Assembly Speaker, Monday 29 January – Professor Lidunka Vočdlo- Mineral Physicist UCL.
Sixth Form Assembly - Core! What a scorcher!
On Monday, Professor Vocdlo gave a very absorbing talk about the study of the Earth’s Core. She started by breaking down the layers of the earth’s core for us: Crust, Mantle, outer core (liquid), inner core (solid).
Then went on to outline why we should care about it - essentially it all comes down to the magnetic field which protects us from the sun’s rays and solar winds. Also, importantly, the heat generated and sustained within the earth's core, directly affects our earth's surface with the formation of volcanoes and the creation of surface instability which causes earthquakes. Additionally, the study of the core gives us some valuable insights into the earth’s solar system.
Experts have tried to drill as far down as possible into the Earth’s core but this is always hampered by the intensity of heat the further down you go destroying the drilling equipment. She showed us an amazing picture of the deepest hole ever dug which was in Russia, which was 12km deep- this is as deep as we can go with modern day drilling equipment.
Professor Vocdlo, then spoke to us in more detail about the two natural phenomena which give us the most information about the composition of the earth's core: volcanoes and earthquakes. The lava which spills from volcanoes can come from as deep as 200km down.
She explained how earthquakes are formed by plates moving in different directions with different velocities- the plates can collage to form mountains ie volcanoes OR subduction can occur (the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate) which results in earthquakes and tsunamis because of the sudden explosive energy releases.
Apparently, there are 10-100 earthquakes, of varying magnitude, happening on the earth’s surface every day. The most powerful earthquake was the one in Mexico in 1960, which measured 9.5 magnitude which is ‘as big as you can get.’
She explained that, basically, we know that the outer core is a liquid due to earthquakes. The core is extremely hot at 6000 degrees (roughly as hot as the surface as the sun) and has very intense pressure - she used the analogy of 75,000 elephants in stilettos (with a funny visual) to give us an idea of the extreme pressure in the core!
When asked how accurately we can predict earthquakes, she told us that there is lots of data that can tell us about an impending earthquake but we can’t pin it down to a particular time very accurately.
All in all, It was an eye-opening talk and kept us all engaged and interested on a grey Monday morning!
Ella - Senior Prefect