00:00On August 10, 2026, at 7:34 a.m., 107 kilometers below San José del
00:05Palmar, in Chocó,
00:06A strong earthquake was recorded.
00:08But 150 kilometers to the south, in Cali, the windows rattled, the buildings shook
00:12and thousands of people took to the streets.
00:14How can a deep earthquake travel great distances?
00:18Let's look at the map first.
00:19This representation, based on the Shake Map of the U.S. Geological Survey,
00:23It shows how the earthquake traveled across the western part of the country.
00:26In Pereira, Dos Quebradas, Cartago, Quibdó, Buenaventura and Armenia,
00:31It arrived with a destructive or severe intensity, that is, a level 8,
00:35according to the Mercalli seismic scale, which does not measure magnitude,
00:38but how the movement felt and what effects it might produce in a particular place.
00:43The scale ranges from grade 1, very weak, to 12, cataclysm or extreme.
00:48Rather, here too there would be, and it's worth clarifying that, for example, magnitude,
00:53It refers to the amount of energy that was released by the earthquake.
00:59Next, we have the intensity values,
01:01And that means that specifically on the surface,
01:06Accelerations can be larger or smaller.
01:10And that doesn't really depend on how close you are to the event,
01:15but rather the soil conditions.
01:17In Cali, Manizales, Tuluá and Zarzal, the intensity was level 7, very strong.
01:23In other words, the same earthquake can have different levels of intensity.
01:27depending on where it is measured, such as on August 10th,
01:30that shook the ground beneath the feet of more than 30 million Colombians,
01:34according to the report from the U.S. Geological Survey.
01:36Colombia is located in a geologically complex area,
01:39where different tectonic plates and active faults converge,
01:42according to the Colombian Geological Survey.
01:44We are in an area where tectonic plates converge,
01:48the South American Plate with the Nazca Plate,
01:51that controls all this significance of western Colombia,
01:55And in the case of the north, that convergence with the Caribbean Plate.
01:58Tectonic plates are blocks of the Earth's lithosphere in continuous motion.
02:03In the Colombian Pacific, the Nazca Plate, which is oceanic,
02:06It gradually sinks beneath the continent.
02:08This process is called subduction, and it takes place over millions of years.
02:12And that movement is capable of generating mountains, mountain ranges, and earthquakes.
02:17Here comes the important part.
02:18The earthquake of August 10 did not occur due to the contact between the two plates.
02:22It occurred within the Nazca Plate, at a depth of more than 100 kilometers.
02:26while the plate continued to sink.
02:28The plate didn't break on the outside, it broke on the inside.
02:31It is an earthquake that occurs within the subducting plate,
02:36But when it reaches 100 kilometers.
02:39This means that it is not an earthquake that occurs at the plate interface.
02:43but inside the Nazca Plate.
02:45Why do they occur at those depths?
02:47Precisely between 80 and 100 kilometers,
02:49The oceanic plate is under a lot of pressure,
02:54and that's precisely where it releases energy,
02:56energy, but globally we can say between 80 and 200 kilometers,
03:02Subducting plates generate brittle fractures,
03:07which are basically earthquakes.
03:09But there is another phenomenon that is almost never considered,
03:12It's called liquefaction.
03:13The soil is composed of different particles,
03:15mainly minerals, rock fragments, in short.
03:19And what happens is that when it becomes saturated with water,
03:21He's going to change his behavior.
03:23Something like what happens when we enter the beach.
03:26We are off the beach,
03:28And the bleachers keep us close to the ground, right?
03:31And very stable.
03:32But as we go in,
03:34The water rises through our body.
03:36If we proceed calmly, we can remain stationary.
03:39But we're becoming lighter and lighter.
03:41And if a wave suddenly arrives, well, it's going to throw us off balance.
03:44That's more or less what happens with these soils,
03:46that become saturated with water between the particles,
03:49And when an earthquake strikes,
03:50The whole will behave more like a liquid.
03:54And it will make some things float, while others sink.
03:58And that's where we see significant impacts on the infrastructure.
04:01This time it was observed in Chocó,
04:03one of the rainiest regions on the planet.
04:05These images were collected from social media.
04:08They could be an example of the phenomenon.
04:09Although it is likely to happen in much of the country,
04:12The hypothesis must be tested with field studies.
04:15What on any other day is just tropical rain,
04:17During an earthquake, it becomes a damage multiplier.
04:20And all this is happening in a country where earthquakes are not an exception.
04:24The Colombian Geological Survey records an average
04:27of 2,500 earthquakes per month in the country.
04:30This is an earthquake every 17 and a half minutes.
04:33Most people don't feel it.
04:34But they are happening.
04:36According to the National Disaster Risk Management Plan,
04:38approximately 86% of the Colombian population
04:41lives in areas of intermediate or high seismic risk.
04:44It's not something extraordinary.
04:46It is part of the country's geological reality.
04:48And there is one place that concentrates a good part of that activity,
04:51the seismic nest of Bucaramanga,
04:53located under the Table of the Saints.
04:55It is one of the points with the highest seismic density
04:58of intermediate depth of the planet.
05:00So, in Colombia, the earthquake on August 10th was not due to bad luck.
05:03It shook because that's how Colombia is.
05:04And now, let's return to the question that opened this video.
05:07Why an earthquake with its epicenter in San José del Palmar
05:10can be felt so strongly in Cali,
05:12More than 150 kilometers?
05:14The answer lies once again in the depths.
05:17These waves have the ability to propagate
05:23over perhaps a longer distance in a more homogeneous environment.
05:29When an earthquake occurs near the surface,
05:31Its waves pass through layers of rock that may be more fractured,
05:35soft and full of irregularities.
05:37They lose energy during that journey.
05:39Therefore, shallow earthquakes can be devastating near the epicenter.
05:43but felt much less as the distance increases.
05:46But this was a deep earthquake.
05:48Its waves had to pass through much more compact and homogeneous layers of rock.
05:53before reaching the surface.
05:55Under those conditions they lose less energy
05:57and can spread over greater distances.
05:59Therefore, instead of concentrating its effects near a single point,
06:03The movement could be felt over a much wider area.
06:07Here's an example that helps to understand this.
06:09In 1999, the earthquake in the coffee-growing region was much more superficial.
06:13and had a smaller magnitude,
06:15but it concentrated the energy on a single point.
06:18The result was one of the greatest tragedies ever caused
06:20due to a natural phenomenon in recent Colombian history.
06:23More than a thousand people died.
06:25There is a very interesting example which is when you put, for example,
06:30a lamp very close to something.
06:34Therefore, the halo of light doesn't reach very far.
06:37but the intensity of the light is very high.
06:42When one starts to lower the lamp,
06:44The halo of light can reach more places on the surface,
06:48but the intensity is lower.
06:50This earthquake was different.
06:52Much more energy was released,
06:54but this was distributed over a wider area.
06:57It reached places like Quibdó, Pereira, Manizales, Cali and Bogotá.
07:02It does not mean that one was simply worse than the other.
07:04These are earthquakes with different characteristics
07:07and depth completely changes the rules of the game.
07:10I believe that the most valuable thing that an experience like this leaves us with is
07:13which has a human cost and is very painful
07:17from a social point of view, with its consequences,
07:21It's about understanding a geological phenomenon
07:23And in understanding how we can prepare ourselves, right?
07:27to deal with it.
07:29The importance of earthquake resistance standards,
07:32the importance of understanding the phenomenon,
07:34agree with him and develop skills for this coexistence.
07:38This is the overall picture of how we understand
07:40Earthquakes in Colombia from a geological perspective.
07:43At El Espectador we have other content that you can consult,
07:46the most common myths about these phenomena,
07:48The accounts from our reporters in the affected regions
07:50or the importance of speeding up rescue efforts.
07:53You can find all this content at www.elespectador.com
07:57and on all our social media channels.
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