Geophysics seminar: Emile Okal (Northwestern University) "Nineteen tsunamis from Sumatra (2004) to Tohoku (2011) and beyond (2017): Are we getting wiser?"


 
07/20/2018 - 3:30pm to 4:30pm
Location: 
Munk Conference Room
Event Description: 

Talk abstract:

Since the 2004 Sumatra disaster (250,000 deaths) made "tsunami" a
household expression, no fewer than 18 other substantial tsunamis
have occurred, with the 2011 Tohoku event (19,000 deaths) being
the latest to reach a disastrous level, notably because of the
damage incurred by the Fukushima Dai-ichi nuclear power plant.
We ask the simple question "What have we learned in 13 years?"
and "Have we become wiser?" in areas such as Science,
Engineering, Mitigation and Social Response.

The 2004 Sumatra earthquake took many scientists by surprise, as
then-prevailing tectonic models precluded the occurrence of a
mega-thrust event (with magnitude 9) in its particular
tectonic environment, which featured neither a young oceanic
plate nor a fast subduction rate. Both the 2011 Tohoku event,
and a careful reassessment of several historical earthquakes,
have led to the definitive abandonment of this paradigm, and
a precautionary attitude now regards all sufficiently long
subduction zones as potential hosts of mega-thrust events.
On the other hand, the 2004 Sumatra earthquake has ushered the
era of modern, powerful inversion techniques allowing the
rapid quantification of the long-period spectrum of the source
of large earthquakes, responsible for the generation of their
tsunamis.

We review the operational performance of warning centers and
the response of the populations at risk by assigning, in
the form of a color-keyed "report card", an admittedly subjective
"wisdom index" to each of the 19 tsunamis since 2004. While
several events earned a "green" star through their successful outcomes
(Solomon Islands, 2007, 2010, 2013; Bengkulu, 2007), a number
of "red cards" were issued (Java, 2006; Mentawai, 2010).
The 2011 Tohoku earthquake presents a somewhat typical case,
where warnings and response were adequate in the far field,
but deficient engineering and mitigation efforts in the near
field resulted in enhanced destruction and death. In
particular, the nuclear accident at Fukushima resulted
from a cascade of scientific, engineering, technological,
and human failures, most of which should have been preventable.
The latter illustrate a managerial "insularism", characterized
by an inward-looking attitude within the utility, ignoring
broadly-known aspects of seismology in Japan, commonly
used standards of hydrodynamic simulations, as well as simple
common sense in the definition of worst-case scenarios.

By contrast, the detailed examination of many of the 19
case studies repeatedly stressed the value of education, in all
its forms, as a significant factor of natural hazard mitigation,
an educated population with even moderate risk awareness and
training standing a much better chance of survival during major
tsunamis.

For more information on this event, contact: 
Michael Murphy
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