M 5.5 Moderate Earthquake Recorded South of Nikolski, Alaska
Areazine synthesizes this USGS earthquake report directly from USGS's official public data feed. See our methodology for full source attribution and refresh cadence.
A magnitude 5.5 earthquake struck 97 km south of Nikolski, Alaska, on March 20, 2026. The shallow event occurred at a depth of 10.97 km and triggered a tsunami flag.
What this USGS earthquake report tells you, and what most readers miss
This notice was issued by USGS on April 6, 2026 and geographically references Alaska. Its severity classification of "high" signals how the issuing agency weighs the risk of harm if no action is taken - "critical" and "high" tier alerts typically carry direct consumer actions, while "medium" and "low" tend toward informational guidance or monitoring advisories. The category it belongs to - Earthquakes - determines the monitoring protocol behind it, which shapes what follow-up action (checking for structural damage, watching for aftershocks, reviewing local building codes) is relevant and which agency holds authority over the assessment.
Most readers skim a notice like this, check whether they are personally affected, and move on. The more useful lens is to verify its scope, source, and timestamp, then compare related notices without assuming that one record proves a broader trend.
Areazine pairs this record with the original agency URL so you can check the primary source before acting. Its related labels are earthquake, seismic, usgs, 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.
Original source: USGS Official Notice ↗
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