Did You Feel Monday’s Magnitude 4.9 Earthquake In Idaho? What We Know So Far

(CTN News) – Residents of Boise and around the Treasure Valley felt the effects of a magnitude 4.9 earthquake Monday morning.

This quake, which the U.S. Geological Survey reported occurring at 10:25 a.m., was the largest in Idaho since March 2020, when a magnitude 6.5 earthquake occurred. Approximately 50 miles south of McCall, Monday’s quake originated near Smiths Ferry.

A second earthquake with a magnitude of 2.7 was recorded about a mile away at 10:46 a.m.

At 11:20 a.m., the Valley County Sheriff’s Office reported the quakes had not caused any injuries.

According to Idaho Geological Survey director Claudio Berti, the first earthquake surprised geologists. Last week’s magnitude 1.9 temblor near McCall was the only quake recorded by the USGS in recent weeks.

A strong earthquake cannot be detected by signs, Berti told the Statesman. “On occasion, a strong earthquake may actually be an announcement of a larger earthquake; we call them foreshocks rather than aftershocks.

“We don’t yet know if this is a foreshock of a larger event or just a small earthquake,” he said.

Berti said several aftershocks were possible based on previous earthquakes in the Smiths Ferry region, such as the 2.7 magnitude tremor that occurred about 20 minutes after the original. Aftershocks following a large earthquake are common, and Idaho residents shouldn’t be alarmed. Smaller aftershocks might not be felt at all.

To help researchers better understand the earthquake, Idaho residents were asked to report their experiences online at earthquake.usgs.gov.

What is the magnitude of an earthquake of 4.9?

Known as the Moment Magnitude Scale, earthquakes are measured from 0 to 10.

Seismology equipment can detect earthquakes that measure 2.5 or less but are not felt on the surface. 8.0 quakes or stronger can destroy entire communities.

The 4.9 magnitude quake that struck Smiths Ferry on Monday is on the cusp of being a light or moderate earthquake. However, damage can be avoided.

The tremor Monday doesn’t compare to the strongest Gem State quake ever recorded. In March 2020, a 6.5 magnitude quake near Stanley follows the 6.9 magnitude quake near Challis in 1983.

What caused this earthquake?

Smiths Ferry is a known seismic area. This is why the Idaho Geological Survey maintains a seismic station in the region.

Berti says the valley between McCall and Smiths Ferry has formed younger fault lines, which make the area especially active. A fault line may have caused Monday’s earthquake.

“Some of those faults (younger ones) are reactivating old fractures,” Berti said.

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