Magnitude 7.0 Earthquake Strikes Off Humboldt County, California: Tsunami Warning Lifted After About 70 Minutes
A magnitude 7.0 earthquake struck off the coast of Humboldt County, California, on the morning of December 5. The U.S. Geological Survey (USGS) recorded the quake at 10:44:21 a.m. local time, with its epicenter about 70 kilometers southwest of Ferndale, just west of the Mendocino Triple Junction.
The U.S. National Tsunami Warning Center issued a tsunami warning within five minutes of the quake, based on a preliminary magnitude of 7.3; the warning area ran from Davenport, California, north to the central Oregon coast. The USGS later revised the magnitude to 7.0 and determined the faulting to be strike-slip. The warning center kept the warning in place out of caution over a possible submarine landslide, and canceled it about 70 minutes after the earthquake.
A post-event review by NOAA's Tsunami Science and Technology Advisory Panel reported that a tide gauge at Arena Cove in Mendocino County recorded a small tsunami of about 10 centimeters in amplitude, and that no tsunami damage or on-land flooding was reported.
Starting the next day, the USGS deployed 114 nodal seismometers in the Eel River Valley, near Cape Mendocino and along the California Highway 101 corridor. A USGS data release states that the combined network recorded 295 aftershocks of magnitude 2.5 or greater in the following five weeks, 14 of them above magnitude 4.0. (Source: U.S. Geological Survey)
Source: U.S. Geological Survey
Published by GSM · USA (original Chinese edition)
Photo: 图：美国地质调查局（USGS）本次地震 ShakeMap 烈度图（事件编号 75095651），公共领域。 / Photo: USGS ShakeMap intensity map for this earthquake (event ID 75095651), public domain.
