When the ‘solid’ ground moves

My hubby and I have experienced al kinds of strange phenomena on our travels, and I have to say that an earthquake was the eeriest. We walk around on this earth expecting it to stay put, and when it doesn’t it’s unnerving.

Ontario, the province I live in, experiences very mild tremors from time to time, but every level upward on the Richter scale is incrementally more powerful. The earthquake we were in while visiting friends in California a number of years ago was 4.6, and while no one got hurt, our immediate instinct was to find an aircraft and get the hell off the ground (very different from the way we felt after our aborted flight to Milford Sound in New Zealand years later, when the turbulence was so bad I literally wanted to kiss the ground in relief upon landing).

I can’t even imagine the feeling of a 7.8 quake, which according to the old seismic scale created by Charles Richter and Beno Gutenberg in the 1930s, would be 30 times stronger that the one we went through. Photos in news media, and the enormous loss of life, tell the actual story.

Our minor quake started as a rumble, as if a large truck was coming down the road, and that’s what we thought it was. But instead of passing by the house of our friends, where we were staying, it just seemed to keep coming and coming. One of our friends jumped up to hold the china cabinet in place and keep it from toppling over, which in retrospect was unlikely – but one of the worst things about earthquakes when they begin is you have no idea how bad they’re going to be.

We were warned not to go outside, where those pretty red clay Californian roof tiles tend to pop off like lethal frisbees. The best thing to do was find a part of the house with the most structural integrity, as in a bathroom (all the pipes in the walls) or any cased doorway.

Riding it out, the initial quake felt like it went on forever, but was less than a minute. Our friends were used to it; we were quite freaked out. Then the aftershocks began, and trickled on for hours. Some were very subtle (it was Christmastime, and occasionally we could see the tree ornaments jiggling even though we couldn’t feel anything), others were startling, as if a gigantic creature kicked the house and shifted it a few inches. We had visions of great cracks opening in the ground (thanks, Hollywood!), which didn’t happen at the time, but they certainly have in Turkey.

In Turkey and Syria, it was the buildings themselves that were the danger, by all accounts for one main reason: they hadn’t all been built to code. The quake took place on February 6th, and by the 12th, 113 arrest warrants had been issued to contractors and others in the building industry for failing to follow quake guidelines. According to BBC News, experts in Turkey had been warning for years that many new buildings were unsafe due to corruption in the industry as well as government policies that, in order to encourage a construction boom, allowed contractors to circumvent the regulations. And of course, it’s been largely the innocent public who’ve paid the price, over 30,000 of them dying in Turkey and more than 5,000 in Syria as rescuers work frantically to try and recover them under hundreds of pounds of rubble.

Earthquake-proofing a building, or a city, has been studied extensively since the famous San Francisco quake in 1906. Little was known about the mechanics and geology of earthquakes in that time. Based on modern scales that have superseded the Richter model, the quake was likely around 7.9 – a major shake that flattened buildings never meant to withstand such stresses.

San Francisco Earthquake of 1906: Ruins in vicinity of Post and Grant Avenue. Looking northeast. By Chadwick, H. D – This tag does not indicate the copyright status of the attached work. A normal copyright tag is still required. See Commons:Licensing., Public Domain, https://commons.wikimedia.org/w/index.php?curid=2128556

To make matters worse, fires broke out all over the devastated city, and the water supply for fighting them wasn’t up to the task.

San Francisco, and all of California, lie along the enormous San Andreas Fault, 750 miles of trouble. Californians straddle the geographic wrestling match between the world’s two largest tectonic plates:

the Pacific Plate (covering almost the entire bottom of the Pacific Ocean, 40 million square miles), which is moving steadily in a northwest direction, and the North American Plate (29 million square miles, covering most of North America, down into the Caribbean and eastward across a good portion of the Atlantic Ocean), which is moving southwest but is forced into a southeastward direction by its massive neighbour. Photos of the Fault look like a nasty scar on the landscape.

Aerial photo of the San Andreas Fault in the Carrizo Plain; By Ikluft – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=3106006

The earthquake in Turkey and Syria occurred along the fault between the Anatolia and Arabia Plates, with the top edge of the Africa Plate just a short distance south. The two major fault lines created by this juxtaposition, have a slip rate of 1/4 inch to almost 1/2 inch a year. The San Andreas Fault’s slip rate is substantially greater, at more than 3/4 inch, but California’s building codes are much stronger.

So how does one make a building as quake-proof as possible?

Well, I can tell you that the Incans in Peru did it quite well. The Spanish invaders regularly built their churches and other buildings on top of Incan walls – and when the next earthquake came along, the Spanish structures fell down and went boom while the Incan constructions remained serenely intact. The 2007 earthquake in Peru, along the central coast, measured 8.0. In the town of Pisco, right in the middle of the quake, you can see how it damaged an old church on the town square, to the point where the building became unusable and a new church had to be constructed beside it. Fortunately, the fast-moving Nazca and South American Plates (3 inches per year), stayed put while we were there, and the only shaking anyone might have felt was after a few stiff Pisco Sours.

The secret of Incan construction was huge stone blocks interlinked with holes matched up with protrusions that locked the walls together. Their civilization was brilliant at creating long-lasting structures.

Incan wall showing remnants of the original construction details – protrusions and holes that fitted together to lock a wall into place, taken at the Museo Inka in Cuzco, Peru – E. Jurus,all rights reserved

For modern buildings, keeping them standing during a quake depends on the size of the building. Average wood-framed homes in California can apply to be retrofitted to make them sturdier. The “Earthquake Brace + Bolt (EBB)” system involves bracing any ‘cripple’ walls (walls 4’ or less between the frame and the foundation) in the crawl space under the house (no basements in California) with plywood sheaths to strengthen them, and then using large anchor bolts to connect the wooden frame to the concrete foundation. It’s all designed to keep a house from sliding off its foundation during a quake. The retrofit also straps in the home’s water heater, which can tip over and damage water lines, gas lines and electrical wiring. Contractors have to be trained by FEMA (the U.S. Federal Emergency Management Agency).

Multi-storey buildings have their foundations put on what’s called ‘seismic base isolation, using isolator bearings of layers of rubber and steel with a lead core. These reduce the amount of vibration a tall building experiences. It’s remarkably effective – you can watch a video demonstration here. Buildings may also contain steel-plate shear walls and other damping materials that reduce the lateral movement of the structure.

Something like 80% of all the major earthquakes on Earth occur around the volatile Ring of Fire – basically the edges of the Pacific Plate. Here in Canada, it’s lovely British Columbia that suffers the brunt of the Ring of Fire’s ire. Our government’s website has information and instructions on what to do should you find yourself in the throes of a good shake.

  • If you’re inside, stay there and “Drop, Cover and Hold On” – drop under sturdy furniture like a desk or a bed, cover your head and torso to protect against falling objects, and hold on tight to whatever you’re under.
  • Stay away from windows and shelves with heavy objects.
  • If you can’t find something strong to hide under, crouch or flatten against an interior wall.
  • If outside, stay there and move away from any buildings BUT if in a crowded place find some cover so you’re not trampled.
  • If in a vehicle, pull over safely and avoid blocking the road. Avoid anything that could collapse on or underneath you, like bridges and overpasses/underpasses. Stop the car, stay inside, and listen to the radio for emergency instructions.
  • In general, avoid: doorways with doors that might slam shut and hurt you; bookcases and other tall furniture that can easily fall over on you; elevators; coastlines (tsunamis are triggered by earthquakes).

The site also has instructions on how to make your home as safe as possible if you live in an area prone to substantial quakes, and what to do after the quake has happened.

It took my hubby and I thirteen years to work up the nerve to return to California (if you knew our track record with bizarre travel adventures you’d understand), but we’ve been several times since and – to date – haven’t experienced another one. We were also lucky in Peru just a few years after the 2007 quake and in New Zealand (which just had a 6.1 quake on February 13th), where we watched the city of Christchurch on South Island still rebuilding from two bad quakes in 2011. Is our luck running out? We may find out in British Columbia when we visit for Storm Season – not sure when, but it’s on my bucket list.