The unknown type shock had a moment magnitude of 6.5 and a maximum Mercalli intensity of VII (Very strong).

[1] The history of the subduction complex spans for about 150 million years, with significant events happening in this time period.

[4] In local areas, chimneys toppled, windows shattered, and ancient buildings swayed dangerously.

[6] The earthquake caused the Humboldt County courthouse to be deemed uninhabitable, prompting reconstruction of the building.

[6] Soldiers of the United States Armed Forces inspected some harbors of the Humboldt County for damage.