. This is the largest quake so far in this cluster.
After that, two more quakes measuring magnitudes of 3.5 and 3.9 occurred just before 6 a.m. A magnitude 3.9 tremor happened just after 7 a.m., and a smaller magnitude 2.5 quake hit just before 8 a.m.
Shortly after 4:35 p.m. on Tuesday, there was another earthquake with a magnitude of 2.7.
It’s a common misconception that after a quake that the tension in the earth has been completely relieved from the area. That’s not entirely true.
Earthquakes occur because of shifting tectonics or forces deep within the earth causing pressure to build up.
The underlying cause of earthquakes, tectonic shift, can build pressure on the same fault lines over and over, causing several earthquakes in the same spot.
It’s also possible that these quakes in Stanley were not part of a ‘series’ , but instead part of an earthquake ‘swarm’.
A series has an identifiable main quake that the procession occurs before or after. A swarm is a bunch of earthquakes with no main quake.
You can’t tell whether it’s a series of foreshock quakes followed by a large quake, or a swarm without a large quake until after either the quakes stop, or a there’s a quake large enough to be identified as the main quake. If it is a swarm, without that clear climactic event, it’s tough to tell when it will die down.
Several counties, including Lemhi and Custer, have sent out Facebook posts providing instructions to prepare for an earthquake.
If you feel an earthquake, remember to DROP, COVER, AND HOLD ON.
We’ll continue to keep an eye on the sky as well as the ground below in an effort to keep you informed and safe.
