Disputas og prøveforelesning er i Auditorium 1 i Geologibygningen. I noen tilfeller vil prøveforelesning og disputas være mulig å delta på digitalt, i så fall blir det lagt ut en lenke til Zoom.
Prøveforelesning
Tirsdag 1 september, 10:15-11:00, Aud 1, Geologibygningen:
Deep earthquakes: observations, mechanics and remaining mysteries
Kreeringssammendrag
Dypt nede i jordens kontinentale skorpe går bergartene gradvis fra å bryte brått ved bevegelse, slik som ved jordskjelv, til å flyte sakte og jevnt. I sin avhandling brukte Erina Prastyani avansert røntgenavbildning og akustisk overvåking for å se og lytte, i tre dimensjoner, hvordan bergartene sprekker, deformeres og danner hulrom når de går gjennom denne overgangen. Hennes funn tyder på at disse prosessene kan la væsker bevege seg gjennom skorpen, og dette kan bidra til å forklare langsomme, lydløse deformasjoner på dybder der jordskjelv slutter å forplante seg.
Hovedfunn
Populærvitenskapelig artikkel om Prastyanis avhandling:
Microcracking in rocks may create pathways for deep fluids and explain slow earthquakes
Deep within the continental crust, rocks slowly deform under enormous pressure and temperature. Scientists have long thought that, at these depths, rocks become so compact that fluids can no longer move easily. However, geophysical observations suggest that fluids are still present and may contribute to slow earthquakes and the formation of valuable mineral deposits. How this occurs has remained unclear.
In her doctoral work, Erina Prastyani combined high-pressure laboratory experiments with powerful synchrotron X-ray imaging and acoustic monitoring to observe how rocks deform in real time. These experiments allowed both visible cracking and otherwise silent deformation processes to be closely monitored as they developed in a laboratory setting.
Under conditions representing the shallow crust, damage begins when many small cracks throughout the rock progressively concentrate and localize into through-going faults capable of generating earthquakes. At higher pressures, representing the transition toward more ductile behavior in the crust, deformation remains distributed throughout the rock. Instead, the rock develops connected void networks with up to 18% porosity. These transient pore networks may provide pathways for fluids to circulate even at depths where rocks were previously thought to be impermeable.
The findings and knowledge about microcracking in deep rocks in a laboratory setting may improve our understanding of slow earthquakes, mineral-forming processes, and the long-term potential of deep geothermal energy.
This doctoral work is done at Department of Geosciences and the Njord centre, and the lab experiments have been carried out at research facilities at the European Synchrotron Radiation Facility (ESRF) in France, and the GFZ Helmholtz Centre for Geosciences in Germany.
Foto og annen informasjon:
Pressefoto: Erina Prastyani, portrett; 2000px. Foto: Privat
Annet bildemateriale: Figur med beskrivelse og kreditering som spesifisert i artikkelen over, størrelse 1200px.