April 25, 2017
A swarm of magnitude ~5-6 earthquakes offshore Chile on April 23 was punctuated two days later by a much larger M6.9 earthquake yesterday evening. While nobody could have specifically predicted the size and timing of this earthquake, it is a terribly unsurprising event, occurring as it did in the midst of this swarm of heightened seismic activity, and in the highly seismically hazardous region of coastal Chile. As has been pointed out by several researchers on Twitter and via the Temblor.net blog, this event occurred within a “seismic gap” along the subduction zone, between the two major recent ruptures in 2010 (M8.8 “Maule”) and 2015 (M8.3 “Illapel”), but it by no means has filled that gap, which will require a much larger earthquake to eventually occur.
— Jascha Polet (@CPPGeophysics) April 25, 2017
— Robin Lacassin (@RLacassin) April 24, 2017
Because the earthquake struck a developed country in the early hours of the evening, there were plenty of cameras at the ready to record the shaking live in the waning daylight. It’s thus exceptionally well documented in videos that are now on YouTube. Here’s my run-down of some of the most illuminating clips captured by eyewitnesses. Chile is no stranger to earthquakes, and I’ve posted collections of YouTube videos of several other large Chilean quakes recently… but these YouTube video links tend to have a limited lifespan, so here we go with a new set of frightening/illuminating/chilling/instructive/charming eyewitness videos of shaking in Chile.
First off, although strong, the shaking on land wasn’t particularly severe thanks to the quake’s location out offshore on the subduction interface beneath the ocean. It was also relatively short duration compared to other recent earthquakes in Chile, its magnitude of 6.9 being about 4% the size of the magnitude 8.3 in 2015, and just over 1% the size of the gargantuan Maule earthquake of Feb 27, 2010. Nonetheless strong shaking can be fearsome to people and animals alike:
— pablo araya (@Pabloarayasw) April 24, 2017
Moderate to strong shaking impacts this quiet living room, alarming more dogs:
The shaking is similarly notable but modest in this office in central Chile:
Pretty strong but undamaging shaking is seen in this home office in Santiago:
…and in this household’s security cameras:
…but contrast those with moderate to strong shaking in a kitchen full of dishes on unsecured shelves, and you begin to get an illustration of how circumstance & surroundings play a big role in how you perceive the intensity of an earthquake:
Similarly, the shaking is much more audible in a big-box store full of housewares:
Of course, being on the upper floors of a swaying high-rise can greatly amplify the shaking. Despite a great deal of well warranted alarm, Twitter user @JSantgo maintains a sense of humor about being hurled around on his upper floor balcony:
Jorge illustrates one thing that’s nearly ubiquitous in videos of earthquakes in Chile: the calm. Even in a rather alarming place to experience an earthquake, these Metro subway riders aren’t panicking as the subterranean platform rattles:
There’s also relative calm in a shopping mall even though it’s roaring with noise from the quake:
This culture of calm in the face of ground-shaking–the ‘Chilean Tranquilo’ I call it–is remarkably universal feature of these videos; you can pretty much always count on hearing calls for calm in an earthquake video from Chile, in contrast to pretty much everywhere else on Earth where the rest of us more or less just gratuitously shout, “earthquake!”
Here a Chilean videographer (/the uploader) openly mocks a visitor to Chile for not maintaining his cool during the shaking. Read/translate the description on youtube:
I speculate that the cool nerve of Chileans in part stems from the remarkable frequency with which they experience strong shaking; it is also made possible by their hard-earned confidence that strict building codes are protecting them from life-threatening structural failures. But the ubiquitous habit of exclaiming, “tranquilo, tranquilo,” or calling to “mantenga la calma” must stem more immediately from simple cultural exposure. Indeed, in a number of these videos we see radio and TV personalities, caught live on air during the earthquake, calling for calm among their whole broadcast audience–a fascinating response to consider for societal response to an earthquake:
…In fact you can see how effective this response is, as clearly the children are imbued with the same habit from a quite early age!
and in what’s newly one of my favorite earthquake resilience moments, a father explains to his fearful son who is asking why it’s shaking so hard, “because we live in Chile.” Listen for the charming moment at 1:40
It’s not all charm and tranquility though, of course. Even this modest earthquake was accompanied by major secondary hazards, including landsliding:
…and a swiftly executed tsunami warning, although fortunately the quake was too small to generate a disastrous wave this time. Videos that show public sirens sounding within seconds of the shaking are a testament to Chile’s commendable preparedness for their very real tsunami hazards. Haunting as it is, the efficient evacuation of coastal areas shown here is immensely gratifying to see. I always find civil warning sirens to be among the eeriest sounds on the planet, as they represent a dire official warning of imminent danger, but that means they’re working. These videos give me chills as you see a population that’s just been shaken running for the hills as warnings of danger echo across their cities before the real scope of the disaster has been realized or understood, but it shows a disaster readiness that all tsunami-prone regions should strive for. Lots of real-life drills in Chile.
“¡Alerta de tsunami! ¡Alerta de tsunami! ¡Prepararse! ¡Prepararse!”
This man feels the earthquake strongly on the beach and begins leaving himself before the sirens sound. Good public education.
So another large earthquake in Chile has left us with a rich little collection of eyewitness videos to inform our own preparation for these phenomena elsewhere in the world. I’ll leave you all with this one, as we might find a kindred spirit in this little girl who, in the safety of a well built house and inspired by her evidently geologist parents, finds awe in the experience of–I’m not even trying to be cheesy here, she said it–the trembling Earth. “Me gusta… eso que tiembla.”