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Captivating Earthquake Facts

Captivating Earthquake Facts
 

When we look at the most devastating and unpredictable natural disasters that can impact our lives, earthquakes are at the top of the list; to date, the loss of more than a million innocent lives has been recorded.  Powerful earthquakes have caused colossal destruction not only in the areas where they are centered, but neighboring areas as well.  Earthquakes are one of the most dreaded natural disasters because they happen without any warning.  Did you know the following facts?

1.  Nearly 500,000 earthquakes a year occur around the world, as detected by extremely sensitive tracking instruments.  About twenty percent, or 100,000 of those can be felt, and approximately 100 cause damage each year.  In any given year, southern California experiences about 10,000 earthquakes, however most of the seismic activity is not felt by humans.

2.  San Francisco is moving toward Los Angeles at the rate of about 2 inches per year as the two sides of the San Andreas Fault slip past one another.  At that rate, these two cities will come together – in several million years.  Thankfully, this north-south movement also means that despite fears and “predictions”, California will not fall off into the Pacific Ocean.

3.  The Pacific Rim of Fire, a ring of volcanoes around the Pacific Ocean, is the most geologically active region on our planet.  It contains 452 volcanoes and is home to more than 75 percent of the world’s active and dormant volcanoes.  The Ring of Fire touches both the North and South American coasts, as well as countries on the western side of the Pacific (including Japan, Philippines, Tonga, Bougainville, Sumatra, Bali, Java, Flores, Timor, and New Zealand).  Because the Pacific Ring of Fire is an area where multiple major plate boundaries collide, it is also the area where most of the Earth’s major quakes occur.

4.  Oil extraction can cause minor earthquakes.  Because oil generally is found in soft sediment, when the oil is removed other rock moves in to fill the empty space; this creates “mini-seismic events” that are not noticeable to humans.

5.  There’s no such thing as “earthquake weather.”  According to the U.S. Geological Survey, statistically, there is an equal distribution of earthquakes in cold weather, hot weather, rainy weather, and so on.   Scientists agree that there is no physical way that weather could impact forces that occur several miles beneath the surface of the earth where quakes originate. The changes in barometric pressure in the atmosphere are minimal compared to the forces in the Earth’s crust; the effect of the barometric pressure does not reach beneath the soil.

6.  March is not an earthquake monthdespite what some folks believe.  Statistics show that there are only a few earthquakes recorded in the month of March.  It is a fact, however, that one of the largest earthquake (magnitude 9.2) ever recorded happened on March 28, 1964, in Prince William Sound, Alaska.  This particular earthquake killed 125 people and caused $311 million in property damages.  Reviewing additional earthquake history, one will find that the next three major earthquakes in the United States occurred in February, November and December.  The month of February is considered to be the month of earthquakes and is often celebrated as earthquake awareness month.

7.  Quakes on one side of the Earth have been known to shake the other side of the planet.  When seismologists studied the devastating 2004 earthquake that triggered devastating tsunamis throughout the Indian Ocean, they found that the mighty quake had weakened part of California’s famous San Andreas Fault.  The powerful Chilean temblor of 1960 shook the entire Earth for many days, a phenomenon called oscillation that was measured by seismic equipment located around the world.

8.  A city in Chile moved 10 feet in the massive 8.8 magnitude earthquake that occurred on February 27, 2010.  Incredibly, the split in the earth’s crust shifted the city of Concepción to the west. Scientists believe that this particular temblor changed the planet’s rotation slightly and shortened the length of Earth’s day by 1.26 microseconds.

9.  Earth’s bulge was trimmed slightly by the 2004 Indonesian earthquake, a 9+ temblor that created a deadly tsunami.  Earth’s midsection bulges in relation to the measurement from pole-to-pole; the catastrophic land displacement caused a small reduction in the bulge, making the planet more round.

10.  The largest earthquake ever recorded was a magnitude 9.5 in Chile on May 22, 1960.  The deadliest earthquake ever struck Shansi, China, on January 23, 1556. Some 830,000 people are estimated to have died.

Over the last 30 years, as understanding of earthquakes has increased and technology has improved, California has come up with better ways of making structures sound enough to withstand a quake.  City and state building codes have been revised and they now require specific tests for any masonry that is used to construct new buildings.  Brick walls must meet specifications for facing, bonding and distance between headers.  Masonry must be tested using an in-place shear test that displaces a single brick, then applies weight and checks for movement.  Wall anchors are tested and must pass code requirements, and embedded wall bolts are periodically inspected.

Recent earthquakes in California have provided evidence of how efficient the new building codes are when it comes to construction and retrofitting. There are still many older buildings located throughout California, including commercial properties in the Los Angeles area, which have not yet been retrofitted.  If you are a commercial property owner and would like to find out more about whether your property should be strengthened and reinforced to withstand the impact of an earthquake, call Saunders Seismic Commercial Retrofit today!

Southern California Office

(949) 646-0034

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