Alaska earthquakes

M4.8 earthquake 9 km SSW of Point MacKenzie, Alaska

A magnitude 4.8 earthquake struck 9 km SSW of Point MacKenzie, Alaska on Thu, Dec 27, 2018, 5:21 AM AKST (14:21 UTC), 41 km (25 mi) below the surface.

A larger quake followed: M5.0 8 km SW of Point MacKenzie, Alaska. This one was a foreshock.

Point MacKenzie forecast More in Alaska

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude: 4.8 (Mw, moment), light
Magnitude from: Alaska Earthquake Center
Local time: Thu, Dec 27, 2018, 5:21 AM AKST
UTC: 2018-12-27 14:21:13 UTC
Depth: 41.0 km (25.5 mi), shallow
Epicenter: 61.286° N, 150.068° W
Region: Alaska
Felt reports: 1,190
Strongest shaking: IV, light shaking
PAGER alert: Green
Tsunami flag: Yes: a large quake in an oceanic region
Status: Reviewed by a seismologist

Magnitude estimates

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
4.8	Mw, moment	Alaska Earthquake Center	Preferred · Preliminary
4.8	Mww, W-phase moment	USGS National Earthquake Information Center	Reviewed · ±0.031 · 102 stations
4.8	ML, local (Richter)	NOAA National Tsunami Warning Center	Reviewed · 24 stations
4.8	Mwr, regional moment	USGS National Earthquake Information Center	Moment tensor · Reviewed

Tsunami

The USGS flags a quake this large in an oceanic region. The flag does not mean a tsunami happened; the tsunami warning centers decide that, and their messages are below when they issued any.

Current tsunami warnings: tsunami.gov. Warnings in force in the US also appear on our alerts pages.

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: IV, light shaking
Peak ground acceleration: 428.0% of gravity
Peak ground velocity: 2.1 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

1,190 people reported to the USGS what they felt; the strongest reported shaking was IV, light shaking.

Estimated impact

The USGS PAGER system estimates deaths and economic losses from the shaking and the population and buildings exposed to it.

Alert level: Green: little or no damage or loss of life expected

Deaths: estimated chance of each range
Range	Chance
Under 1	69%
1 to 10	29%
10 to 100	2%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Economic losses: estimated chance of each range
Range, million USD	Chance
Under 1	65%
1 to 10	30%
10 to 100	4%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Oblique normal
Moment magnitude: 4.8 Mww
Nodal plane 1: Strike 309°, dip 26°, rake -139°
Nodal plane 2: Strike 182°, dip 73°, rake -69°

How well it is located

Reviewed by a seismologist.

Stations used: 319

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 1.8 and up: at least 200 in the 60 days after this one and at least 200 in the 30 days before it.

After

The first 60 of at least 200.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak018gl9gvsc (also filed as ak20556108, at00pkefvc, us2000iy38). Read Fri, Oct 2, 2026, 7:43 AM UTC.