Assessing seismic risks
p. 104-105
Résumé
Particularly devastating earthquakes can occur in Ecuador and Peru. In these countries, knowledge of the areas likely to be hit by earthquakes is a key aspect of public policies in terms of seismic risk prevention.
Texte intégral
1In 1906, Ecuador was struck by an 8.8 magnitude earthquake. This was the world’s fifth most powerful earthquake ever recorded. Over the century that followed, the area was hit by a number of other major earthquakes, three of which had a magnitude of over 7. This frequency explains, among other things, the posting of IRD seismologists to the site. As the region lacked instrumentation, upon their arrival in 2008 they installed 10 measurement stations equipped with an accelerometer, a seismometer and a GPS beacon. The purpose of this instrumentation was to help them describe the tremors, but also the “silent” landslides which can occur on certain faults. Two years later, Ecuador completed the mechanism and now enjoys a modern monitoring network including 85 GPS beacons, 80 seismometers and 120 accelerometers. Measurement stations are used to produce seismic hazard maps.
2By analysing the data collected, in 2014 researchers discovered a previously unknown tectonic plate, which they named “Inca” plate. They also calculated local stress forces and pinpointed the areas most likely to be hit by major earthquakes. The 7.8 magnitude earthquake which occurred in Ecuador in 2016, claiming nearly 700 lives, was located in one of the areas previously identified as dangerous. French and Ecuadorian researchers are now drawing up seismic hazard maps. This crucial information is now available to Ecuadorian policy-makers and institutions to simulate the impact of a seismic event and determine development priorities. Furthermore, these maps have also helped researchers conclude that the next major earthquake may occur in Peru, in the Lima region where more than 12 million people live.
“In Ecuador, earthquakes and volcanic eruptions have constantly affected the country’s population and development. Knowledge of these events and their effects is key to managing risks, devising prevention policies and improving resilience. This knowledge is one of the facets of our institute, and IRD’s contribution was central to the training of specialists and completion of joint research projects. The results achieved significantly enhanced knowledge of seismic and volcanic processes.”
Alexandra Alvarado, director of the Geophysical Institute (2016-2018), Quito National Polytechnic School, Ecuador
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