The earthquake that hit Japan in 2011 set many tragic records. It was the most severe measured earthquake in the country and the fourth-most severe earthquake in the world since 1900. Then-Prime Minister Naoto Kan called it “the most difficult crisis for Japan” since World War II. But one small positive record it set was that it was one of the first quakes to be detected from space, via gravity-detecting instruments orbiting the Earth in satellites.
The European Space Agency’s GOCE and NASA’s GRACE satellites both reported sensing sound waves from the Japanese quake. (GOCE is short for Gravity Field and Steady-State Ocean Circulation Explorer and GRACE stands for Gravity Recovery and Climate Experiment.) The waves were infrasound, which is at a frequency much too low to be heard. Infrasound waves from large earthquakes, however, can alter the air pressure or electron density around satellites in orbit around Earth, which the satellites are then able to detect.
Now, astronomers hope to use infrasound measurements to detect earthquakes on Venus. Quakes on Venus likely must be measured by satellite because the planet’s surface is so hot and under such high pressure, seismology equipment wouldn’t be able to survive there. Measuring quakes on Venus would help scientists learn more about the planet’s interior, which happens to be very strange: It lacks some of the essential features of Earth’s interior, including place tectonics and a dynamo mechanism in its core. A team of scientists gave a talk about measuring Venusian quakes at the meeting of the Seismological Society of America last week, but they’ve been proposing Venusquake experiments for several years now.
Measuring infrasound waves from Venusian earthquakes may even be easier than measuring them from Earthly quakes, as astronomers wrote in 2010. The researchers think Venus’ atmosphere will react more strongly to quakes than Earth’s does. The earthquakes may end up offering potent messages about the planets’ interiors, if only we read them right.
