“Terrestrial Planetary Seismology” with Philippe Lognonné (Institut de Physique du Globe de Paris, France)

Seismology is the ultimate tool for exploring the interior of planets but is technically extremely challenging as it requires the careful installation of highly sensitive sensors in an environment that is not always supportive. On the Earth, a large number of seismic stations and arrays has made a detailed tomographic mapping of the interior possible that even allows the imaging of the deep driving elements of surface plate tectonics and the detailed topography of e.g., the core mantle boundary. An array offour seismic stations has been operating for almost a decade on the lunar surface until it was shut off in 1977 and provided a wealth of data that is being studied even today by planetary seismologists. In 2018, the NASA InSight mission brought a highly sophisticated seismometer to Mars with three very broad band sensors and three sensors optimized short period signals. Because InSight is a single station – three stations are conventionally needed to locate a quake with travel times only – planetary seismologists adopted their inventory of interpreting tools to extensively use the data and compensate for the lack of additional stations. The method uses the individual runtimes of compressional, shear and, if detected, surface waves all generated by the same quake. Almost continuous monitoring of the seismic activity of Mars has confirmed that the planet is intermediate in activity between the larger Earth and the smaller Moon. The interpretation of the data has allowed to provide a layering in the crust underneath the landing site and is now constraining deeper structures, including the temperature profile in the mantle and core. The talk will be concluded on the future perspectives of planetary seismology in term of new mission toward the Moon, icy satellites and other terrestrial planets including Venus and Mars.


Philippe Lognonné is professor of planetary geophysics at the Université de Paris and perform his research in the Institut de physique du globe de Paris. He is a senior honorary member of the Institut Universitaire de France and a fellow of the American Geophysical Union. He is the instrument Principal Investigator of the SEIS experiment on the NASA InSight mission to Mars.


This webinar was recorded on May 27, 2021