Satellites could detect quakes on Venus.

Strong seismic activity on Venus could cause brief but detectable temperature increases high in that planet's atmosphere, new analyses suggest.

Although Venus is almost the same size as Earth, its atmosphere is about 53 times as dense at the planet's surface as Earth's is at sea level. Therefore, pressure pulses from large ground motions on Venus are probably transmitted more efficiently to high altitudes than such pulses are in Earth's atmosphere, says Raphael Garcia of the Paris Geophysical Institute. He and his colleagues developed a model of how sound would be transmitted through the Venusian atmosphere, which is more than 96 percent carbon dioxide.

The team's analyses suggest that seismic vibrations generated at ground level at frequencies audible to humans would dissipate before they reached altitudes of 80 kilometers. However, pressure pulses resulting from slow ground motions at frequencies below 0.1 hertz, or 1 cycle every 10 seconds, could reach high altitudes. The heating of the atmosphere by those pulses would be strongest at altitudes between 120 and 170 km.

Ground motions from a magnitude 6.0 quake might boost the atmospheric temperature at those heights about 10[degrees]C. That's a large-enough anomaly to be detected easily by a spacecraft orbiting the planet, Garcia and his colleagues note in the Aug. 28 Geophysical Research Letters. The temperature increase high above the quake zone would last for at least 3 minutes--plenty of time for a high-flying satellite to spot the irregularity, says Garcia.--S.P.