Wolfson Plans & Prospects 2019

Earthquakes, elephants, and extraterrestrial life
Good vibrations:
of earthquakes,
elephants, and
extraterrestrial life
At this year’s London Lecture, Tarje Nissen-Meyer introduced his audience
to seismology’s wide range of applications, including the ability of elephants to
communicate via vibration in the Earth’s surface.
Vibrations are everywhere.
Whether signals from deepest
space, telecommunications,
human conversations or
volcanic tremors, waves encode
information about every aspect
of our lives, planet and universe.
Seismology, the study of
deciphering earthquake-triggered
waves, has come a long way from
determining earthquake locations,
their hazard and Earth’s interior.
Owing to recent developments in
instrumentation on land, sea, and
above, big datasets, numerical
techniques, supercomputing and
machine learning, we can now
extract novel information from the
most complex vibrations which
continuously excite our planet,
covering scales from molecular
motions to Earth’s tides.
At Wolfson’s London lecture, I
attempted to convey a diverse range
of novel seismological avenues:
Can we determine the chance of
extraterrestrial life deep inside Jupiter’s
icy moon Europa by analysing tidal
cracking? Can we estimate remote
landslide activity in real-time without
being anywhere near? Can we find
ancient hurricanes in the seismic
record? Can machine learning on
ancient scripts from Persia help in
better understanding earthquake
cycles? What is the role of glacial
calving in ice-sheet depletion and
sea-level rise? Are there Marsquakes?
What is the underlying process behind
three-dimensional cat-scan images
of the Earth’s ‘brain activity’, or
mantle convection, for instance water
deep inside the Earth? What is the
psychological aspect and subjective
bias in interpreting such tomographic
images? And last but not least, do
elephants communicate seismically
over many kilometres? Can our
techniques discriminate their behaviour
much like one earthquake from another
in real-time, and help in combatting
poaching? The common denominators
between these questions are seismic
vibrations that contain cues about the
underlying nature of the corresponding
process, to be recorded with evermore
sensitive seismic instruments
which nowadays record ground
vibrations down to molecular scales.
Seismic data are vast, complex, and
irregular, and cover a vast range of
resolutions and frequencies. Rather
than focusing on big (and often
duplicate) data, seismologists often
hunt for faint, precious observations
bearing valuable information, such as
those rare waves carrying structural
information from the centre of the
Earth, or any clue on past seismicity
to assess the seismic recurrence
cycle. In this context, I argued that
modern methods of data mining may
aid in collaborating with archives and
collections of ancient manuscripts to
find hints on earthquake occurrences
throughout human history. With
seismic recordings barely covering
more than a century, earthquake
cycles of thousands of years require
further evidence from the past to
assess whether geological faults may
yield in the “foreseeable” future.
4 . WOLFSON COLLEGE OXFORD . PLANS & PROSPECTS . 2019