The 7.4 magnitude earthquake that shook Colombia this Monday, August 10 has had a considerable reach. Although its epicenter has been located near San José del Palmar, in the department of Chocó, the movement has been felt in numerous Colombian cities and also outside the country.
The shaking reached Cali, Pereira, Armenia, Manizales, Medellín, and Bogotá, among other cities. There are also reports that the earthquake was perceived in neighboring countries. Reuters confirms that the movement reached Venezuela, while Associated Press reports that it was also felt in Ecuador.
But how can an earthquake with an epicenter in the west of Colombia be felt hundreds of kilometers away?
A magnitude of 7.4
The first element that allows understanding the reach of the earthquake is its high magnitude. Initial estimates were revised during the hours following the movement to place it at 7.4. Reuters and Associated Press report that magnitude in their latest information about the earthquake.
The magnitude reflects the energy released by an earthquake. Furthermore, it is expressed through a logarithmic scale, so a relatively small increase in magnitude represents a much greater increase in the energy released.
The power of the earthquake this Monday allows us to understand, therefore, that the seismic waves may have been able to propagate over a very wide area of the territory.
Depth, another key factor
Depth is another element that must be taken into account to understand why the earthquake was felt at such a distance. At this point, however, the figures released during the first hours have been changing as the data was reviewed.
In the information provided by the director general of the Colombian Geological Service, Julio Fierro Morales, it is mentioned that there are 88 kilometers of depth. Other international sources handle different values: Associated Press, for example, places the depth at 107 kilometers.
Therefore, while the technical review of the earthquake continues, it is more prudent not to set a depth different from that communicated by the head of the SGC as a definitive figure.
In general terms, the depth at which an earthquake originates influences both how it is felt on the surface and the geographical extent over which its seismic waves can be perceived.
Epicenter and hypocenter are not the same
To understand the phenomenon, it is also advisable to differentiate two concepts. The hypocenter is the point inside the Earth where the rupture that causes the earthquake begins. The epicenter, for its part, is the point on the surface located directly above that area.
In the earthquake this Monday, the epicenter has been located near San José del Palmar, in Chocó.
This also explains why talking only about the distance of a city from the epicenter is not enough to determine how an earthquake will be felt.
From Chocó to Bogotá
The wide reach of the movement is reflected in reports from different cities. Reuters points out that the earthquake was felt as far away as Bogotá, located approximately 400 kilometers from the epicenter, although the mayor of the capital, Carlos Fernando Galán, initially reported that no significant damage had occurred.
The situation has been different in closer areas. The governor of Chocó, Nubia Carolina Córdoba, reported the existence of injuries and significant damage to structures in the department. Reuters also reports serious damage and injuries in Pereira.
In Cali, there have also been reports of damage to buildings and structures, while emergency agencies continue to assess the damage.
The earthquake also crossed the borders of Colombia
The extent of the seismic waves was not limited to Colombian territory. Associated Press confirms that the earthquake was felt in Ecuador, where evacuations of buildings and homes also took place. Reuters, for its part, reports that the movement reached Venezuela.
The earthquake thus demonstrates the considerable geographical extent that a movement of this magnitude can reach: from its epicenter in western Colombia, the shaking was felt hundreds of kilometers away and crossed the country's borders.
Colombian authorities continue to assess the consequences of the earthquake and review the technical parameters of the event, so both damage assessments and some seismic data may continue to be updated in the coming hours.