Hey Seattle, the mountain is out—and she’s a little more lively than usual. Hundreds of small earthquakes at Mount Rainier have been detected this month starting on Tuesday, July 8. It’s not time to freak out yet, however: this is still within the range of normal activity and there is currently no cause for concern.
It is, however, a record-breaking event. This is the largest earthquake swarm ever recorded at Mount Rainier. As of July 23, Pacific Northwest Seismic Network has located 895 earthquakes one to four miles below the volcano. These earthquakes are all very small, however. The largest was a magnitude 2.4 earthquake on July 11.
Since the swarm’s peak activity on July 8, the frequency of the earthquakes has decreased. The cause of this swarm is not known for sure but according to USGS, “Past swarms have been attributed to circulation of fluids interacting with preexisting faults.”
Read on for more details about this interesting phenomenon, and for information about what to do if Mount Rainier ever does erupt.
This earthquake swarm was detected by the U.S. Geological Survey Cascades Volcano Observatory (CVO) and Pacific Northwest Seismic Network (PNSN). They will both continue to monitor earthquake activity at Mount Rainier using a network of webcams, seismometers, GPS stations, and infrasound sensors.
In a statement about the event, the U.S. Geological Survey announced: “Currently, there is no indication that the level of earthquake activity is cause for concern, and the alert level and color code for Mount Rainier remain at GREEN / NORMAL.” Although this is a larger amount of earthquakes than typically seen, this type of earthquake swarm does occur at Mount Rainier about once or twice a year.
Still, seismic activity like this serves as a reminder to have a disaster kit prepared. Here in Seattle, we’re lucky to be surrounded by so much natural beauty—but with that beauty comes the risk of natural disasters such as earthquakes and volcanic eruptions.
If Mount Rainier were to erupt, the threat to Seattle is low. Although Rainier is considered to be one of the most dangerous active volcanoes in the United States due to the threat of harm to nearby populated areas, it is unlikely that mud flow or debris would reach Seattle. However, we do still live with the threat of earthquakes here.
Here are a few of the essentials to include in your emergency kit if you live in Seattle (source):
- Two weeks’ worth of non-perishable food
- A can opener
- Water (one gallon per person per day)
- Pet food and supplies
- First aid kit
- Flash light
- Prescriptions
- Glasses and/or contact lenses if needed
- Flashlight
- Batteries
- Warm clothes and sturdy shoes
- Toilet paper
- Small bills
- Important documents
- Face masks
To get more updates about Mount Rainier, you can visit the volcano-alert notifications page on the USGS website.