Earthquake Explained

June 11, 2023 – A 5.0 magnitude earthquake shook South Africa’s Johannesburg on Sunday morning.

The U.S Geological Survey  said the earthquake occurred at 0038 GMT at a depth of 10 km.

Some Johannesburg residents reported feeling tremors.

A resident on twitter said and i quote, “Earth tremor in Johannesburg. Longest and strongest I have felt! Went on for about 30 seconds, it felt like,” one resident wrote on Twitter.

Security risk and crisis management consultancy Crisis24 said there were no reports of damage or casualties as a result of the earthquake.

Today on space.com, we will be looking at earthquakes, countries most hit by earthquake and possible early detection…..

What Is An Earthquake?

An earthquake is an intense shaking of Earth’s surface. The shaking is caused by movements in Earth’s outermost layer.

Earliest Earthquake

The earliest earthquake for which we have descriptive information occurred in China in 1177 B.C.

The Chinese earthquake catalog describes several dozen large earthquakes in China during the next few thousand years.

Earthquakes In Europe Are Mentioned As Early As 580 B.C., but the earliest for which we have some descriptive information occurred in the mid-16th century.

The earliest known earthquakes in the Americas were in Mexico in the late 14th century and in Peru in 1471, but descriptions of the effects were not well documented.

By the 17th century, descriptions of the effects of earthquakes were being published around the world – although these accounts were often exaggerated or distorted.

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1964 Quake: The Great Alaska Earthquake

“1964 Quake: The Great Alaska Earthquake”  is an eleven minute video highlighting the impacts and effects of America’s largest recorded earthquake. 

It is an expanded version of the four minute video “Magnitude 9.2”.  Both were created as part of USGS activities acknowledging the fifty year anniversary of the quake on March 27, 2014.  

The video features USGS geologist George Plafker, who, in the 1960’s, correctly interpreted the quake as a subduction zone event. 

 This was a great leap forward in resolving key mechanisms of the developing theory of plate tectonics.  

Landslide impacts and the extreme tsunami threat posed by these quakes are also discussed. 

Loss of life and destruction from the earthquake and accompanying tsunamis was the impetus for things like the NOAA Tsunami Warning Centers and the USGS Earthquake Hazards Program.

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Why Do Earthquakes Happen?

Although the Earth looks like a pretty solid place from the surface, it’s actually extremely active just below the surface.

The Earth Is Made Of Four Basic Layers: A Solid Crust, A Hot, Nearly Solid Mantle, A Liquid Outer Core And A Solid.

The solid crust and top, stiff layer of the mantle make up a region called the lithosphere. The lithosphere isn’t a continuous piece that wraps around the whole Earth like an eggshell.

It’s actually made up of giant puzzle pieces called tectonic plates. Tectonic plates are constantly shifting as they drift around on the viscous, or slowly flowing, mantle layer below.

This non-stop movement causes stress on Earth’s crust. When the stresses get too large, it leads to cracks called faults. When tectonic plates move, it also causes movements at the faults. An earthquake is the sudden movement of Earth’s crust at a fault line.

The Location Where An Earthquake Begins Is Called The Epicenter. An earthquake’s most intense shaking is often felt near the epicenter. However, the vibrations from an earthquake can still be felt and detected hundreds, or even thousands of miles away from the epicenter.

Countries Most Hit By Earthquake

Japan

Located in the Pacific Ring of Fire, an area around the Pacific Ocean that is prone to tectonic activity and earthquakes, Japan is first on the list. Due to daily activity, it has developed a technology able to detect even the smallest of earthquakes.

Fitted with over 1,000 seismometers around the island, researchers show that the majority of the earthquakes are small and not felt by residents, but occasionally a larger earthquake strikes that can cause damage or even loss of life.

Japan also has a nationwide system to notify its residents of an impending earthquake, so they are ready. It is still important for residents to prepare with emergency supplies, a disaster plan, and escape routes in case of an earthquake or other natural disaster.

Indonesia

Indonesia experiences earthquakes that are larger than 6.0 magnitude nearly every year, making it one of the most earthquake-prone countries in the world.

In 2018, nine earthquakes larger than 6.0 shook the country, resulting in thousands of lost lives.

Due to its location on the Pacific Ring of Fire, Indonesia is also vulnerable to volcanic activity, droughts, floods, and tsunamis.

China

China has a long history of devastating earthquakes that have claimed thousands of lives. In 2008, a 7.9 magnitude earthquake struck Sichuan Province and left over 87,000 people dead or missing. It was the 18th deadliest earthquake of all time.

There are many reasons why China is so prone to earthquakes. It sits on top of several active tectonic plates that constantly shift and grind against each other, putting stress on the land below.

Additionally, China has many mountainous regions that are susceptible to landslides and other geological disturbances, which can trigger earthquakes in nearby areas.

The Philippines

With its position along the Pacific Ring of Fire, the Philippines is one of the most earthquake-prone countries in the world.

Due to its mountainous geography, earthquakes can also trigger deadly landslides.

In addition, typhoons and tropical storms are common. Because of these frequent and severe natural disasters, many people living in the Philippines take steps to ensure their safety by building strong structures.

Iran

Iran is one of the most earthquake-prone countries in the world, with a history of devastating earthquakes that have killed thousands of people over the years.

Due to its location along several plate boundaries and fault lines, Iran experiences a high frequency of seismic activity, resulting in rough terrain and unstable buildings.

One of the worst quakes to hit Iran was in the Gilan province. This quake in 1990 claimed over 40,000 lives. Despite this terrible tragedy, Iranians continue to live in this beautiful country because they know how to prepare for natural disasters like earthquakes.

Tremors from an earthquake in Iran once rattled Dubai residents as they evacuated homes and offices as a safety precaution.

Turkey

Located on the Anatolian peninsula between the Balkans and Eastern Europe, Turkey is frequently hit by seismic activity due to its location near several major fault lines.

Sandwiched between the Eurasian Plate and the African and Arabian Plates, a good portion of the country experiences some level of tremors each year. Undeterred by this risk, many people still choose to live in Turkey, drawn by its rich culture and beautiful natural scenery.

Peru

Peru sits at the heart of the Ring of Fire and regularly experiences small tremors as well as moderate and major earthquakes. These quakes can cause significant damage to buildings and infrastructure, putting lives at risk. This country takes these types of disasters seriously, conducting nationwide earthquake drills to help prevent loss of life.

U.S.A

At first glance, the US may seem like an unlikely candidate for being one of the world’s most earthquake-prone countries. After all, it is not located in a traditionally earthquake-prone region. However, what makes the US so vulnerable to earthquakes is its unique geological landscape.

One of the main factors contributing to the US’s high risk of earthquakes is its position along several major fault lines, including the San Andreas Fault and New Madrid Fault. These highly active fault lines run through much of the western part of the country, putting millions of people at risk.

Another key factor contributing to the US’s high risk of earthquakes is its high population. With a total population of over 300 million people, the US has one of the highest populations in the world.

This means that even relatively small earthquakes can cause significant damage and loss of life, due to the large number of people affected by them.

Italy

With a landscape that consists of rugged mountain ranges, inactive volcanoes, and coastal plains, Italy is prone to seismic activity due to its location on multiple fault lines.

Namely, the Eurasian Plate, surrounded by the Aegean Sea Plate, the Adriatic Plate, and the Anatolian Plate.

Some Of The Most Devastating Earthquakes To Hit Italy Have Included The 1908 Messina Earthquake, Which Killed Over 75,000 People, And The 1980 Irpinia Earthquake, Which Resulted In More Than 2,400 Deaths.

Despite these tragic events, Italians continue to live and work in areas that are at risk for future earthquakes.

Mexico

Like many countries located along the Pacific Ring of Fire, Mexico is vulnerable to regular seismic activity.

Thankfully, the country has strict building codes and emergency procedures in place to minimize damage during an earthquake or other natural disaster.

But it is still important for residents to help their communities stay prepared by participating in drills, keeping emergency supplies on hand, and knowing what to do if an earthquake strikes.

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ECONOTES

Stay Safe During an Earthquake

  1. Drop. Cover. Hold on.

In most situations, you can protect yourself if you immediately:

  • DROP down onto your hands and knees before the earthquake knocks you down. This position protects you from falling but allows you to still move if necessary.
  • COVER your head and neck (and your entire body if possible) underneath a sturdy table or desk. If there is no shelter nearby, get down near an interior wall or next to low-lying furniture that won’t fall on you, and cover your head and neck with your arms and hands.
  • HOLD ON to your shelter (or to your head and neck) until the shaking stops. Be prepared to move with your shelter if the shaking shifts it around.
  • If you are inside, stay inside.

DO NOT run outside or to other rooms during an earthquake. You are less likely to be injured if you stay where you are.

To reduce your chances of being hurt, take the following actions:

  • If possible, within the few seconds before shaking intensifies, quickly move away from glass, hanging objects, bookcases, china cabinets, or other large furniture that could fall. Watch for falling objects, such as bricks from fireplaces and chimneys, light fixtures, wall hangings, high shelves, and cabinets with doors that could swing open.
  • If available nearby, grab something to shield your head and face from falling debris and broken glass.
  • If you are in the kitchen, quickly turn off the stove and take cover at the first sign of shaking.
  • If you are in bed, hold on and stay there, protecting your head with a pillow. You are less likely to be injured staying where you are. Broken glass on the floor can cause injuries if you walk or roll onto the floor.
  • DO NOT stand in a doorway. You are safer under a table. 

In modern houses, doorways are no stronger than any other part of the house. Doorways do not protect you from the most likely source of injury − falling or flying objects.

Most earthquake-related injuries and deaths are caused by falling or flying objects (such as TVs, lamps, glass, or bookcases), or by being knocked to the ground.

  • Move away from windows and outside walls.
  • Stay in the building.
  • DO NOT use the elevators. The electricity may go out, and the sprinkler systems may come on.
  • If you are trapped, stay calm. Try to get someone’s attention by tapping on hard or metal parts of the structure. Doing so may increase your chances of being rescued.
  • If you are inside a crowded place, drop, cover, and hold on.
  • Do not rush for the doorways. Others will have the same idea.
  • Move away from display shelves containing objects that may fall.
  • If you can, take cover and grab something to shield your head and face from falling debris and glass.
  • If you are outside, stay outside.
  • Move away from buildings, utility wires, sinkholes, and fuel and gas lines. The greatest danger from falling debris is just outside doorways and close to outer walls of buildings.
  • Go to an open area away from trees, telephone poles, and buildings. Once in the open, get down low and stay there until the shaking stops.
  • The area near the outside walls of a building is the most dangerous place to be. Windows, facades, and architectural details are often the first parts of the building to collapse. Stay away from this danger zone.

7. If you are in a moving vehicle, stop as quickly and safely as possible.

  • Move your car to the shoulder or curb, away from utility poles, overhead wires, and under- or overpasses.
  • Stay in the car and set the parking brake. A car may jiggle violently on its springs, but it is a good place to stay until the shaking stops.
  • Turn on the radio for emergency broadcast information.
  • If a power line falls on the car, stay inside until a trained person removes the wire.
  • When it is safe to begin driving again, watch for hazards created by the earthquake, such as breaks in the pavement, downed utility poles and wires, rising water levels, fallen overpasses, or collapsed bridges.
  • If you are in a stadium or theater, stay in your seat. Protect your head and neck with your arms or any way possible.
  • Do not leave until the shaking is over.
  • Walk out carefully watching for anything that could fall during the aftershocks.
  • If you are near the shore, drop, cover, and hold on until the shaking stops.
  • If severe shaking lasts 20 seconds or more, immediately evacuate to high ground as a tsunami might have been generated by the earthquake.
  • Move inland 2 miles (3 kilometers) or to land that is at least 100 feet (30 meters) above sea level immediately. Don’t wait for officials to issue a warning.
  • Walk quickly, rather than drive, to avoid traffic, debris, and other hazards.
  1. If you cannot drop to the ground, try to sit or remain seated so you are not knocked down.
  • If you are in a wheelchair, lock your wheels. Remove any items that are not securely attached to the wheelchair.
  • Protect your head and neck with a large book, a pillow, or your arms. The goal is to prevent injuries from falling down or from objects that might fall or be thrown at you.
  • If you are able, seek shelter under a sturdy table or desk. Stay away from outer walls, windows, fireplaces, and hanging objects.
  • If you are unable to move from a bed or chair, protect yourself from falling objects by covering up with blankets and pillows.
  • If you are outside, go to an open area away from trees, telephone poles, and buildings, and stay there.

Predicting Earthquakes: A Possible Breakthrough Using GPS Measurements?

When it comes to predicting earthquakes, seismologists have long searched for a reliable precursor, a telltale sign that precedes a seismic event.

However, up until now, no such precursor has been found, leading many scientists to believe that it may never be possible. But recently, two researchers may have made a significant breakthrough in this field.

Quentin Bletery, a seismologist at the Institut de Recherche pour le Développement and the Université Côte d’Azur in France, along with colleague Jean-Mathieu Nocquet, turned to a dataset from the University of Nevada at Reno.

This dataset recorded GPS positions every five minutes from thousands of stations around the world, allowing scientists to detect even the slightest ground motions.

By focusing on GPS stations located near known earthquake locations with magnitudes of 7.0 or higher, Bletery And Nocquet Analyzed The Recorded Positions Of These Stations During The 48 Hours Leading Up To Each Respective Quake.

They compared the actual motion observed with the expected motion caused by the earthquake.

What they discovered was that in the final two hours before an earthquake, the ground’s motion often began to align with the expected motion and this alignment intensified as the time of the quake approached. This pattern was not observed in randomly selected two-hour windows without earthquakes.

These findings suggest that the motion observed in the final two hours may contain the long-sought-after earthquake precursors.

However, The Current Technology Is Not Sensitive Enough To Detect These Precursors Before The Earthquake Actually Occurs.

According to Bletery, the existing equipment would need to be 50 times more sensitive to detect a precursor to just one earthquake.

In the future, adding more GPS stations may help improve the detection and prediction of earthquakes.

However, it is important to note that while this research shows promise, seismologists still have a long way to go before transforming these findings into a reliable method of earthquake prediction.

Nonetheless, these findings highlight the potential progress being made in the field and the fascinating complexity of earthquakes.

In Summary

It is important to stay aware of any seismic activity in your area and know what to do if this risk becomes a reality.

By taking steps like participating in drills and emergency preparedness programs, keeping emergency supplies on hand, and knowing how to protect yourself during an earthquake or other natural disaster, you can help keep yourself and your family safe from harm.

That’s our show for today. Hope you learnt a thing or two. Remember, Cleanliness is next to Godliness, be clean in thoughts, in word, and in deed.

FOR ENVIRONMENTAL COMMENDATIONS AND CONCERNS:

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GIMALO-ANGEL OLOWOGOKE, SIGNING OUT.

ECONOTES

CLASSES OF EARTHQUAKES

• GREAT: MAGNITUDE OF 8.0 OR HIGHER; CAPABLE OF TREMENDOUS DAMAGE.

• MAJOR: MAGNITUDE 7.0 TO 7.9; CAPABLE OF WIDESPREAD HEAVY DAMAGE.

• STRONG: MAGNITUDE 6.0 TO 6.9; CAN CAUSE SEVERE DAMAGE.

• MODERATE: MAGNITUDE 5.0 TO 5.9; CAN CAUSE CONSIDERABLE DAMAGE.

• LIGHT: MAGNITUDE 4.0 TO 4.9; CAPABLE OF MODERATE DAMAGE.

• MINOR: MAGNITUDE IN THE RANGE OF 3.0 TO 3.9.

• MICRO: MAGNITUDE LESS THAN 3.0; THESE ARE THE SMALLEST QUAKES GENERALLY FELT BY PEOPLE.


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