The Next BIG Earthquake?
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The recent earthquake tragedies in Iran and Iraq that killed 400 people last Sunday may come as no surprise to some as fault lines run through Iran and Iraq, so their recent earthquake should come as no surprise. However, the 7.3 magnitude is much higher than the 2012 6.4 and 6.3 quakes that killed 300 people.
The rural regions are especially hard hit with mud-brick homes collapsing and kerosene heater and lamps igniting fires. There were even mudslides triggered by aftershocks creating a chaotic situation amidst the suffering. Iranian officials said 70,000 people are homeless.
This is a big reminder to us all around the world but perhaps especially to those living in the Pacific Northwest where the next "big one" is expected to cause a catastrophe of epic proportions.
Let's take a look at the anatomy of earthquakes
1) Invisible Origins
When our Earth's huge underground tectonic plates grind into each other, we experience shaking above ground. The electromagnetic forces churning at around the core of the planet cause these shifts, which occur gradually all the time until some pressure points build to a dangerous crescendo.
The tectonic plates can slide over and under each other or slide across each other along fault lines.
“Our understanding of these within-plate earthquakes is not as good,” said Stanford University geophysics professor Greg Beroza. “These two earthquakes that happened in Mexico are the latter,” he added, noting that an earthquake within a tectonic plate has fewer telltale signs than those that occur at fault lines.
2) Measuring Earthquakes
The Richter Scale was invented in 1935 by Charles Richter and uses a logarithmic scale, rather than a linear scale. A logarithmic scale shows a magnitude 7 earthquake as 10 times stronger than a magnitude 6, and 100 times more than a magnitude 5.
However, it's actually a very limiting perspective as it only measures the peak of an earthquake's seismic waves. It misses the size of the triggering force and the radius of the affects.
“We can’t use that in our design calculations,” said Steven McCabe, leader of the earthquake engineering group at the National Institute of Standards and Technology. “We deal in displacements.”
Displacement of the ground it another method.
Moment Magnitude Scale measures different seismic waves with precise instruments but is just a size proxy of the earthquake. It can take up to a year to calculate a quake because of indirect measurements.
Peak Ground Acceleration measures speed and directional changes.
3) Predictability
There are many more wrong earthquake predictions than accurate ones but geologists have identified the fault lines where earthquakes tend to recur. See US Geological Survey’s interactive map of fault lines and NOAA’s interactive map of seismic events. So we know where but not when.
Also, there are usually smaller tremors following large earthquakes. Countries are setting up electronic warning systems to buy a few minutes that can save lives.
4) Natural or Manmade Disasters?
Besides naturally occurring earthquakes there are some triggered by manmade hydraulic fracturing or the injection of millions of gallons of wastewater underground. This makes it easier for tectonic plates to move at fault lines.
US Geological Survey map of natural and induced earthquake risk in 2017.
The US Geological Survey reported Oklahoma earthquakes exploded to 2,500 in 2014, 4,000 in 2015, and then down to 2,500 in 2016.
“The decline in 2016 may be due in part to injection restrictions implemented by the state officials,” the USGS wrote in a release. “Of the earthquakes last year, 21 were greater than magnitude 4.0 and three were greater than magnitude 5.0.”
Usually, there are only two quakes a year at magnitude 2.7 or greater.
It Pays to Prepare
90% of earthquakes happen in the Ring of Fire around the Pacific Ocean that runs through the Philippines, Japan, Alaska, California, Mexico, and Chile. Oh yeah, 75% of all volcanoes are located here too, sounds cozy right?
After years of experiencing the devastation of earthquakes in crowded cities with tall buildings, engineers and architects learned to seismically retrofit old buildings and quake-proof new ones. This, of course, costs more so some people are resistant to implementing these changes. It's almost certainly worth the price to save lives in the future.
A terrible example of poor building code is the 150,000+ deaths in Haiti's 2010 magnitude 7.9 quake.
The "Big One" is Coming
The New Yorker won a Pulitzer Prize in 2015 for reporting the potential massive earthquake in the Pacific Northwest — “the worst natural disaster in the history of North America,” affecting 7 million people over 140,000 square miles.
It could be a magnitude 8.7 up to 9.2, even bigger than the San Andreas Fault's expected max of 8.2.
“In the business, we’ve been talking about that [Pacific Northwest] scenario for decades,” Beroza said. “I wouldn’t say we’re overdue, but it could happen at any time.”
Since it's better to be safe than sorry, please consider preparing. Let the recent earthquakes around the world be reminders of the serious risks earthquake-prone regions face.
Sources:
https://www.vox.com/platform/amp/energy-and-environment/2017/9/21/16339522/8-things-to-know-about-earthquakes-mexico
