M 5.5 Moderate Earthquake Recorded South of Nikolski, Alaska

What Happened

A moderate earthquake with a magnitude of 5.5 (mww) occurred south of Nikolski, Alaska. The seismic event was recorded at 08:45:06 UTC on March 20, 2026.

Location Details

The epicenter was located at coordinates 52.0667°N, 168.9394°W, approximately 97 km south of Nikolski. The earthquake occurred at a shallow depth of 10.971 km. Shallow earthquakes, defined as those occurring at depths of less than 20 km, are typically felt more intensely at the surface than deeper seismic events.

Impact Assessment

The USGS has received at least one felt report following the tremor, which registered a Community Decimal Intensity (CDI) of 2. The event reached a maximum estimated intensity of 3.828 on the Modified Mercalli Intensity scale. A tsunami flag (1) is associated with this event, indicating that tsunami potential was monitored or an advisory status was relevant. No specific alert level color was assigned in the source data.

What You Should Know

Moderate earthquakes (M 5.0-5.9) are capable of causing damage to poorly constructed buildings but usually result in light damage to well-built structures. Residents in the Aleutian Islands should remain alert for the possibility of aftershocks. In the event of seismic activity, safety officials recommend that individuals “Drop, Cover, and Hold On.”

Source

Data provided by the USGS.