Two quakes of magnitude 6.7 and 6.8 struck the Mid-Atlantic Ridge nearly seven hours apart

Two strong earthquakes shook the central Mid-Atlantic Ridge on October 13, 2026, the first a magnitude 6.7 at 05:44:46 UTC and the second a magnitude 6.8 at 12:23:07 UTC. The gap between them was 6 hours and 38 minutes, nearly seven hours. The U.S. Geological Survey lists both as moment-magnitude events, both carry a green alert level, and both struck beneath open ocean near the equator, far from any population.

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The pair is notable for how closely matched the two are, not for any damage. The catalogue shows no other event of magnitude 6.5 or larger in the surrounding equatorial box on those days.

Event us6000u1z5, magnitude 6.7, and event us6000u214, magnitude 6.8

The earlier quake is USGS event us6000u1z5, a magnitude 6.7 at 05:44:46 UTC, located at about 0.17 degrees north and 19.86 degrees west. Its depth is listed as 10 kilometers and labelled operator-assigned, a standard placeholder when the agency has not resolved a depth from the data. It carries no tsunami flag.

The later quake is us6000u214, a magnitude 6.8 at 12:23:07 UTC, about 0.41 degrees south and 19.43 degrees west, also at a listed depth of 10 kilometers. Both entries are marked reviewed in the USGS catalogue, the status given once an analyst has checked the automatic solution. The figures here come from the catalogue query for the two event identifiers, which returns origin times to the millisecond.

Working from those coordinates, the two epicenters sit roughly 80 kilometers apart, one just north of the equator and one just south of it. That separation is a calculation from the listed positions rather than a published USGS figure, and locations of mid-ocean events carry uncertainty. It is enough to say that the second quake did not happen on top of the first.

The timing arithmetic is simple but worth laying out, since the gap is one of the two things that make the pair stand out. The magnitude 6.7 began at 05:44:46 UTC and the magnitude 6.8 at 12:23:07 UTC, so 6 hours, 38 minutes and 21 seconds separate the two origin times. Rounded to the nearest hour that is seven, but it is closer to six and a half hours than to seven and a half, and the exact interval is the figure the USGS catalogue supports. In Eastern daylight time the first quake struck at 1:44 a.m. and the second at 8:23 a.m. on the same Tuesday, and every time in this article is given in UTC, the scale the catalogue uses, to keep the two origin times comparable. Both magnitudes are listed as mww, the moment magnitude derived from W-phase waves, a method suited to large events.

The tsunami flag and the green alert

The larger quake carries a tsunami flag in the catalogue, and the smaller does not. A flag of that kind means a tsunami evaluation was triggered for the event, not that a damaging wave formed, and nothing in the catalogue records a tsunami from either quake. The epicenters lie near 19 to 20 degrees west on the equator, in the open Atlantic and well away from any coastline in the records read.

The alert level is a separate automated product. Green is the lowest tier of the USGS impact alert and signals that little or no damage and few casualties are expected. For a pair of quakes on mid-ocean seafloor, with no population nearby, that is the expected outcome, and it is the reason these two never became a disaster story.

The spreading boundary beneath the Atlantic

The Mid-Atlantic Ridge is the boundary where the plates of the Americas pull away from those of Eurasia and Africa. According to the USGS account of plate tectonics, spreading there averages about 2.5 centimeters per year, or 25 kilometers per million years. That sounds slow, but it has opened an ocean over geological time, and the same page notes that transform faults commonly offset active spreading ridges and produce zig-zag plate margins.

USGS lists large events like these in its significant-earthquake feed, the roll of earthquakes big enough to attract attention. The agency has not, in the records read for this article, published a fault-type assignment for either quake, so the question of whether they ruptured on a spreading segment or on an offsetting fault is left open here.

What can be said is that two events of nearly equal size, about 80 kilometers apart, within a single working day, are the kind of pairing seismologists look at when asking whether one rupture changed the stress around its neighbor. The catalogue does not state that the first caused the second, and nothing in the records read establishes it. Follow-up analysis, including any fault-mechanism solutions, would be published on the two event pages linked above as the agency completes it.

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

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