Two hours, 29 minutes and 33 seconds after Panama’s magnitude 7.7 earthquake began at 17:56:06 UTC on Friday, Oct. 9, 2026, a magnitude 6.6 struck at 20:25:39 UTC, about 14 km west of Río Grande. That is 3:25 p.m. in Panama, roughly three hours of daylight left for crews already working the ruins of the first shock.
The U.S. Geological Survey carries the second event as its own entry, us6000u19w, with a yellow PAGER alert and a tsunami flag set to 1.
The 2 hour 29 minute gap in the USGS catalogue
The USGS record for the 6.6 gives a moment magnitude (Mww) of 6.6 at a depth of 10 km, a community-reported intensity of 7.1 and a ShakeMap peak of about 8.1, status reviewed. The weekly USGS feed shows the 7.7 at 17:56 UTC and the 6.6 at 20:25 UTC, which is where the less-than-three-hours span comes from.
The shaking figure for the second quake sits below the first quake’s 9.1, and the alert color follows: yellow for the 6.6, against red for the 7.7. In energy terms a magnitude 6.6 releases roughly one-forty-fifth of the energy of a 7.7, since each whole magnitude step is about 32 times and 1.1 units compounds to a factor near 45. The 6.6 was big enough to shake the same provinces again, and small enough that the 7.7 remains the event that set the damage.
The two epicenters are not the same place. The USGS detail record places the mainshock at 7.60° N, 80.76° W, near Pitaloza Arriba in Herrera province, while the tsunami.gov statement for the 6.6 gives 7.8° N, 81.4° W, a longitude about 0.6 degrees farther west. Reports from Panama did not split the damage between the two shocks: CBS quoted Omar Smith of the National Civil Protection Service on several injuries, including one person hit by debris in Penonomé, without saying which quake caused them.
The tsunami flag and the information statement
The USGS record carries a tsunami flag of 1 on the 6.6, unlike the 7.7 entry, which shows 0 in the catalogue listing. The tsunami.gov page read on Oct. 10 shows a Tsunami Information Statement tied to an origin time of 20:25:40 UTC at 7.8° N, 81.4° W, addressed to Alaska, British Columbia, Washington, Oregon and California, and states that no tsunami warning, advisory, watch or threat is in effect for those coasts.
The statement is an information product, not a warning. The warnings for Panama, Colombia, Ecuador, Nicaragua and Guatemala belonged to the first quake, and CBS News reported that the Pacific Tsunami Warning Center had warned of possible waves on Panama’s coast and later said the threat had passed before the second shock arrived.
Eleven other magnitude 5-plus shocks and the Tonosí pair
The USGS catalogue for the box around southern Panama lists 13 events of magnitude 5.0 or higher between the mainshock and 02:26 UTC on Oct. 10: the 7.7, the 6.6 and 11 others. Seven of the 11 fell before the 6.6, among them a 5.5 at 18:22 UTC and a 5.8 at 18:37 UTC, and four came after it, the largest a 5.4 at 23:12 UTC southeast of Los Asientos. The last in the list, a 5.1 at 02:26 UTC, was near Tonosí.
Panama’s own seismologists count differently. The University of Panama’s Geosciences Institute put its two strongest aftershocks near Tonosí at 6.1 and 6.0, according to Diario Libre, and the university’s seismologists recorded more than 45 aftershocks in all, many too weak to be felt, the AP reported. The USGS reviewed Mww of 6.6 is the figure used here for the second large quake.
The Panama Fracture Zone setting
Southern Panama sits where several plates and microplates meet. K.D. Morell, D.M. Fisher and T.W. Gardner’s 2008 study in Earth and Planetary Science Letters, Inner forearc response to subduction of the Panama Fracture Zone, describes the right-lateral Panama Fracture Zone, a Panama microplate separated from the Caribbean plate by diffuse deformation, and a triple junction migrating southeast at 55 mm per year.
The USGS listing for the mainshock includes moment-tensor, finite-fault and aftershock-forecast products, the pieces that will say which fault ruptured and how the 6.6 fits the pattern. Neither USGS nor the University of Panama had attributed the 6.6 to a specific fault in the material available on Oct. 10. Panama’s Civil Protection service has said damage was concentrated in Veraguas, Herrera and Los Santos provinces, the same three the 7.7 hit hardest.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
More from Morning Overview
- Lake Powell sank to a record 3,517 feet, nearing the level that stops Glen Canyon Dam’s turbines
- Seven of Earth’s nine planetary boundaries are breached, and all seven are worsening
- The NSA says three phone features should be off whenever you aren’t using them
- Hurricane Hunter radar shows four warning signs that a tropical cyclone is about to strengthen, a University of Miami study found
