A 3.4 jolt rattled Calumet, Oklahoma, early on Nov. 7, USGS says

At 5:53 a.m. Central time on Nov. 7, a small earthquake shook the ground about 6 kilometers east of Calumet, a town in Canadian County, Oklahoma. The U.S. Geological Survey reports a local magnitude of 3.38, which rounds to 3.4, and a depth of 5.8 kilometers. It was a shallow event, and strong enough for 23 people to say they felt it.

Help yourself and the planet: The Cool Down makes it easy to help yourself while helping the planet, with smart, simple changes to save more and waste less in your everyday life.

Get The Cool Down →

We may earn a commission if you sign up.

Oklahoma has a long record of quakes at this size, and a reading in the low 3s rarely causes structural harm. The interesting part of the USGS record is how much it can say about a quake of that scale within hours.

USGS readings from the Calumet quake

The agency’s event page lists the origin at 11:53:43 UTC, which converts to 5:53 a.m. on the Central Standard clock now in force. Machine-readable detail pulled from the agency’s event service shows the solution marked as reviewed, meaning an analyst checked the automatic result. The magnitude type is local magnitude, the scale regional networks in Oklahoma commonly use for small events, and the 3.38 value is where the rounded 3.4 comes from.

A depth of 5.8 kilometers is shallow even by earthquake standards. Quakes that originate within the upper crust often generate more noticeable surface shaking per unit of magnitude than deeper ones, since less rock sits between the source and the ground, though a 3.4 remains modest in absolute terms. Felt reports were filed from the surrounding area, and the agency’s community intensity estimate peaked at 4.8, roughly the level where windows rattle and sleepers wake.

Scale matters for reading the number. Each step of one unit in magnitude corresponds to roughly 32 times more energy released, so the 3.38 in Oklahoma carries about a thousandth of the energy of the magnitude 5.5 quakes that struck Japan on the same day. Quakes under magnitude 4 seldom damage well-built structures, though they can topple loose items near the epicenter.

The USGS reviewed status deserves a note too. Automatic solutions for small events are sometimes revised by a few tenths as analysts add stations, and a reviewed label means that process finished. The 3.38 and the 5.8-kilometer depth are therefore the settled values rather than the preliminary ones, and the rounded 3.4 used in news summaries tracks them closely.

Felt reports and community intensity

Twenty-three people had submitted accounts as of the check on Nov. 7. The USGS gathers these through its citizen science felt-report program, which turns each submission into a map of shaking intensity by ZIP code. A count of 23 is small, which is expected for a quake at 5:53 a.m., but the 4.8 peak shows that a few respondents close to the epicenter experienced noticeable shaking.

The program also asks respondents what objects moved, whether they were indoors, and how they reacted, then converts those answers into a numerical intensity for each ZIP code. Because the form is open to anyone, the agency screens for duplicates and obvious errors before plotting. That is why the maximum of 4.8 for this quake is a reliable statement of the strongest shaking reported, though not a measurement of ground motion.

The reports are voluntary and skew toward people who were awake or lightly asleep. They describe how a quake was experienced, not how strong it was; magnitude comes from seismometers and intensity from people. When the two diverge, depth and distance usually explain the gap.

Calumet’s earlier jolt and the induced-seismicity backdrop

This was not the first Calumet-area event in the past week. The agency’s rolling seven-day magnitude 2.5 and above feed also lists a magnitude 2.75 shaker about 6 kilometers east-northeast of Calumet on Nov. 5, at 10:31 UTC and a depth near 6.6 kilometers. The Nov. 7 quake came about two days later in nearly the same spot, which suggests a single active patch of crust rather than two unrelated shocks.

Oklahoma’s seismicity drew national attention in the 2010s, and the USGS maintains a research program on induced earthquakes and has identified Oklahoma and southern Kansas as an area of high induced-earthquake hazard in its hazard estimates. The agency’s event page for Calumet does not assign a cause to this quake, and nothing in the record says whether injection played any role.

Canadian County lies west of Oklahoma City, and Calumet sits along the corridor of small towns west of the metro area. Residents who felt the 5:53 a.m. shake can add their experience to the agency’s survey, which keeps accepting reports after the event and can raise the felt count above the 23 recorded on Nov. 7.

Whether the Calumet sequence continues is the open question. Two shallow events of 2.75 and 3.38 inside about two days at nearly the same distance from Calumet is a pattern the USGS network will keep logging, and any further shock would show up in the same feed within minutes.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

Help yourself and the planet: Get The Cool Down →

We may earn a commission if you sign up.