There are many different natural disasters that can have an overwhelming impact on our lives. Incredibly forceful seismic activity is at the top of the charts. Not only do powerful earthquakes destroy buildings and businesses, many innocent people are injured or killed as the earth moves and shakes. Because mighty quakes happen without warning and can cause additional types of destructive forces, they are considered to be the most dreaded of all natural disasters.
As we have seen recently, massively destructive earthquakes can happen anywhere around the globe. Within the last two months, we have seen pictures coming out of Nepal, showing unimaginable devastation and loss of life after a 7.8 temblor hit the capital of Kathmandu. Most people who live along our West Coast have heard the predictions that a mighty temblor is expected to happen at some point within the next twenty to thirty years. There are many fault lines located throughout the state of California and many cities and towns, including those in the Bay area, experience frequent tremors. No one ever really gets used to seismic activity; each time the earth starts to rock and roll, area residents, along with business and commercial property owners, wonder if it is the start of the BIG ONE.
Scientists and historians are always researching and documenting information about natural disasters that have happened around the world. For those who have not thought much about earthquakes, here are some intriguing earthquake points to ponder:
- Typically, it’s not the force of the earth itself moving that injures or kills people during a powerful earthquake; it’s the related damage caused by the destruction of surrounding infrastructure and man-made properties that are not strong enough to withstand powerful quakes. Approximately 8,000 people are killed each year as a result of an earthquake, and, in fact, it has been estimated that 13 million people have died over the past 4,000 years as a result of seismic activity. In addition, other natural disasters often occur as a result of a major temblor, including tsunamis, avalanches, mudslides and floods. These earthquake-related natural disasters add to the devastating impact that results when the Earth’s crust releases stress.
- It wasn’t until the mid-twentieth century that the theory of plate tectonics was developed. Scientists have determined that there are twenty different tectonic plates, which are giant slabs of rock that make up the upper layer of the Earth’s crust. Over time, these plates shift and move, regularly sliding along each other and sometimes colliding. Incredible stress builds up between the plates as they are moving and shifting; the stress increases until the crust can no longer handle it and it breaks apart to release the stress. As the stress is released, it sends seismic waves (vibrations) potentially hundreds of miles up to the Earth’s surface. We call these seismic waves earthquakes or temblors.
- These seismic waves are sometimes called shock waves and there are two distinct types. Side-to-side waves are called Love waves. Shock waves that roll through the Earth’s surface are called Rayleigh waves; these shock waves have been known to travel upward so far that they can cause disturbances 50-300 miles above the Earth’s surface in the ionosphere. The fastest seismic waves have been recorded at 225 miles per hour.
- Most of us remember the undersea earthquake in the Indian Ocean that triggered a chain of devastating tsunamis on Dec. 26, 2004. When an earthquake happens under the ocean, it can trigger a tsunami that moves away in all directions. A tsunami travels incredibly fast at up to 600 mph and when it reaches shore, it will quickly rise up to heights of more than 100 feet. As the massive wave hits the shore, it submerges and destroys everything in its path.
- Smaller, less powerful seismic activity, called aftershocks, often occur after a major earthquake. These aftershocks happen as the faults and plates adjust to stress-relieving initial quake, and they can happen for several years later. Aftershocks that happen soon after the earthquake often make rescue efforts much more difficult and they can cause additional injury, deaths and building damage.
- Close to 80% of all the Earth’s strongest seismic activity happens along the “horseshoe” rim of the Pacific Ocean, where a number of tectonic plates come together. This extensive area, which is often called the “Ring of Fire”, is also the home of more than 75% of the world’s volcanoes, both active and dormant. Pakistan, India and Turkey are part of an area known as the Alpide Belt, which is a region considered to be the second-most earthquake-prone area. Approximately 17% of the world’s largest earthquakes, including the recent temblor in Nepal, occur in this area that extends from Java, through the Himalayas, into the Mediterranean Sea and out to the Atlantic.
- Based on recorded history, in 1070, an earthquake in Peru caused a horrific avalanche that destroyed and carried away multiple villages, killing 18,000+ people. A massive wave of ice and rock moved down the mountain at approximately 250 miles per hour, demolishing everything in its path. In 1920, China experienced an incredible landslide that killed almost 200,000 people. The landslide was caused by a powerful earthquake in the region.
- Japan, on the western side of the “Ring of Fire”, is known as one of the Earth’s most earthquake-prone countries. An earthquake that occurred in Kobe in 1995, lasted no more than 20 seconds; in that short amount of time, more than 100,000 buildings were completely destroyed, leaving 300,000 residents without homes. As horrendous as the 1995 earthquake was, it was definitely not the worst earthquake in the history of Japan. Four years ago, a 9.0 temblor off the main island of Japan, along with the subsequent tsunami, wiped out towns along the coast and severely damaged several nuclear power plant facilities. After the 1995 earthquake, Japan placed special sensors throughout the country. Thanks to those high-tech sensors, seismologists were able to capture much more data than in prior quakes, making the 2011 historic temblor the best-recorded in history.
- The San Andreas Fault zone, where the Pacific and North American plates meet, is the longest fault zone in the world. Covering more than 800 miles from northern California to Mexico, it is actually a system of many fractures and faults that mark the area were the tectonic plates are sliding along past each other. In some places along this fault zones, there are a series of faults located close together. Over time, new faults and fractures have been found in the San Andreas Fault zone. Within the last 10 years, three new faults have been discovered in Mendocino County, located in northern California.
While these are certainly intriguing points to ponder, scientists still do not have a way to accurately predict powerful seismic activity. Residents and commercial property owners in California, including the Bay Area, need to be mindful that a powerful quake could happen at any time. Is your property strong enough to withstand the powerful forces of nature? If you are a commercial property owner in the Bay Area, and your property was built more than 30 years ago, it is time to consider an earthquake retrofit to ensure your building is strong enough to withstand the next history-making temblor. Have a professional and experienced earthquake retrofit contractor inspect your property to determine any safety issues and retrofitting maintenance concerns – before the BIG ONE happens. To schedule an earthquake retrofit inspection, call Saunders Seismic Commercial Retrofit today!