{"id":32868,"date":"2026-06-10T08:56:56","date_gmt":"2026-06-10T08:56:56","guid":{"rendered":"https:\/\/trendifyhubusa.com\/index.php\/2026\/06\/10\/m6-1-earthquake-strikes-northwest-of-cuba\/"},"modified":"2026-06-10T08:56:56","modified_gmt":"2026-06-10T08:56:56","slug":"m6-1-earthquake-strikes-northwest-of-cuba","status":"publish","type":"post","link":"https:\/\/trendifyhubusa.com\/index.php\/2026\/06\/10\/m6-1-earthquake-strikes-northwest-of-cuba\/","title":{"rendered":"M6.1 earthquake strikes northwest of Cuba"},"content":{"rendered":"


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Can you help? We are working to make earthquake science accessible to the public, but this effort is entirely supported by readers like you. If you can, please consider supporting our work by upgrading to a paid subscription. If you use our Substack as part of a group, or for teaching, consider a <\/span>teaching or institutional subscription<\/a>. Every paid subscription makes a real difference \u2014 and unlocks access to the more than three hundred posts in our archive!<\/span><\/em><\/p>\n<\/div>\n

On June 8, 2026, a <\/span>magnitude 6.1 earthquake<\/a> struck offshore of the northwest coast of Cuba. Weak to light shaking was felt in parts of Mexico\u2019s Yucat\u00e1n Peninsula, across all of Florida, and presumably in much of Cuba (although reports from Cuba are sparse). Over 5,000 people <\/span>reported feeling shaking to the USGS<\/a>.<\/span><\/p>\n

People on the coast of Mexico facing the earthquake report that the shaking was clear \u2014 in one case almost knocking over a television or causing faint dizziness. Further away in Florida, the sensation was more mild. One person in Palmona Park, about 540 kilometers from the epicenter, <\/span>reported to the EMSC<\/a>:<\/span><\/p>\n

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I felt a small shake lasting 3-5 seconds. Wife doesn\u2019t believe me as always. Glad to know I was right for once. <\/p>\n<\/blockquote>\n

Another in Gainesville, 820 kilometers from the epicenter, gave a vivid description:<\/p>\n

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I was laying in bed taking a nap this afternoon and felt what felt like gently rolling waves like when you\u2019re sitting in an anchored fishing boat and another boat passes in the distance and eventually the ripple waves reach and gently rock your boat. I checked to see if my AC was maybe vibrating but it wasn\u2019t running. It felt like ripple \u2026 ripple \u2026 ripple \u2026 ripple \u2026 ripple \u2026 stop<\/p>\n<\/blockquote>\n

In regions with regular seismic activity, a mild ripple like that would not usually send people to their devices to log their experience. However, earthquakes are quite rare in Florida. We certainly appreciate the reports and comments!<\/p>\n

This is one of those rare large earthquakes for which there is little to no previous record of nearby seismicity. The USGS catalog contains only three events in the surrounding several hundred kilometer radius, none large. <\/p>\n

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Figure 2<\/strong>: A map of a lonely earthquake offshore of Cuba<\/span><\/figcaption><\/figure>\n<\/div>\n

In fact, when we expand the map dramatically, it appears that this recent M6.1 earthquake is the largest earthquake on record across the entire Gulf of Mexico! The next largest is a M5.9 in 2006. Much larger earthquakes have been recorded around the edges of the map below; perhaps the most surprising to our readers might be the M7 Charleston earthquake of 1886 \u2014 but as far as the Gulf goes, this latest event certainly stands out.<\/p>\n

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Figure 3<\/strong>: The wider view of recorded earthquakes in and around the Gulf of Mexico, per USGS records.<\/span><\/figcaption><\/figure>\n<\/div>\n

We usually present earthquake maps with lots of events and data, which we can use to tell some kind of tectonic story. Here, our usual tools fail us. But that doesn\u2019t mean we have no information \u2014 we just have to look more widely.<\/p>\n

The region offshore of northwest Cuba is well known as a petroleum province, which means that a lot of geological study has been done to understand the potential sources and traps for oil and gas. These kinds of studies rely on regional geological mapping, seismic reflection profiles, and drilling. The goal is to construct a reliable history of sedimentation and tectonic deformation, which can guide the search for petroleum. For those of us outside the oil-and-gas field, these studies are still extremely useful, because they can tell us about the geology that we can\u2019t see at the surface.<\/p>\n

We found a detailed report by Christopher Schenk of the USGS, which contains a lot of useful information, and from which we will draw some figures.<\/p>\n

Below, we stitched together a few geological reconstructions over time, dropped in a black star in the general location of today\u2019s earthquake, and noted the very generic tectonic action that was taking place at that time.<\/p>\n

Here\u2019s the basic story, told as simply as possible. And yes, the names at the tops of the maps \u2014 Oxfordian, Barremian, Maastrichtian \u2014 are real terms used in geology to refer to specific time periods. <\/p>\n

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Figure 4<\/strong>: A summary of millions of years of tectonic action around Cuba, via carefully reconstructed maps; figures are modified from the USGS report, Schenk (2008). Black star = approximate location of M6.1 earthquake projected back in time. <\/span><\/figcaption><\/figure>\n<\/div>\n

Once upon a time, long long ago<\/em> there was a great supercontinent, Pangea. When that supercontinent began to break up (about 200 million years ago), small ocean basins formed in the intervening spaces between the broken-up continental chunks. (Those seas might have hosted sharks and ichthyosaurs, with dinosaurs on the nearby land.)<\/span><\/p>\n

Present-day Cuba sat at the intersection of several of these growing oceans. To the east, the Atlantic was opening. To the north, the Gulf of Mexico was opening. And to the south, the Caribbean Sea was opening. <\/p>\n

Continental breakup like that \u2014 also called <\/span>rifting \u2014 <\/em>causes a lot of normal faulting. This is what happens when the crust stretches and thins. This thinned, faulted crust sank downward, because it was no longer held up by a thick root of continental material, and was covered by the sea. <\/span><\/p>\n

While some breakups are really fast, others drag on for a long time; that was the case here. The Caribbean and Gulf of Mexico never managed to become real ocean basins like the Pacific or Atlantic; they were stuck between the stubborn North and South American continental masses. <\/p>\n

Around the Latest Cretaceous (think T-Rexes and asteroid impacts), the tectonics shifted gears. The oceanic crust was by now old enough to be cold (and therefore dense), and wanted to subduct. As we discussed in our <\/span>recent (perhaps slightly unhinged) post about the Mediterranean<\/a>, subduction in a constrained setting can make for some pretty active and wild geology.<\/span><\/p>\n

Subduction is a funny thing: on the one hand, it generates new surface mass, in the form of volcanoes. These volcanoes form above the subducting plate, the result of the water entrapped in the rocks; when released, that water causes melting and magmatism. But subduction also pulls continents together. When the intervening oceanic crust runs out, the volcanic arc collides with whatever was being dragged along behind. The cycle of supercontinent breakup, ocean basin formation (rifting), subduction, and collision to form a new supercontinent is called the <\/span>Wilson Cycle<\/a>.<\/span><\/em><\/p>\n

We see a micro version of the Wilson Cycle in the Caribbean: starting with rifting, running through subduction and new volcanic arcs, which advanced toward the southern edge of North America (think the Bahamas), and ending in collision, forming a large mountain range that rose above sea level and now defines the curve of Cuba. <\/p>\n

And here\u2019s the key: faults that form at one moment in time stick around, as long as the rocks they are in are still present. That means that the crust beneath the Gulf of Mexico contains normal faults (from rifting) and thrust faults (from collision). And, because the normal faults were still there when the collision occurred, some of those normal faults lived a second life as thrust faults \u2014 slipping in the opposite direction!<\/p>\n

This is called tectonic inversion, and it is a very interesting feature for petroleum geologists, as it can create the folds that trap pooled oils and gas below ground.<\/p>\n

Here\u2019s a cartoon showing how this history has created the present-day geology, again from the USGS report. You have to read it from the bottom to the top, like some kind of ancient scroll:<\/p>\n

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Figure 7<\/strong>: Cartoon cross sections over time of the earthquake area; A is older, E is younger. From Schenk (2008).<\/span><\/figcaption><\/figure>\n<\/div>\n

A \u2192 breakup and rifting; C \u2192 initial collision; D \u2192 thrusting advances, possibly with inversion of older normal faults (not shown). E \u2192 the situation today. This particular image does not show tectonic inversion, but it could have.<\/p>\n

What does this all mean for us?<\/p>\n

The focal mechanism of the earthquake shows that it was a thrust event, on a fault oriented northwest-southeast dipping ~46\u00b0 in one direction or the other.<\/p>\n

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The earthquake occurred just northwest of Cuba \u2014 so right near the previous boundary where a tectonic collision happened, imprinted on previously rifted crust.<\/p>\n

On the following cross section, we have added a queried star where a thrust-type earthquake might plausibly happen today, in the area of potentially inverted normal faults, given the right stresses.<\/p>\n

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Figure 8<\/strong>: A cartoon of the earthquake region in cross section, from Schenk (2008) – we added a star where the M6.1 earthquake might have happened.<\/span><\/figcaption><\/figure>\n<\/div>\n

It is certainly possible to imagine that a thrust-type earthquake might occur on an ancient normal fault. What would drive that earthquake? Well, given that this earthquake occurred in an otherwise seismically quiet area, we can probably class it with other earthquakes that occur in the interiors of plates. The explanation is always a little hand-wavy: the jostling of tectonic plates causes stresses that are transmitted into plate interiors. These stresses seem to concentrate in areas with preexisting weaknesses and cause occasional earthquakes. <\/p>\n

It\u2019s fun to learn new geology, and perhaps useful, but we should also be realistic. We will probably never know which fault slipped (although there is a huge amount of seismic data in this region and perhaps someone with access will chime in usefully?). One earthquake is just not enough \u2014 we can easily come up with a wrong interpretation from just one event. <\/p>\n

For example, the orientation of the fault seems to roughly match the axis of rifting. However, it isn\u2019t really what we would expect if somehow this earthquake still reflected the collision that built Cuba; the shortening direction is perpendicular to the expected direction. <\/p>\n

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Figure 9:<\/strong> another tectonic map of the area around the Gulf of Mexico; we added the focal mechanism. Modified from Figure 1 of Pindell and Kennan (2009).<\/span><\/figcaption><\/figure>\n<\/div>\n

Perhaps there are other profitable ways to think about this earthquake; we are open to all suggestions from our readers!<\/p>\n

This widely felt earthquake seems likely to remain something of a mystery, unless further seismic activity tells us something new. That being said, this is a great example of how an unusual earthquake can stimulate our curiosity. Who knew that a non-dangerous earthquake widely felt in Florida would lead us on a new geological journey?<\/p>\n

Bradley, K., and Hubbard, J., 2026. Deep M6.2 earthquake offshore southern Italy. <\/span>Earthquake Insights, <\/em>https:\/\/earthquakeinsights.substack.com\/p\/deep-m62-earthquake-offshore-southern<\/a><\/p>\n

Pindell, J.L. and Kennan, L., 2009. Tectonic evolution of the Gulf of Mexico, Caribbean and northern South America in the mantle reference frame: an update. Geological Society Special Publications. <\/span>https:\/\/doi.org\/10.1144\/SP328.1<\/a><\/p>\n

Schenk, C.J., 2008. Jurassic-Cretaceous Composite Total Petroleum System and geologic models for oil and gas assessment of the North Cuba Basin, Cuba. <\/span>US Geological Survey North Cuba Basin Assessment Team, Jurassic-Cretaceous Composite Total Petroleum System and geologic assessment of oil and gas resources of the North Cuba Basin, Cuba: US Geological Survey Digital Data Series DDS-69-M<\/em>, p.94. <\/span>https:\/\/pubs.usgs.gov\/dds\/dds-069\/dds-069-m\/REPORTS\/69_M_CH_2.pdf<\/a><\/p>\n<\/div>\n


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