Earth Science Blog- Earthquakes

Before the ’04 Tsunami, an Earthquake So Violent It Even Shook Gravity

This article discusses the tsunami that struck Indonesia in December of 2004. It is stated that the giant earthquake that set it off actually disrupted the earth enough to change gravity and to deflect satellites passing hundreds of miles above. Two identical satellites travel one behind the other in a polar orbit separated by about 130 miles. By recording changes in the distance between them when their orbits are deflected the satellites provide data to calculated variations in the earths gravitational field.
In a report that in the aftermath of the magnitude 9.1 earthquake, the largest in four decades, on of the satellites Grace recorded a sudden drop in gravity near the quakes epicenter of Sumatra. The rupture caused the seafloor to raise thousands of square miles reducing the density of rocks in the crust and changing their gravitational pull.
This relates to class because we have been talking about earthquakes and why they occur and what affects they have on us. This earthquake by Sumatra happened under water. With what I have learned the plates that caused the earthquake probably shifted quite a lot because the magnitude of the quake was so high. Most earthquakes are under, I would say a 4-5 on the Richter scale. This earthquake was very big and it cause a lot of damage. We learned in class that when an earthquakes focus is under water they cause tsunamis. The shifting of the plates cause the water to shift back and forth creating waves. What we are concerned about is how earthquakes affect us. This particular earthquake was devastating because it killed tons of people and ruined buildings, habitats, and is going to cost so much money to repair everything.