Magnitude 8.3 earthquake, central Chile, 16th September 2015

USGS Shakemap: available here

A great earthquake struck central Chile yesterday, with severe to extreme shaking felt in the Coquimbo region. The initial magnitude is estimated at 8.3, making this larger than the 2014 Iquique earthquake and the largest to strike Chile since the magnitude 8.8 earthquake of 2010.

The earthquake occurred along the Chilean Subduction Zone, a fault between the Nazca and South American Plates. The Nazca Plate subducts beneath South America, with the strain that accumulates over time episodically released during earthquakes. Great subduction zone earthquakes such as this are accompanied by intense shaking that may last several minutes. They also frequently generate tsunamis, which may be damaging both close to the source and across ocean basins. Wave heights of over 4m have been reported in Chile. The Pacific Tsunami Warning Centre suggests large waves are unlikely for most Pacific countries, however Chile and French Polynesia remain on alert for waves exceeding 1m.

So, what happens when a giant tsunami inundates coastal lakes?

This blog post is by Philipp Kempf, PhD student at Ghent University, who writes about his recently published Sedimentary Geology paper on tsunami deposits in coastal lakes in south central Chile. Philipp is now on twitter too, tweeting as @TsunamiPhil.

Pan Pacific Palaeoseismology symposium

Last week I was delighted to welcome fellow academics, friends and collaborators from Potsdam Universty, Ghent University, Durham University and The Geological Survey of Belgium to join me for a symposium on subduction zone palaeoseismology. The day-long meeting was an opportunity to present and discuss the different approaches that we use when studying past earthquakes, tsunamis and subduction zone behaviour.

The 1877 and 2014 earthquakes

We provided a brief introduction to the 1st April 2014 Iquique earthquake earlier. It's struck the Northern Chilean (or Iquique) seismic gap, an area that hasn't ruptured in a major megathrust earthquake since 1877 (though a magnitude 7.7 earthquake did rupture a deeper section of the interface in 2007). GPS data published in 2004 suggested the Nazca and South American plates were fully coupled, with none of the plate convergence being offset by slip between the plates. An update just last year identified three zones of high coupling - the Camarones, Loa and Paranal segments - separated by weaker zones. Potentially any of these segments would individually be capable of producing an earthquake of the size of the one seen yesterday. The authors

Magnitude 8.2 earthquake north of Iquique, Chile, April 2014

A major earthquake struck the north of Chile yesterday (1st April 2014), with intense shaking felt in the cities of Iquique and Arica. Less intense shaking was also felt across northern Chile and in Bolivia, Peru, Brazil and Costa Rica..The USGS maintains 'did you feel it?' pages, where anyone can report shaking that they have experienced. Here's the page for the 1st April earthquake: Did you feel it?. Initial reports placed the magnitude in the region of 8.0, with subsequent analysis upgrading this to 8.2. This USGS page will continue to be updated as further information on the earthquake becomes available. For comparison, the 2010 Maule (Chile) earthquake measured 8.8, the 2011 Tohoku (Japan) earthquake registered

Recent magazine article highlighting our work

While we've been busy on fieldwork and analysing the sediments we've collected, we're also keen to keep publishing our findings and updating people on where we're at with our research. Back in September our first academic paper on Chilean earthquakes was published in Quaternary Science Reviews. This month we've written an article in International Innovation magazine, produced by Research Media Ltd. The Environment issue of this magazine disseminates current global environmental issues to the wider

Coring, coring, coring (+Videos)

Much of our last field season was spent coring tidal marsh sediments. See previous posts for more details on what we do both in the field and back in the labs. In order to sample sediments several metres below the ground surface we use a sediment corer - either a gouge corer (for reasonably consolidated sediments) or a Russian corer (in peats or more unconsolidated sediments). Here is a short video showing us using a gouge corer at Chaihuin, with the invaluable help of Bill Austin from St Andrews University.