Natural Disasters

Has the frequency of natural disasters increased over the past couple of years or is this only my perception? Until a couple of years ago it seemed rare to hear about an earth quake or some other natural disaster. Now it seems (to me) like they happen at least every couple of months.

If the rate has in fact increased is there some geological (not sure that it the correct term) explanation for the increase?

Thanks.

This site - http://www.earth.webecs.co.uk/ - appears to show that the frequency of earthquakes of 7.0 and up have increased since the 1970’s, and this one - http://www.sciencedaily.com/releases/2007/07/070730092544.htm - says the frequency of Atlantic hurricanes has doubled in the last 100 years, so there would appear to be at least some evidence to support your perception.

Grim

Well maybe, I’m not thrilled buy this piece of your link About the “End Times”

Nor am I thrilled by the deceptive earthquake frequency/year graph that fails to actual put labels on the x or y axis and relies on someone to read the article and note that the counts include lower magnitude quakes that would only now be noted.

If you looks at the USGS http://earthquake.usgs.gov/earthquakes/eqarchives/year/graphs.php and looks at Magnitude 7 quakes the yearly occurrence is pretty close to the mean value of 12. The Magnitude 8 + 9 has a spike but the occurrences per year is so small that 4 quakes is a doubling.

I wonder if anyone does a global energy release metric. I can see stresses adding up and once 1 piece slips the other pieces relax as well leading to more quakes over a period of time.

I’ll grant that that graph is pretty dramatic, but I wonder what 1900-1973 would have looked like. It’s possible that we’re just in the middle of a typical 50-year cycle.

Ohhh - look what I found http://earthquake.usgs.gov/research/data/centennial.ph

If you group earthquakes by magnitude group (6, 7, etc) I don’t see a change in 7s through time.

Also I’d suspect the source of that graph since it only references back to some web page expecting the UN to rescue LA from “external threats” or some such nonsense.

Do you know if aftershocks would be included in these figures as long as the strength of the aftershock was severe enough to meet thier criteria? In other words, would the 7.0 aftershock that hit Japan today be included in these numbers or would it not since it is considered an aftershock?

Sorry if these are dumb questions, but I obviously know nothing about this subject and have only recently become interested in it.

Thanks.

I don’t see why not.

What clearly has changed to a much greater degree than anything else is the ubiquity of instant reporting/video from around the world and the media realization that weather and other natural disasters sell well and don’t cost much at all to produce coverage of.

…and magnitudes aside, since there are more people all the time, it stands to reason that natural disasters will more frequently happen where there are more people, which makes any disaster at least more dangerous, and probably more deadly.

detection methods have also improved. otherwise, earthquakes and volcanic eruptions occur everyday.

We have done this same thread several times recently. Like immediately after each recent highly publicized natural disaster. My searching didn’t find those threads; perhaps somebody else will have more luck.

No, nothing is different but the fact you’re now paying attention.
As to big earthquakes which are quite rare, it’d take several years, maybe decades of actual change before the historical data would show cleary & unmistakably that something has changed. Obviously if 8.5s started happening every 30 minutes and did that continuously for a couple weeks, all but the most clueless skeptic would conclude that something really was happening. But for realistic geophysically plausible rates of increase, it’d be a long time before we could conclude for sure. Just look at the flail about global temperatures. Is it or isn’t it?

What is different, I think, is the number of people that have died: close to a quarter of a million each in Haiti and the Indian Ocean Tsunami, and then the 20,000 in Japan–a smaller number, yes, but we tend to think of industrialized nations as immune to that sort of loss of life, so it is memorable. Hell, even the 1800 or so Katrina-related deaths was shocking, as well–the last time a natural disaster in the U.S. had a death toll like that was the 1920s, before the vast majority of people in the U.S. were born.

I am not in any way, shape, or form suggesting this is any sort of meaningful pattern: it’s just a run of bad luck. That said, it’s not just confirmation bias that makes things seem different: it’s the loss of life. Natural disasters may be chugging along at the same rate as ever, but there really has been an uptick in tragedy.

What’s interesting about recent high death tolls is that we’re seeing the consequences of creating very densely-populated areas out of disaster-prone regions. The more people that you have living very near the coast, the greater the risk is of a high death toll from an event such as a tsunami or hurricane. Now, if this event is well forecast (as most hurricanes and long-distance tsunamis are), the loss of life can usually be kept down. When there’s little warning, such as with the Japan and Indonesian tsunamis, the risk to life increases dramatically.

There are societal issues as well. There’s an old adage that “earthquakes don’t kill people, buildings kill people.” And this is true when you look at events like the Haiti earthquake and see what even a moderate quake can do to substandard housing: the result is enormous death tolls in a relatively small area. In Katrina, many people either refused to evacuate or did not have the means to do so; unfortunately, they were positioned in some of the worst possible places to be when a storm of that intensity struck (parts of New Orleans being below sea level and the Mississippi Gulf Coast being one of the most storm surge-prone areas of the country).

It’s hard to say if the disasters themselves have increased in frequency. This cannot be meaningfully estimated by looking solely at written historical records, because the fact is that today we pay more attention to all disasters more than we ever have, and reporting networks are far superior than in the past.

Tornadoes were not meaningfully counted in the United States until public tornado forecasting began in the mid-1950s, and the vast majority of tornadoes went unreported before then.

Until the advent of weather satellites in the 1960s, many hurricanes likely went unnoticed, especially those that stayed far out at sea.

And seismic networks have given us huge insights as to how many earthquakes we actually have: there isn’t a spot in the world now where a major earthquake could go unnoticed. Contrast this with the era before seismograph networks were set up: probably the most intense earthquake ever to hit the continental U.S., the 1700 Cascadia Megathrust Quake, was only positively identified first by Japanese reports of a major tsunami without an accompanying earthquake, and then by modern-day dendrochronology on the Pacific Northwest coast. No way that a quake that large would go unnoticed today.

Yes, but I don’t see that those things have changed meaningfully in the last decade. The same eartthquakes in the same spots would have had the same death tolls ten or fifteen years ago.

I don’t think so. The underlying cause of earthquakes is plate tectonics. A particular plate boundary may become more or less prone to generate earthquakes over time, but I don’t think there is any global mechanism that could increase the number of quakes.

The Earth’s core is very slowly cooling, so over very long periods of time (hundred of millions of years) I’d expect the number of quakes to decrease.

Statistically, it would be strange if the number of major quakes was the same each year. Clumps in data-sets are natural, because there are more possible combinations with clumps than there are those with a stready rate of events. For example, if there are 12 major quakes a year on average, there is only one data set that goes 12-12-12-12. There are far more that go something like 9-10-15-14. The trend in the later set towards more quakes may not be statistically significant.

I didn’t say that they had changed meaningfully over the past decade. Changes like people concentrating in coastal or other vulnerable areas takes place over longer periods of time than that.

What I guess I should have said before (it was early in the morning and I wasn’t as clear as I should have been) is that disasters like the Japan quake, the Haiti quake, Katrina, etc. are recent examples of “worst case scenario” disasters - meteorologists had been hypothesizing a Katrina-like disaster in New Orleans for years before Katrina hit, for example, and Japan had never experienced a magnitude 9.0 quake in recorded history, much less one close enough to the coast to trigger a tsunami with less than an hour lead-time for evacuations.

The Münchner Rück (Munich Re), which is an insurance company that insures other insurance companies (hence the Rück, or Re)* has figures for the last 30+ years, and definitly can see that natural disasters have increased, in two ways:

The strength and frequency of natural disasters except Earthquakes have greatly increased in the past decades, e.g. more hurricanes, and more hurricanes of level 4 and 5 where before they were level 3 and 4

The amount of damage done has increased, because people have more expensive homes and toys that are insured; and because people have built increasingly in places they shouldn’t - close to rivers that flood, close to mountains that send avalanches etc.

This increased building and living in danger zones also means that more people suffer when a disaster strikes. This (more property damage, more people affected) leads to more media coverage.

The Munich Rück is in no doubt at all that the climate change is directly linked to increased flooding, increased hurricanes and all other natural disasters except earthquakes. Earthquakes have their seperate rhythm, related to the Earth’s magma cycle, which means that if the time is “right” for it, there will be a cluster of earthquakes and volcano eruptions because of built-up pressure and movement all around.

That’s why a big (millions of Euros) company spends a big amount of money researching climate change, hoping to avert it, because it’s good business sense to think ahead.

  • that is, company ABC insurance has a contract with you Joe Smith for your house in case of natural disaster; and ABC insurance has another contract with Munich Re in case something happens to them.

An increase doesn’t mean it will continue to be an upward trend. Some things could be just cyclical, no?

Or…there will be an 11.0 earthquake that rips the Earth in half and the world starts anew. shrug We’ll be the dinosaurs for scientists millions of years from now.

AGW is not cyclical, it’s rising out of control, and scientists are predicting the effects on weather phenomena, from which damages can be calculated.

As for earthquakes, I did say they are cyclical! Although even there, population increase have worsened the situation. In addition, even there, climate change affects things on top of other phenomenen: earthquakes causing tsunamis is one thing, but with rising temp.s, the ocean expands, meaning more water, meaning more flood waves after an earthquake.

Or: the glaciers in Greenland/Iceland melt off, and the weight of thousand meter ice being removed makes the upper Earth crust go “sproing” upwards a bit, which is not good for the surrounding areas.

Don’t be silly, nobody said that. Earthquakes are tiny for Earth as a whole. Nobody says that humans can destroy Earth; we can and have fucked up the living conditions for us, however.

And the dinosaurs existed for 100 million years all in all, humans are far short of that. We will be blips on the global scale for future scientists, with the most interesting feature “How could they be so stupid?”.