Yesterday an earthquake of magnitude 6.8 Richter struck northern Argentina. The quake occurred at a depth of approximately 610 km, causing no damage to the surface.
Yesterday, 20 January 2023 , at 7:09 pm local time an earthquake of magnitude Richter 6.8 hit northern Argentina, about 24 km from the town of Campo Gallo . Despite its high magnitude, the earthquake caused neither surface damage nor casualties since its hypocenter was located about 610 km deep - at least according to the first analyzes carried out by the USGS .
What are the causes of the earthquake?
Argentina, as well as a large part of South America, is located along the so-called "Pacific ring of fire", i.e. a very long subduction zone along which volcanic and seismic phenomena are frequent. More specifically, the subduction of the Nazca plate under the South American plate occurs in this area . Let's take the image below as a reference.
The various dots represent the most intense earthquakes recorded historically: the bigger the dot, the more violent the earthquake; the more purple it is, the deeper it is. As we can see, the area affected by today's earthquake is characterized by deep earthquakes (the purple dots aligned on the right) and medium-high intensity.
Why do deep earthquakes mainly occur here ?
If we take a closer look at the image, we see the presence of dashed green lines. Their thickness indicates the depth of the subducting plate: in the case of the Campo Gallo area, this value is in the order of hundreds of km , therefore in line with the data recorded today. The depth of the hypocenter causes most of the energy to be dissipated before reaching the surface, creating no particular damage.