Probing the Depths of Long Valley Caldera

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A new study by CalVO seismologists used a novel geophysical technique called "full waveform seismic tomography" to image the roots of Long Valley Caldera in eastern California.

Long Valley Caldera and domes viewed from the top of Mammoth Mounta...

Long Valley Caldera and domes viewed from the top of Mammoth Mountain. Mono Lake visible in upper left of photo.

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The study revealed a zone of low seismic wave velocity >1000 cubic kilometers in volume, of which, an average of 27% may be molten. This partially-molten zone is deep within the crust, below about 10 kilometers, and only small pockets of it may be fluid enough to rise upwards and eventually erupt. Although eruptions as large as the one that produced Long Valley Caldera 767,000 years ago are extremely rare, understanding the volume of melt in the roots of volcanic areas is critical for understanding the potential for future eruptions and for anticipating the hazards that may ensue. [Ashton F. Flinders, David R. Shelly, Philip B. Dawson, David P. Hill, Barbara Tripoli, and Yang Shen; https://doi.org/10.1130/G45094.1