How did the Haiti Quake Compare to the Chile Quake? Crunching the Numbers.

Dear CF,

It seems that the Internet is as confused by all that’s happened as we are. I want to address a question that seems to be oozing out of every news story:

How does the Chile quake compare to Haiti’s?

Everyone is scrambling to frame the Chile earthquake in terms of the Haiti one. It’s a misguided but understandable impulse—at the moment I suppose it’s the most immediately available tool for comparison. It should go without saying that the comparison is basically misguided: Chile has a long experience of earthquakes, a developed infrastructure, and a comparatively favorable colonial and economic history—all things that Haiti lacks.

Still, attempts to make the comparison have been made, and
they’re confusing, even at the numbers level. So I think it’s worth spending some time setting the record straight about what these figures can and can’t tell us.

The Confusion: 50x as great? 100x? 500x?

Sometimes accounts of the Chile earthquake sound like a bidding war. According to the Miami Herald, “the energy released is between 500 and 900 times that of the magnitude 7.0 quake that hit Haiti on Jan. 12 …. On the complex scale that measures earthquakes, an 8.0 quake releases 30 times the energy of a 7.0, and a 9.0 would release 30 times that, meaning 900 times more energy. An 8.8 would be somewhat less, Dixon said.”

According to AP/CBS News: “The 8.8-magnitude earthquake that struck Chile early Saturday morning released 500 times the energy of the 7.0-magnitude quake that struck Haiti last month, a geophysicist told CBS’ “The Early Show.””

Other sites are claiming that the Chile earthquake was 50 or 100x more powerful than the Haiti quake.

So, how do we account for the discrepancy in these figures?

What the Moment magnitude scale (and the Richter) do and don’t mean

I spoke with Dale Grant at the U.S. Geological Survey to get some help. Grant explained that neither the Richter scale nor its more advanced cousin, the Moment magnitude scale (in which current earthquake ratings are reported) account for energy released during a quake—that has to do with several variables like depth, location and geology, and can at best be estimated, even using the Mms. The Richter scale, now out of use, measured amplitude alone, and was therefore only useful as a measure of the magnitude of difference.

The Moment magnitude scale, Richter’s better multitasking cousin, is better at tracking the relationship between amplitude and energy, but it’s far fro perfect. Like the Richter scale, the MMS is logarithmic, where an earthquake one whole number greater has 10 times the amplitude and has approximately 31.6 times more energy. For example, M7.0 has about 31.6 times the energy of M6.0, and 1000 times the energy of M5.0.

This is where those differences in the figures reported are coming from. Some are comparing amplitude; others are comparing energy released.

What these figures can tell us:

Again, the difference between integers (say, 7 to 8 ) represents a 10x difference in amplitude. Therefore the difference between the Haiti quake (for convenience, we’ll call it 7) and the Chile quake (for convenience we’ll call it 9) is 10 x 10=100. This means that the Chile quake was roughly 100 times more powerful than the quake in Haiti.

Again, according to the Moment magnitude scale (which is logarithmic) the difference between integers represents an increase of 31.6x energy released. This means that a difference of two integers (7 to 9) means 31.6 x 31.6=998.6, so the Chile quake probably released *approximately* a little less than 1000x as much energy than the Haiti quake.

What these figures can’t tell us:

Intensity of effect. See the Mercalli Intensity Scale below.

Anything exact. All of that depends on where the epicenter of the quake is, how deep, etc.—considerations that don’t make it into that estimate.

To understand what the above figures mean in less abstract terms, it might be  helpful to take a look at charts that measure these energies according to a scale we can (sort of) understand. Below are two charts, one that measures the Moment magnitudes in terms of nuclear bombs, another that measures them in terms of explosives (TNT).

From the USGS:

According to this chart, the energy released by the 8.8 Chile earthquake correlates roughly to that released by 25,000 nuclear bombs. The Haiti quake released energy equivalent to roughly 25 nuclear bombs.

(Again, take this with a grain of salt—these estimates are for the amount of energy released in total, which in an earthquake would be spread out over a much larger area than, say, a bomb.)

From the University of Nevada, Reno Seismological Lab, a similar chart expressing the energy released in terms of tons of TNT [click to enlarge]:

According to this, the Chilean quake resulted in an energy release approximately equal to 5 billion tons of TNT, and the Haiti quake resulted in a release of 160 million tons of TNT.

A third way to measure earthquakes: the Mercalli Intensity Scale

What the above systems don’t measure are the effects of the earthquake. A scale has been developed for that too. The Mercalli Intensity Scale measures an earthquake’s effects based on descriptions of the experience (in other words, it relies to some extent on subjective accounts, on how the earthquake is narrated):

  • I. People do not feel any Earth movement.
  • II. A few people might notice movement if they are at rest and/or on the upper floors of tall buildings.
  • III. Many people indoors feel movement. Hanging objects swing back and forth. People outdoors might not realize that an earthquake is occurring.
  • IV. Most people indoors feel movement. Hanging objects swing. Dishes, windows, and doors rattle. The earthquake feels like a heavy truck hitting the walls. A few people outdoors may feel movement. Parked cars rock.
  • V. Almost everyone feels movement. Sleeping people are awakened. Doors swing open or close. Dishes are broken. Pictures on the wall move. Small objects move or are turned over. Trees might shake. Liquids might spill out of open containers.
  • VI. Everyone feels movement. People have trouble walking. Objects fall from shelves. Pictures fall off walls. Furniture moves. Plaster in walls might crack. Trees and bushes shake. Damage is slight in poorly built buildings. No structural damage.
  • VII. People have difficulty standing. Drivers feel their cars shaking. Some furniture breaks. Loose bricks fall from buildings. Damage is slight to moderate in well-built buildings; considerable in poorly built buildings.
  • VIII. Drivers have trouble steering. Houses that are not bolted down might shift on their foundations. Tall structures such as towers and chimneys might twist and fall. Well-built buildings suffer slight damage. Poorly built structures suffer severe damage. Tree branches break. Hillsides might crack if the ground is wet. Water levels in wells might change
  • IX. Well-built buildings suffer considerable damage. Houses that are not bolted down move off their foundations. Some underground pipes are broken. The ground cracks. Reservoirs suffer serious damage.
  • X. Most buildings and their foundations are destroyed. Some bridges are destroyed. Dams are seriously damaged. Large landslides occur. Water is thrown on the banks of canals, rivers, lakes. The ground cracks in large areas. Railroad tracks are bent slightly.
  • XI. Most buildings collapse. Some bridges are destroyed. Large cracks appear in the ground. Underground pipelines are destroyed. Railroad tracks are badly bent.
  • XII. Almost everything is destroyed. Objects are thrown into the air. The ground moves in waves or ripples. Large amounts of rock may move.

The Chile earthquake has received a Mercalli Intensity rating of VII. The Haiti quake, in contrast, received Mercalli Intensity rating of IX.

It goes without saying, I hope, that these numbers are the least interesting and least significant aspects of what a comparison between the Chile and Haiti quakes should be. These are (barely) mathematical relationships; even the Mercalli intensity scale captures next to nothing about what it would mean to experience an earthquake in Haiti and one in Chile. They don’t express how Chile and Haiti differ in earthquake preparedness, infrastructure, and wealth; neither do they account for differences in geography and political climate. They are what they are, and to make too much of them would be like evaluating two people based on their respective weights; the information you can usefully extract is awfully limited. Still, these numbers are there, floating in the internetiverse, and since they are, we might as well understand what they do and don’t mean.



Let us descend into the blind world now

I’m not sure whether there’s anything coherent or decent to say about the wreckage in Port-au-Prince. I was in the waiting room of a doctor’s office today, translating a form for an injured patient when footage of the quake aired. I’d read a news headline—7.5, it said—and moved on to the finer points of the Leno-O’Brien catfight without giving the event a second thought. As a longtime resident of the Ring of Fire (on both hemispheres) one thing I’ve learned about earthquakes is that the Richter rating is the least sensational thing about them. If all you hear is a number, chances are a more terrible metric hasn’t yet emerged.

The Haiti footage came on HLN, that catastrophe of a channel that specializes in kidnapped children. This particular doctor’s office has HLN blaring all the time so that the lobby is ablaze with the outrage of Common Sense. It’s hard to blow your nose without feeling like you’ve taken a stand (this is how they talk) on sex offenders. I had Dante’s Inferno with me and struggled in vain to read this bit of Canto IV: “the heavy sleep within my head was smashed by an enormous thunderclap, so that I started up as one whom force awakens.”

The host was a tragic (smart) woman whose job it is to engagingly present people’s Facebook comments on legalizing medical marijuana and whether a mother should or should not have murdered her child. She asks people to please call her or contact her on Facebook to “get your voice heard.” But she is no actress. She is a journalist, despite her good looks and excellent makeup, and her eyes turned almost human when news turned to Haiti and she announced that “hundreds of thousands” were suspected dead.

I put “hundreds of thousands” in quotes because that’s how it appeared onscreen for the rest of the day. A different number was spoken and a new metric has emerged.

I’ve been reading Jincy Willett’s Winner of the National Book Award, which flirts with a tidal wave (a fictional temptation echoed in Margaret Atwood’s short story “Happy Endings” where the fictional author, getting more and more desperate to generate a worthwhile plot, defaults, in version D, to a tsunami). What’s important in Willett’s novel is that neither plotwise nor in fact does the much-feared natural disaster really come.

The next few lines of the Inferno talk about “the melancholy valley containing thundering, unending wailings” in which “though I gazed into its pit, I was unable to discern a thing.”  Being the kind of cold-hearted prig who talks about storytelling when real tragedy hits, I guess I was pleased to gaze into the pit as long as it remained undiscernable. Discernment is vitaminic and cauterizing. Before this 7.5 earthquake happened, I was curious about how this kind of story would be told.

But now?

The temptation, and it’s a real one, is simple and ostrich-like. The temptation is to let this particular set of awful stories go. Better just to help. Isn’t it enough to send money to Oxfam, to the American Red Cross, without having to know anything more? Can’t I be an HLN Facebook commenter? Of what use can it possibly be to find out more about this particular data set?

A tangent, because it’s hard to look some things in the face: fourteenth-century Florence enforced a humanist education as a means of preparing its citizens for what sounds, today, like a freakishly participative government. It was governed by a council of nine men, the signoria, the head of which served exactly two months in office before another one was elected.  (The thought of a presidential election every two months just made me pick at my bottom lip so much it bled.)

The “elections” were lotteries. Theoretically the name of every man over thirty who belonged to a Guild and was free of debt was included. (In practice it was an easy system to game, and the Medicis did, but the model still fascinates me. ) Therefore, it was urgent and important to have an educated public that could rise, if randomly selected, to the challenge of prospective government.

The case for an educated public seems weaker now. (I’m using “educated” broadly here; I’m talking as much about current events as I am about neo-Platonism or calculus.) I want to be convinced of its value.

It’s been suggested that Bush is Exhibit A in the People’s case against American stupidity. Maybe. It may be that an uneducated public elected an uneducated man. I’d suggest, though, that the real driving force behind it all was money, and money has a talent for continually defying our claims for what an education provides.

Because we’re stupid at economics. Economists are as good at money as meteorologists are at weather. Experienced stockbrokers can’t outperform chance.  Education has nothing to do with economics, and our educational system is fundamentally ill-equipped to prepare its citizens to deal with the willful  supranational monster money has become. There are no teachers.

That education has value is basically an article of faith. That’s a weak position for an education to be in, and—to take a premise of Hornby’s fantastic movie An Education seriously—it’s worth considering the merits of intellectual agnosticism.

The usual question—the one An Education asks—is what it means to be participate meaningfully in our own time. What I’d rather ask, in the face of natural disaster, is whether the “meaningful” aspect of our participation as outsiders matters.

My ostrich answer—in which we donate and minimize our exposure to distressing information—offers a great solution, the one I’ve already proposed: money.

The American Red Cross could sell the secular equivalent of papal indulgences.

Hear me out. Back in the day, saints, on their arrival in heaven, would donate whatever extra merit they didn’t need to the Catholic Church. It would be stored in the Great Treasure House of Merit, a nebulous bank of Christian virtue in which  the pope held the only checkbook and wrote people indulgences when they were short on merit of their own, or short on the time required to do penance. (Luther’s first salvo against the pope: that the donated Merit belonged to all Christianity and that the pope was effectively a squatter.)

We could all buy some Haitian relief and it would all have the real merit of real dollars going to real people. Whether we ourselves go through the spiritual steps that precede penance—whether we experience real contrition, or empathy, or anything—seems less than relevant.

Provided we donate, why find out more about Haiti than HLN provides?

I’m groping here*. I’m hoping for something besides the categorical imperative. Journalism depends on our need for news and relies on an ingrained integrity of soul and public-spiritedness that wants its news told accurately and well. Journalism is also (therefore?) dying.

(Another cause we should throw money at?)

A week ago I was interpreting for an injured worker who was undergoing a psychological evaluation. These appointments are the worst. They take forever, they’re grueling for the patient, and they leave my hand cramping from filling in bubbles on a questionnaire that asks you in nine different ways whether you think you have special powers or loved your dead father. Different doctors use different tests. This particular one was 400 questions long.

Before starting, a psychiatrist interviewed the patient, who was, by the way, a sullen, angry-looking man. When the doctor asked him a routine question (“what medicines are you taking?”), the patient burst into violent sobs. Face-time with the doctor was brief; he did what he could, then escorted us out into the waiting room, where another patient and his interpreter were occupying two of four available chairs.

“We don’t have a private room for you,” the psychiatrist said, “but you can do the questionnaire here.”

I stared at him. He was asking my patient to answer 400 questions about his innermost demons IN PUBLIC. With two strangers as inevitable witnesses. (There was no way they could not hear us, just like there was no way for me not to hear HLN over the Inferno.) I told him we needed a private room. He said he was very sorry, there was nothing to be done.

I did my best to construct a sound booth using the questionnaire and to make it seem like it wasn’t him, me, the other patient and the other interpreter. It’s just the two of us! I intimated, as if that were an improvement. I whispered the questions, trying to make it seem like I wasn’t whispering because for either of us to acknowledge that would mean recognizing our position: an outsider sitting next to a stranger whose life is in ruins, asking him over and over whether he still gets erections, whether he cries often, would he steal if no one was watching, does he want to die.


*And I’m less interested in HLN and its many flaws than I am in the whole problem—what, beside Arko Datta’s symbolic photo, we really need.