We are pleased to welcome Professor John Spray who will be delivering a seminar on: Hypervelocity impact effects on Earth - Causes and consequences.

Abstract:

Hypervelocity impact effects in our Solar System are now widely appreciated as having contributed to fundamental planet-building and planet-modifying processes throughout geological time. The strain rates at which impact events take place and their duration are exceptional relative to most geological processes with which we are familiar. Hypervelocity impact can cause intense shock loading resulting in melting, vaporization and even plasma formation in target rocks. Further from the contact and the compression locus (<50 GPa), shock waves cause local melting and solid-state phase transformations with the creation of new structural states and mineral polymorphs. An overview will be presented with emphasis on terrestrial impact cratering. Approximately 200 impact structures are now proven on Earth, which is a shadow of its true historical record. This paucity of craters is due to Earth being an active planet, with the majority having been erased due to plate tectonics, volcanic activity, erosion and burial. Nevertheless, valuable examples have survived: we will tour some of these and explore the products of hypervelocity impact as we strive to understand these extreme processes. The seminar will also consider the future and what threats are posed to our social infrastructure by asteroids and comets colliding with Earth.

Biography:

Professor John Spray is Director of the Planetary and Space Science Centre at the University of New Brunswick in Canada. He currently manages a research team of 8, comprising research scientists, engineers, post-graduate students and staff. The team’s research activities focus on investigating planetary materials, frictional melting, impact cratering mechanics, the geology of the Moon and Mars, and processes associated with hypervelocity impact and shock effects. John received his BSc in Geology from Cardiff University and his PhD in Earth Sciences from Cambridge University. He held the Canada Research Chair in Extreme Deformation and Planetary Materials from 2006-2018. He is a co-investigator on the science teams for NASA’s Mars Science Laboratory (MSL) and the ESA’s ExoMars missions.

All staff and students welcome.