A 7.1 magnitude earthquake struck Mexico City on Tuesday, September 19, collapsing buildings, killing at least 250, and injuring hundreds more throughout the region. The latest tremor event came hard on the heels of an 8.1 magnitude quake off the coast just 2 weeks ago, which killed almost 100 and even generated a small tsunami wave. Various aftershocks measuring up to 4.9 have been recorded since Tuesday’s quake hit at 1 pm local time.
Although there is no “season” for earthquakes like there is for hurricanes, yesterday’s tremors occurred on the exact date that a 1985 event killed close to 10,000 Mexicans in the capitol.
The United States, especially (but not exclusively) the West Coast, is also susceptible to natural disasters like earthquakes. Indeed, just a few days ago, citizens in Los Angeles experienced 3.6 magnitude tremors, but no deaths or major damage was reported.
FAULT LINES AND MAGNITUDE SCALES
The West Coast and some areas of the Midwest are located over what we call “fault lines“. A fault is a fracture in a volume of base rock in the earth’s crust. Mexico City itself is not located on a fault line, but sits on an old lake bed that amplifies nearby tremors. This disrupts buildings that were constructed on the surface, making them prone to collapse.
Earthquakes have been blamed on climate change by some, but the movement of the earth’s plates occurs miles below the surface. This shifting releases a tremendous amount of energy, sometimes referred to as a “seismic wave”.
The strength of the Mexican earthquakes have measured using something called the “Richter scale“. This measurement (from 0-10 or, theoretically, more) identifies the magnitude of tremors at a certain location. Quakes less than 2.0 on the Richter scale are common occurrences unlikely to be noticed by the average person. Each increase of 1.0 magnitude, however, increases the strength by a factor of 10. The highest-intensity earthquake ever recorded was The Great Chilean Earthquake of 1960 (9.5 on the Richter scale).
Most people have heard of the Richter Scale and assume that all earthquakes are measured using it. However, a newer measurement, the Moment Magnitude scale, is thought to be more accurate for higher intensity quakes. The Moment Magnitude scale calculates each point of magnitude as releasing more than 30 times the energy of the previous one.
If the fault lines shift offshore, a “tsunami” or tidal wave may be generated. In Fukushima, the 2011 earthquake (8.9 magnitude) spawned a large tsunami which caused major damage, loss of life, and meltdowns in local nuclear reactors. Tsunami warning were issued for both the Japanese and Ecuadorian earthquakes reported this week. The tsunami generated by the quake 2 weeks ago off the coast of Mexico was only 2.3 feet, however.
AN EARTHQUAKE SURVIVAL PLAN
A major earthquake is especially dangerous due to its unpredictability. Although researchers are working to find ways to determine when a quake will hit, there is usually little warning. This fact makes having a plan of action (before an earthquake hits) a major factor in your chances of survival.
This plan of action has to be shared with each family member, even the children. It’s unlikely that a disaster will occur at the moment that the entire clan is together. Unless the earthquake happens in the dead of night, it’s unlikely everyone will be together in the house. You might be at work, your spouse at home, and the kids at school. An important part of an earthquake survival plan is making everyone aware of where to meet. It could be your home, or perhaps more sturdy public buildings like a school or office building that might be earthquake-resistant. In any case, knowing where to meet in the event of (really, any) disaster will give you the best chance of gathering your family and surviving together.
To be prepared, you’ll need, at the very least, the following supplies:
- Food and water (including water filters like the LifeStraw, Mini-Sawyer, and Katadyn)
- Power sources like batteries, solar rechargers, and generators
- Medical supplies and medicines
- Tents, sleeping bags, and other camping equipment
- Clothing appropriate to the weather
- Fire extinguishers
- A tool kit, including an adjustable wrench to turn off gas, water, etc.
- Means of communication like cell phones, walkie-talkies, radios
- Cash! (don’t count on credit or debit cards if the power’s down)
- Copies of important documents, including insurance policies
(these supplies are discussed in detail in the latest edition of The Survival Medicine Handbook: The Essential Guide for When Medical Help is Not on the Way.
In areas at risk for earthquakes, the school system and municipal authorities usually have formulated a disaster plan. They may even have designated a quake-proof shelter; this may be the best place to go. Make certain to inquire about your town’s precautions in case of a seismic event.
Besides the general supplies listed above, it would be wise to put together a separate “get-home” bag to keep at work or in the car. Nonperishable food, liquids, and a pair of sturdy, comfortable shoes are useful items to include in this kit.
HOME EARTHQUAKE SAFETY
In the home, it’s important to know where your gas, electric, and water main shutoffs are. Make sure that everyone of age knows how to turn them off if there is a leak or electrical short. Know where the nearest medical facility is, but be aware that you may be on your own; medical responders are going to be overwhelmed and may not get to you quickly. In addition, roads may be impassible due to damage or traffic snarls.
A good look around your house might identify fixtures like chandeliers and bookcases too unstable to withstand an earthquake. Examine cabinets for heavy objects on high shelves, and replace them to bottom shelves where they will help with stabilization.
In the family room, flat screen TVs, especially large ones, could easily topple. Be sure to check out kitchen and pantry shelves for glass objects or pots and pans that could topple. In the bedroom, check the stability of anything that might be hanging over the headboard of your bed and could fall on you as a result of a nighttime quake.
WHEN THE EARTHQUAKE HITS
What should you do when the tremors start? When things start shaking, you’ll have to keep a cool head and, if indoors, get under a table, desk, or something else solid and hold on. Cover may protect you from falling objects. This strategy is called “Drop, Cover, Hold“. If hard cover isn’t available, even a mattress could serve as a shield. If no cover is available at all, considering heading to the corner of an inside wall.
Of course, you might choose to run out of the building. You’re more stable, however, on your knees than standing or running, so get down to prevent a fall from causing injuries. While the building is shaking, don’t try to run out (especially if you’re on an upper floor); you could easily fall down stairs or get hit by falling debris. Don’t try to use elevators. You should stay clear of windows, shelves, and kitchen areas.
It’s often taught that you should stand in the doorway because of the frame’s sturdiness. It turns out, however, that in modern homes, doorways aren’t much more solid than any other part of the structure. Even if it were, you could still get hit by falling objects.
Once the initial tremors are over, go outside. Once there, stay as far out in the open as possible, away from power lines, chimneys, walls, and anything else that could fall on top of you.
IN YOUR CAR
You could, possibly, be in your automobile when the earthquake hits. Get out of traffic as quickly as possible; other drivers are likely to be less level-headed than you are. Don’t stop your car under bridges, trees, overpasses, power lines, or light posts. They’re likely to topple in a major quake. Stay in your vehicle while the tremors are active; turn on the radio to find out more about the event.
AFTER THE EARTHQUAKE
Even after the tremors stop, there are still dangers. Gas leaks are one issue to be concerned about; make sure you don’t use your camp stoves, lighters, or even matches until you’re certain all is clear (and, certainly, never inside). Even a match could ignite a spark that could lead to an explosion. If you turned the gas off, you might consider letting the utility company turn it back on.
Buildings that have structural damage may be unstable or have loose concrete which could rain down on the unsuspecting. Falling stone from damaged buildings killed rescuers in the Oklahoma City bombing and the World Trade Towers collapse.
Power may be down, and many will be tempted to use generators. It’s important that generators are used, not just outside, but well away from the interior of the home. A family of four in Florida after Hurricane Irma was hospitalized when a generator was used outside but too closely to the home’s entrance.
Don’t count on telephone service after a natural disaster. Telephone companies only have enough lines to deal with 20% of total call volume at any one time. It’s likely a much higher percentage of lines will be occupied after a disaster. Interestingly, this doesn’t seem to apply to texts; you’ll have a better chance to communicate by texting than by voice due to the wavelength used.
That cell phone will also come in handy if you’re trapped under rubble after an earthquake. Voice calls or texts might alert rescue personnel to your plight. If you live in quake country, you might consider a whistle on your keychain. It’s loud and will last longer than your voice as a signal for help. Don’t give up if help doesn’t arrive immediately; people can live several days without water, and much longer without food. With any luck, rescuers will find you.
Even if you have been injured, your house, even if earthquake-resistant, will probably require some cleanup. Remember to wear sturdy shoes, work gloves, and protective goggles while you’re picking up after the quake. Enter damaged buildings at your own risk, and look before your step.
Joe Alton, MD
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