Seismic imaging of magma chamber beneath an active volcano

While the location and shape of magma chambers beneath active volcanoes play a key role in understanding magma transport and forecasting volcanic activity, the nature of magma chambers, particularly their shape, is not fully understood. Here we found a low velocity body too small to be detected from conventional techniques by the aid of a modern technique called seismic interferometry. Combining our result with independent observations suggests that the low velocity body is likely to represent a magma chamber. Our findings demonstrate the utility of seismic interferometry in imaging a small scale feature with a size of less than 10 km.

► We investigated the internal structure of Asama volcano from ambient noise. ► A low velocity body is found to the west of the summit at 5-10 km. ► The low velocity body is likely to be a magma chamber. ► Size of the magma chamber should be smaller than 10 km in diameter.