M7.3 Earthquake Strikes 58 km WSW of Puerto Madero, Mexico

What Happened?

A magnitude 7.3 earthquake, classified as an Mww (moment magnitude, W-phase) event by the U.S. Geological Survey, struck the Pacific coast of southern Mexico on July 17, 2026, at 14:48 UTC (08:48 local time in Chiapas). The epicenter was located 58 km (36 miles) WSW of Puerto Madero, a small port town in Chiapas state near the Guatemala border, at coordinates 14.604°N, 92.952°W.

USGS recorded the hypocenter at a depth of 18.6 km (about 11.5 miles), placing the rupture on the shallow subduction zone off the Chiapas coast rather than deep within the down-going slab. The agency assigned the event a significance score of 973 and lists its review status as 'reviewed,' its highest confidence level.

A USGS finite-fault model built from seismic waveform data indicates the rupture extended over an area roughly 125 km long and 65 km wide, with a maximum slip of about 2.85 meters and a source duration close to 33 seconds, consistent with a large subduction-zone rupture.

Impact and Felt Reports

The earthquake generated strong to very strong shaking (Modified Mercalli Intensity, MMI, up to VII) close to the epicenter, according to USGS's automated ShakeMap. USGS population-exposure modeling estimates that roughly 694,000 people experienced strong to very strong shaking (MMI VI-VII), about 3.3 million felt moderate shaking (MMI V), and more than 32 million people across Mexico, Guatemala, Belize, Honduras, and El Salvador felt light to moderate tremors.

Towns closest to the epicenter recorded the highest modeled intensities, including Mazatan (population about 7,800, MMI 6.6), Huehuetan (about 36,300, MMI 6.3), Acapetahua (about 26,900, MMI 6.3), and Huixtla (about 54,300, MMI 6.2). Across the border in Guatemala, Ciudad Tecun Uman registered a modeled MMI of 6.0. Tapachula, the largest nearby city with roughly 348,000 residents, saw an estimated MMI of 5.2. Shaking was far lighter in Guatemala City (population 2.9 million), about 217 km away, where modeled intensity dropped to MMI 3.6.

USGS's 'Did You Feel It?' (DYFI) system had logged 283 felt reports by the time of publication, with a maximum Community Determined Intensity (CDI) of 5.4, corresponding to moderate shaking. For more on how these intensity scales differ from earthquake magnitude, see our guide to magnitude vs. intensity.

Casualties, Damage, and Official Response

As of publication, no official reports of fatalities or confirmed structural damage had been released by Mexican or Guatemalan authorities. This article will be updated if Mexico's Servicio Sismologico Nacional, Proteccion Civil in Chiapas, or Guatemala's CONRED publish official damage assessments.

USGS's PAGER system, which estimates likely impact rather than confirming it, placed the earthquake at a Yellow alert level for both fatalities and economic losses. PAGER's automated summary notes that 'some casualties and damage are possible and the impact should be relatively localized,' adding that past Yellow-level alerts 'have required a local or regional level response,' with estimated economic losses under 1% of Mexico's GDP.

PAGER's ground-failure models also flagged a red-level liquefaction hazard, estimating that roughly 110,000 people live in areas modeled as prone to soil liquefaction, a secondary hazard where water-saturated ground temporarily loses strength during shaking. Landslide hazard was modeled as low (green) for this event. These figures are model-based estimates, not confirmed field reports.

Tsunami Status

No tsunami was generated by this earthquake. USGS lists the tsunami flag for this event as inactive, and the Pacific Tsunami Warning Center's public tracker at tsunami.gov confirmed no tsunami warning, watch, advisory, or threat was in effect for Mexico, Guatemala, or elsewhere in the region following the quake.

Large, shallow earthquakes near a coastline can trigger tsunamis when they cause sudden vertical displacement of the seafloor. This event's depth and location did not meet that threshold. For general guidance on responding to coastal earthquakes, see our tsunami safety guide.

Aftershock Sequence

USGS recorded 28 aftershocks of magnitude 4.0 or greater within about 16 hours of the mainshock, an active sequence typical of a large subduction-zone earthquake. The largest aftershock, a magnitude 6.0 event, struck just 32 minutes after the mainshock, roughly 90 km southwest of Puerto Madero. Several additional aftershocks in the magnitude 5.0 to 5.3 range followed through the night and into July 18.

Aftershock sequences like this one typically decay over days to months, though the largest aftershocks can themselves cause additional shaking and, rarely, further damage to already weakened structures. Residents in Chiapas and along the Guatemala border should expect continued aftershocks in the coming days.

Tectonic Setting: Why Chiapas Shakes

This earthquake occurred along the Middle America Trench, where the Cocos Plate subducts beneath the Caribbean Plate boundary off the coast of Chiapas. The moment tensor solution published by USGS shows a shallow-dipping nodal plane (strike 286°, dip 27°, rake 75°), consistent with reverse, or thrust, faulting on the subduction interface itself, rather than a deeper break within the down-going Cocos Plate.

Chiapas and the broader Mexico-Guatemala border region sit above one of the most active subduction zones on Earth. The same stretch of coastline produced the magnitude 8.2 2017 Tehuantepec earthquake, the strongest to hit Mexico in over a century, which killed 98 people and generated a localized tsunami. That earthquake ruptured much deeper, at 47.4 km, within the subducting Cocos Plate itself (an intraslab event), a different mechanism from the shallower interface rupture recorded on July 17, 2026.

USGS's historical comparison tool notes that the closest comparably sized event on record, a magnitude 6.2 earthquake in Guatemala on September 18, 1991, about 218 km from this epicenter, killed 25 people. For an overview of seismic activity across the country, visit our Mexico earthquake tracker.

Earthquake Safety Guidelines

If you are in Chiapas, Guatemala, or elsewhere near the epicenter, expect aftershocks in the hours and days ahead. During any earthquake, the recommended response is to 'Drop, Cover, and Hold On': drop to the ground, take cover under sturdy furniture, and hold on until the shaking stops.

If you are near the coast, move away from the shoreline after any strong or prolonged earthquake, even without an official tsunami warning, and follow guidance from local Proteccion Civil or CONRED officials. For a full room-by-room breakdown of what to do during a quake, see our earthquake safety guide.