Earthquakes! Are They Happening More Often And Getting Bigger?

Are More And More Earthquakes Happening?

Are more earthquakes happening and are they getting bigger?

 

There seem to be more and more earthquakes around the world and they seem to be getting bigger and bigger, but is it just that more are now getting reported?

 

Scientists Say There Was No Increase In The Really Big Earthquakes

Earthquakes of magnitude 7.0 or greater have remained fairly constant.

According to long-term records (since about 1900), we can expect about 17 major earthquakes (7.0 – 7.9) and one great earthquake (8.0 or above) in any given year.

Why Does It Seem Like There Are More Earthquakes?

Video Courtesy Of National Geographic

It’s because of the tremendous increase in the number of seismograph stations in the world and the many improvements in global communications.

In 1931, there were about 350 stations operating in the world, but today, there are more than 8,000 stations, and the data now comes in rapidly from these stations by electronic mail, the internet and via satellite.

This increase in the number of stations, and the more timely receipt of data means that many small earthquakes which were undetected in earlier years are now being recognized.

The NEIC (National Earthquake Information Center) now locates around 20,000 earthquakes each year or approximately fifty every day.

Also, because of the improvements in communications and the increased interest in the environment and natural disasters, the public now learns about more earthquakes.

So Why Are More And More People Killed By Earthquakes?

Population booms are contributing the the perception that there are more earthquakes.

And many of these population increases are in earthquake-prone areas, so there is a higher possibility of more casualties when a major quake strikes.

"We have not seen any statistical increase in the number of earthquakes if you look back over the tens and hundreds of years".

"However, unfortunately the recent earthquakes have impacted populated areas, which brings them into the news, and people become more aware of the earthquakes".

"In 1960, Haiti had a population of 3.87 million, according to the World Bank data finder. Since then, it has more than doubled to 9.84 million as of 2008".

said Paul Earle, a USGS seismologist.

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7 Responses to Earthquakes! Are They Happening More Often And Getting Bigger?

  1. knopfman says:

    According to the USGS (U.S. Geological Survey) the number of large earthquakes has stayed relatively constant, large meaning magnitude 6.0 and greater and the linked article carries a lot of additional earthquake relate data.

    The Richter Scale was invented by Californian Geologist Charles Richter and the following should provide a non-technical insight as to it’s ratings.

    Less than 3.5
    Generally not felt
    3.5-5.4
    Often felt, but rarely causes damage.
    Under 6.0
    At most, slight damage to well-designed buildings, but can cause major damage to poorly constructed buildings over small regions.
    6.1-6.9
    Can be destructive in areas up to about 100 kilometers across where people live.
    7.0-7.9
    Major earthquake. Can cause serious damage over larger areas.
    8+
    Great earthquake. Can cause serious damage in areas several hundred kilometers across.

    Some more detail for those that want it ;-)

    A magnitude zero earthquake is rated as one in which the earth’s surface quakes/moves one micro-metre at a distance of 100 kilometers from the epicenter of the earthquake.

    * One meter = 1 million micro-meters.

    * Epicenter = "ground zero" for earthquakes.

    A quake of magnitude 1 is ten times and therefore causes the ground to move about 0.01mm at 100km from the center. A magnitude 2 earthquake would cause movement of 0.1mm, and a magnitude 3 would cause movement of one millimeter at that distance.

    By the time you get to magnitude 4 earthquakes, they are definitely starting to be noticed, because 10mm (1centimetre) of movement is noticeable.

    A magnitude 5 earthquake causes 10 centimeters of ground shake at 100km away, and that is usually enough to be on the news.

    Magnitude 6, with its associated one meter of quaking (at 100km distant) is likely to cause buildings to collapse.

    In a magnitude 7 earthquake, it’s best not to be within 100km of it, and seismographs of the type used for calibrating the Richter scale don’t work above magnitude 6.3 , so some estimation has to be done.

    With the larger magnitude earthquakes the survival rate for people and seismometers near the event is poor, so estimates then have to be based on how much displacement is measured a few thousand miles away, or how big a tsunami was if one was caused.

  2. live-one says:

    Thank you Knopfman for the info which is really informative and clear and truly on a par with all your excellent posts.

    I did just want to add that whereas the Richter scale measure the magnitude of earthquakes by the order of magnitude of the amount of earth-movement caused at a distance from the epicenter of the event, that is quite different from the amount of energy that they release.

    So if you wanted to compare earthquakes with nuclear explosions measured in megatons, then you need to consider that energy doesn’t translate directly into distance, because it spreads out.
    What this means in a practical sense, it takes 1000 times as much energy to cause 100 times as much movement.

    Or to put it another way, for each extra Richter magnitude number multiply the distance moved by 10 and the energy by 32, therefore a one megaton bomb is approximately equivalent to a magnitude 7 on the Richter Scale.

    A magnitude 4 earthquake is therefore equivalent to 1 kiloton of bomb explosion, and a magnitude 7 is equivalent to 1 megaton.

    But be careful when doing calculations based on this however because a 10 megaton bomb would be equivalent to magnitude 8 and only if the bomb was exploded underground.

  3. knopfman says:

    And thank you live-on!

    I am truly flattered, and how much money did you actually want to borrow? ;-)

  4. no-shmuck says:

    Well Japan’s 8.9 quake and the following tsunami should worry people in California and some other places too!

    The earthquake that struck off the northeastern shore ranked as the fifth-largest earthquake in the world since 1900 and was nearly 8,000 times stronger than one that devastated Christchurch, New Zealand, last month.

    Since the quake, more than 1 million households have not had water, and more than 215,000 people are living in 1,350 temporary shelters in five prefectures, or states.

    Things seem to be out of control at the Fukushima Dai-ichi nuclear plant and workers are unable to approach the plant, and 140,000 people have been ordered to seal themselves indoors after a series of explosions and fires.

    The latest fire, at the plant’s No. 4 reactor, is said to be under control, but Japan’s nuclear agency was unable to confirm that the blaze had been put out, and clouds of white smoke are billowing from the reactor.

  5. tiffany34 says:

    I can’t believe how bad it has gotten in Japan. Anyone who lives near a fault line should pick up some emergency supplies for the future. There are lots of sites like http://www.buyearthquakekit.com where you can pick up some basic supplies that might save your life. Thoughts and prayers to those in Japan.

  6. Tiffany says:

    I also believe that earthquakes now are getting frequent and getting bigger. I believe this has something to do with the climate change we’re having.