World Earth Quake History 1 A.D. to 2010

It does seem like we are having a lot more Earth quakes and tsunamis right now, but we shouldn't be jumping to conclusions yet. Phage made some valid points and we also didn't have such an extensive news media in our past. We might be experiencing frequent activity right now, but this doesn't mean it is going to progress and destroy the world.

reply to post by dusty1

So the USGS no longer shows all worldwide earthquakes. only certain earthquakes?

Apparently so.

The USGS estimates that several million earthquakes occur in the world each year. Many go undetected because they hit remote areas or have very small magnitudes. The NEIC now locates about 50 earthquakes each day, or about 20,000 a year.

earthquake.usgs.gov...


They omit earthquakes outside the US that were less than magnitude 4.5 and so slight they weren't even reported as felt (they do include those that were). So what? These are tiny earthquakes, there are probably many that are not even detected much less felt. Check the chart they show, in 2000 there were more than 12,000 earthquakes worldwide less than magnitude 4.

Because they recently don't record those thousands of unfelt earthquakes (outside the US) does that indicate that there are more earthquakes recently than there were in the past? I don't see how. It's the same problem, sort of, you're saying a lack of data shows something. This doesn't help your case.

[edit on 2/28/2010 by Phage]

reply to post by Phage


So let me recap.

I find an earthquake time line on Google from 1 AD to 2010 which appears to show an increase in earthquake activity.

You show me a graph from the USGS dating back to the year 1900. It shows only 7+ magnitude earthquakes. You then say that there is no telling where the Google graph comes from and dismiss it.

I then show you a graph from theNG DC historical references of 7.5+ magnitude earthquakes dating back to 2150 BC that may show an increase in earthquake activity.

Then you dismiss the NGDC historical graph because it is filtered and shows only earthquakes 7.5+ magnitude and higher. You would have me believe that I can only trust the USGS graph showing 7+ magnitude earthquakes (filtered) and higher from 1900 to 2005.

The OP covers a span of 2000 years. Your graph covers 110 years.

But what you continue to dodge, is that the increase in data collection since 1900 could have coincided with an uptick in earthquake activity.

You have some logical arguments, but beware the absolute.









[edit on 28-2-2010 by dusty1]

reply to post by dusty1

You have it mostly right, except for the "significant earthquake" filter. It does not only include earthquakes of 7.5 and higher. There are many which are less severe.

What absolute? I've only pointed out that the long term data is insufficient and that more recent data does not support the claim.

reply to post by dusty1


Once again, there is no way to accurately compare earthquakes from the first century to the 21st century. The world is much more populated, technology is better, documentation of earthquakes is standardized to a set scale, and we don't have to worry about the Middle Ages destroying our records. No matter what you want to believe, there is no possible way that you can compare the frequency of earthquakes of the past with the measurements of today.

reply to post by Phage

The Significant Earthquake Database contains information on destructive earthquakes from 2150 B.C. to the present that meet at least one of the following criteria: Moderate damage (approximately $1 million or more), 10 or more deaths, Magnitude 7.5 or greater, Modified Mercalli Intensity X or greater, or the earthquake generated a tsunami.

Perhaps I am misreading the above.

What absolute? I've only pointed out that the long term data is insufficient and that more recent data does not support the claim.

You are looking at the recent (and measurable) data and drawing a conclusion. Fair enough.

You aren't Vulcan by chance, are you?

reply to post by dusty1

Yes, you are misreading.

The Significant Earthquake Database contains information on destructive earthquakes from 2150 B.C. to the present that meet at least one of the following criteria

If you check, there are many less than 7.5. Much less.


[edit on 2/28/2010 by Phage]

reply to post by Phage


Why would the USGS in your graph only show 7+ magnitude earthquakes? Doesn't that distort the data from 1900 to present, when compared to the NGDC graph?

I was also wondering where you found that graph on the USGS website?

[edit on 28-2-2010 by dusty1]

reply to post by dusty1

It makes sense to use earthquakes of magnitude 7.0+ because for most of the last century there were few seismographs in the world. This means that weaker earthquakes in remote areas would not be detected at all (there's that lack of data thing again). Earthquakes of 7.0 and greater can be detected pretty much worldwide so by using that as a cutoff point it allows a clearer baseline. Since that data is known to be incomplete it cannot be considered. In the same way, the data from 1000 years ago is incomplete in the extreme and is not of any statistical value.

The "significant earthquake" graph is highly distorted because it uses various unrelated criteria for its filter. The data is of interest historically but it too is not useful for statistical purposes.

I made the graph. The data source is provided.

reply to post by Phage

I made the graph. The data source is provided.

Cool home made graph! Thank you for your efforts.

That is the problem with the USGS website. They seem reluctant to show earthquake history in a visual format.

So do you think the NGDC data from as early as 1945 to present, is inaccurate?

[edit on 1-3-2010 by dusty1]

reply to post by dusty1

Even in 1945 there were not enough seismographs and communications were inadequate to locate mild earthquakes worldwide.

In 1931, there were about 350 stations operating in the world; today, there are more that 4,000 stations and the data now comes in rapidly from these stations by telex, computer and satellite. This increase in the number of stations and the more timely receipt of data has allowed us and other seismological centers to locate many small earthquakes which were undetected in earlier years, and we are able to locate earthquakes more rapidly.

earthquake.usgs.gov...


The data is valid. It's source is the same database, it just filters it oddly which makes it useless for counting earthquakes. If you just use the earthquakes of 7.5 and greater there is nothing wrong with it. It's when you start adding the other criteria that you run into problems.

For example, there are 349 earthquakes of less than 7.5 (72 less than 6.0) included because they produced a tsunami. Of course, lesser earthquakes which occurred away from water may not be included because they could not have produced a tsunami.

reply to post by dusty1
Yeah I would say that is true,.. I was looking for all the info and it is not all there. Ex: for Yellowstone, it shows some data of a years worth at 1. to 1.5 but it is not all there. I may be missing something simple here but it seems incomplete. Sorry to jump in here guys, your debate is great.



[edit on 1-3-2010 by Lil Drummerboy]

reply to post by Phage


So the raw data does show an increase in measured earthquake activity since 1900, but we must edit the data. We are to only take into account 7+ magnitude earthquakes since 1900.

A: Although it may seem that we are having more earthquakes, earthquakes of magnitude 7.0 or greater have remained fairly constant throughout this century and, according to our records, have actually seemed to decrease in recent years

USGS

So the USGS says that while earthquakes "seem" to be increasing, their records "seemed" to indicate a decrease of 7+ magnitude earthquakes. But they leave out data for smaller earthquakes.

The data is the data. Why must it be qualified? Lets say I am trying to prove a point. I open a large book showing all kinds of data. I then but both hands and a foot to cover some of what I believe to be irrelevant data (and it may very well be irrelevant). I tell you that you should only view the data between here....and....here. What would you think?

We are told prior to 1900 the historical data is incomplete.

We are told data from 1900 to ? isn't accurate. Not enough seismograph stations.

We are told any perceived increase in earthquake activity must be due to the increasing number of seismograph stations.

Therefore, we can only trust fairly recent readings.


Can this same methodology be applied to Climate Change as well?
Does the USGS apply these same standards to Global Warming?

reply to post by dusty1

The, "seem that we are having more earthquakes" is in response to the question, "Why are we having so many earthquakes? Has earthquake activity been increasing?" It "seems" to some people that we are having more earthquakes but the data does not indicate that.

I explained why the data is "qualified". Data is not disregarded because it is irrelevant, it is because it is incomplete. We could use more recent data with a higher level of confidence when looking at the short term but that doesn't help when looking at the longer term. You have to compare apples with apples. We can trust the older data on larger quakes because we have been able to detect them worldwide for a longer period of time.

Determining global temperatures is a much more complex problem than simply counting earthquakes. The two cannot be compared.

reply to post by Phage

It "seems" to some people that we are having more earthquakes but the data does not indicate that.

according to our records, have actually seemed to decrease in recent years.

Myths


The "unqualified" data indicates an increase. But it must be "qualified" for reasons you pointed out in earlier posts.

But what you really mean is the "qualified" data doesn't "seem" to indicate an increase but a decrease.


I guess if I feel an earthquake, it doesn't count, if it isn't over 7+ magnitude.

reply to post by dusty1


Can you feel a mild earthquake that happens on the other side of the world?

I've tried three times to get the point across and can't do it.

reply to post by Phage

Determining global temperatures is a much more complex problem than simply counting earthquakes. The two cannot be compared.

Wow this earthquake thing doesn't seem simple at all. We can't just count earthquakes we need delicate instruments positioned in thousands of locations all over the globe to get any kind of handle on qualified data.

So the data on Climate Change must really be a slippery pig. I can feel a tremor, but 1/2 a degree difference on the ol' thermometer is really tough to read.

reply to post by Phage

Can you feel a mild earthquake that happens on the other side of the world?

I've tried three times to get the point across and can't do it.

I see your perspective now. An earthquake is simply data from the other side of the earth.

I understand your point completely, and you are probably correct.

Sorry dusty, I'm afraid I don't think either graphs in your posts have complete records. Others already said that we don't have ways of measuring in the past, population spread isn't as great as it is now, we have better equipment, etc.

We also had many wars all over the world where books and historical records were burned, so it's safe to assume that at least some records were lost.

To add to the discussion, this summary of a paper indicates that there were 181 historical earthquakes from 1365 B.C. to 1900 A.D in Syria alone. I quickly scanned the larger frequency years during these years in the graph from your first post; it's obvious these known earthquakes were not included in the graph. Therefore this paper proves that the graph is incomplete.

I'm pretty sure if I were to study the historical stories and accounts from all civilizations around the world from earlier years, more earthquakes would be shown to be missed in these charts.

reply to post by ATSdelurker


Thank you for that link. I found it interesting.