Now that is a BIG earthquake! The European Space Agency (ESA) has reported that a European satellite (GOCE) collecting data about the Earth’s gravity has shown that the violent 9.0 earthquake that hit Japan in March 2011 left a ‘mark’ on Earth’s gravity.
Large earthquakes can not only deform Earth’s crust, but can also modify local gravity which can vary from place to place on our planet’s surface. These tiny changes were measured by sensitive instruments aboard GOCE. The quake in Japan had clearly ruptured the gravity field and left evidence of its effects, those instruments revealed. Now that is an GREAT earthquake that lives up to its name! 😉
Apparently local gravity can be changed because the material that Earth has inside is not homogenous and is not distributed equally and violent earthquakes can change even more the material’s distribution inside Earth.
The GOCE satellite mapped Earth’s gravity with unrivaled precision for over four years, but scientists really expected the data to show changes over time – until the Japanese earthquake proved them wrong.
The changes in local gravity caused by violent earthquakes, although tiny, can be permanent, information that can help to a better understanding of quakes and their effects.