Strong 5.8 magnitude earthquake strikes off east coast of Brazil

January 22, 2013 – BRAZIL – A rather shallow 5.8 magnitude earthquake struck the ocean floor just off the coast of Brazil, south of the popular tourist destination of Natal. The eastern coast of Brazil is relatively free from faults and is not located on the border of any major tectonic plates. So this earthquake is quite unusual. If we look at the seismic hazard map of Brazil (below), it’s clear to see that most of Brazil’s seismic hazards lie in the western part of the country. See local quake map of Brazil.

In 2010, Brazilian seismologist João Carlos Dourado, from Universidade Estadual Paulista, explained in an interview to G1 that Brazil is located at the center of the South American tectonic plate and therefore away from the stresses on the plate edges, which cause earthquakes of the magnitude that plague Chile and countries on the western coast of South America. Today’s earthquake struck at a depth of 15.1 km (9.4 miles) under the Atlantic Ocean floor. The epicenter of the earthquake was 93 km (57 miles) E of Itamaraca, Brazil. ¹

Unusual: Is this quake from a previously unknown fault this close to the shoreline or might other factors be at work here…like the area of growing weakness of the planet’s magnetic field in the South Atlantic Anomaly? Natal is virtually near the epicenter of the SAA. The South Atlantic Anomaly (SAA) is an area where the Earth’s inner Van Allen radiation belt comes closest to the Earth’s surface dipping down to an altitude of 200km (124mi). This leads to an increased flux of energetic particles in this region and exposes orbiting satellites to higher than usual levels of radiation. The effect is caused by the non-concentricity of the Earth and its magnetic dipole, and the SAA is the near-Earth region where the Earth’s magnetic field is weakest.  –The Extinction Protocol