Category Archives: Earth

Plate Tectronics

Cut Away of Earth's Crust
Cut away schematic of the Earth, By derivative work: Anasofiapaixao Earth_internal_structure.png: USGS (Earth_internal_structure.png) [Public domain], via Wikimedia Commons
According to the theory of plate tectonics, the earth’s lithosphere contains plates that move gradually over the asthenosphere. The major geological processes, such as earthquakes and the formation of volcanoes and mountain belts occur at the places of the interaction of these plates. As a result, the following changes have been witnessed in the earth’s geology:

The formation of the Himalayas – when the Indian subplate burrowed under the Eurasian plate, or the formation of the Appalachian Mountains, when the North American and African plates collided. The separation of North America from Europe by the opening of the Atlantic.

The volcanic and seismic activity of the West Coast of the US occurs as a result of grinding of the North American and Pacific plates.
The above mentioned are just a few examples of the effects of plate tectonics. The geological history of earth is littered with such phenomena and processes that have made the Earth how it is today.

The Latest Findings

But as it turns out, such interactions between continental plates is not the only reason for various geological processes. Research led by a joint team of the University of Toronto and University of Aberdeen researchers has achieved an enormous breakthrough! According to the research that uses supercomputers to run a model of the Earth’s upper mantle and crust, the prehistoric geological events could have left deep ‘scars’ that may play a significant role in earthquakes, tsunamis, formation of mountains or ocean trenches and many other ongoing geological processes.

The models created by the researchers indicate that the previous plate boundaries could stay buried deep below the surface of the Earth. These structures, which are no less than many millions of years old, are located far from the current plate boundaries and may cause drastic changes in the surface properties and structure of the interior of the continents.

The researchers went a step further to propose a new map highlighting the ancient geology of the Earth. The ‘perennial plate tectonic map’ explains through illustrations how the prehistoric geological events could affect today’s geological processes. The map is based on the common tectonic map, which is taught in elementary school, but it has been modified to include the concealed, ancient plate boundaries that may be involved in plate tectonic activity in the past as well as the present.

Owing to this recent breakthrough, some major revisions are required to the fundamental idea of plate tectonics. The research paper titled, ‘Lasting mantle scars lead to perennial plate tectonics’ appeared in Nature Communications issue of June 10, 2016.

The Science Behind Earthquakes

We’re all familiar, or at least come across time and again, with the terms tectonic plates, fault lines and seismic zones. But there are quite a few of us who cannot make up the connection between these and basically answer the simple question of what causes earthquakes? How and why the tectonic plates move and what is it beneath the surface of the earth that makes all these hazardous movements to happen’ are two of the most pressing questions related to earthquakes.

Keep reading to get the aforementioned questions answered and get your hands on some essential knowledge about the basics of earthquakes.

Tectonic plates and fault lines

The planet Earth is composed of four layers, inner and outer core, mantle and the crust which is the outermost core. The outer/top-most part of the plastic-like mantle and crust make up a thin layer over the surface of the earth. In order to understand tectonic plates, it is essential to know that this thin outer layer is not a single piece; rather it is a number of pieces joined together. These pieces of crust, called tectonic plates, together with the block of the earth right beneath them, are not static; they move and slide at their boundaries against each other.  These boundaries are referred to as ‘plate boundaries’. When we say the word fault line, we are basically referring to these boundaries collectively. It is here that the blocks of earth slide past each other causing the earthquake.

So, how does an earthquake happen?

As mentioned above, tectonic plates are not static. As their boundaries are joined or stuck with each other, it is easier for the plate itself to move than the respective boundary to move at the same pace because of higher friction. As plates move, pressure builds up on the plate boundaries causing energy to be increasingly stored in them. It is only when the pressure build-up from the plates’ movement overcomes the friction between the jagged plate boundaries that they are unstuck and slide past each other. This releases the energy being stored for far too long. The radiation of this released energy across the tectonic plate is what is scientifically called ‘Seismic Waves’. As these waves move past the earth, they shake the earth. Upon reaching the surface, they shake the surface of the earth.

The area below the surface of the earth, the origin of the earthquake, is called the hypocenter. Its corresponding area right on the surface of the earth is called epicenter. The path that the seismic waves travel from the hypocenter and epicenter is basically the fault plane, the movement of which against the neighboring plane causes the earthquake.

Breaking misconceptions

One major misconception about earthquakes is that the tectonic plates move only before/during the earthquake. This is not true. It is totally natural for the tectonic plates to keep having slight movements at all times, which do not escalate into an earthquake. As established above, it is only when the movement of tectonic plates is significant enough to overpower the friction holding the boundaries together that earthquake happens.

Mighty Tornadoes and What Makes Them So Twisted!

Tornado in California
Twister moving in California

Natural disasters are a grave reminder of how helpless man is against the forces of nature. Tornadoes are just one of the many destructive forces of nature that can uproot you within seconds and throw you around like cardboard chips. Hence, it is important to know and learn about them as much as we can to make sure we are at least better equipped mentally to face the deadly aftermath of this catastrophe.

So what exactly is a tornado?

According to the National Weather Service, a tornado is

“A violently rotating column of air pendant from a thunderstorm cloud and touching the ground”

It is basically a moving column of violent air that is connected with the ground and a cumulonimbus cloud (in most cases) as the same time. In the United States, there are around a 100,000 thunderstorms that form within a year’s’ time; and there are 600 to 1,000 thunderstorms each year that bring tornadoes with them.

Tornadoes can form in almost any state; but the states that are most affected include Texas, South Dakota, Oklahoma, Nebraska, Missouri, Mississippi, Louisiana, Kansas, Iowa, Indiana, Illinois, Georgia, Florida, Arkansas, and Alabama.

So how much do you know about tornadoes? Let’s find out!

These destructive machines of nature are a weather-related event. Normally, a tornado’s path of expected to be around four hundred yards wide and four miles long. But don’t be fooled! Some tornadoes may surprise you with a hundred-mile long path and about a mile wide! They can reach a height of about 60,000 feet – you think the Giant in “Jack and the Beanstalk” would have been that tall or is it just us?

A tornado can move at an average speed of between twenty five and forty miles per hour, but there are some that can chase you at an astounding seventy mile per hour speed. And that’s just the tornado; the winds inside it have a speed of their own – let’s say they can swirl around at almost three hundred miles per hour. There is no way you can beat that!

If we observe the average stay of a tornado on the ground, it is hardly ever more than an interval of about five minutes, but the tornado keeps returning to the ground, and the touchdown could be several times in a row!   

So which direction do these tornadoes move in? Allow us to enlighten you.

These tornadoes really have a strong sense of direction – we mean, how else would the tornadoes rotate clockwise in the southern hemisphere and counterclockwise in the northern hemisphere? Also most tornadoes are founding moving to the northeast from the southwest.

Another interesting fact about tornadoes is that a majority of them occur in the time span between 3PM and 7PM. Although these tornadoes occur across the globe in many different countries, United States gets the largest share of them, and they’re also the most destructive ones to occur. On an average, the United States faces almost eight hundred tornadoes each year.

Do you know how many people are killed by tornadoes each year? The figure comes around ONE HUNDRED!

 

Is There Anything Scarier than a Tsunami?

What on earth scares you? (Pun intended).

Many would answer war, hunger, terrorism, poverty, and even death. Things like these make the havoc wrecked by natural disasters quite puny. Every once in awhile we hear about a cyclone killing hundreds, a volcanic eruption that destroys villages, a severe earthquake that brings mass destruction and deaths, or a tsunami that just sweeps away entire towns with it.

Natural disasters are a reminder that we are only human. That even the best defenses cannot save us from the forces of nature. And the tsunami happens to be one of the most fascinating natural disasters to study.

Ever wondered what causes a tsunami?

A tsunami is a sequence of oceanic waves forming due to an earthquake, a volcanic eruption, or a landslide that occurs under the surface of the sea. The underwater world is a mysterious one and yes they do have mountains down there too! There are times, although rare when these waves are the result of the impact of a giant meteor that falls into the ocean.

The waves of a tsunami can reach a height of or more than One Hundred Feet!

Tsunami is a Japanese word. It translates to “harbor wave” (tsu=harbor + name=wave). The Pacific Ocean has the “Ring of Fire” which is the most tsunami prone region in the entire world, with around 80% tsunamis occurring there – a reason why Japan has a long history of tsunamis.

However, the worst tsunami in the history occurred in the Indian Ocean back in 2004. It was caused by an earthquake that resulted from the energy radiation of twenty three thousand atomic bombs. The waves originating from the core of this tsunami wrecked havoc on the coastal areas of 11 different countries that included India, Bangladesh, Sri Lanka, Thailand, Indonesia, Malaysia, Myanmar, Maldives, South Africa, Kenya, and Somalia. The death toll reached a tragic count of 283,000 lives.   

It is observed that the first wave of the tsunami is usually not the most powerful one; the ones that follow gain strength, height, and destructive momentum. The average speed of a tsunami has been recorded around five hundred miles per hour – at that speed it can almost compete a jet plane!

In the United States, the states that are most exposed to the risk of tsunami include Washington, Oregon, Hawaii, California, and Alaska. Out of these states, it is Hawaii that is most prone to the tsunami. On an average, the state gets at least one tsunami each year and there is a severe one that hits them in every seven years. The worst tsunami to ever hit Hawaii was one that occurred back in 1946. It hit the Hilo Island at a speed of five hundred miles per hour with waves as much as thirty feet high!

Tsunamis don’t lose their energy as they travel. They could cross entire oceans without losing their momentum. Unlike other natural disasters, it is possible to predict the estimated time for the tsunami to hit. Scientists can derive that based on calculation related to water depth, distances, and the timing of the cause.

If you’re ever caught in a tsunami, don’t swim! Rather try and get hold of a floating object that can help you be carried away by the waves, hopefully to a safer place.

Earth – Third Rock from the Sun

Located nearly 93 million miles, or 1 Astronomical Unit (AU) away from the Sun, the planet Earth is the largest of the terrestrial planets—or the four rocky planets closest to the Sun in our solar system. (The rest are gas giants).

Earth is the only planet in our solar system that is not named after Greek and Roman gods and goddesses. The name Earth is at least 1,000 years old and is an English/German word that simply means ground.

It takes roughly 24 hours for the Earth to complete a full rotation, but that is gradually slowing. This deceleration is almost imperceptible, but has the effect of lengthening our days. It is happening so slowly, though, that it could be 140 million years before the length of a day increases to 25 hours.

The first photo of Earth from space was taken on October 24, 1946, by a V-2 test rocket launched from New Mexico. From there, we turned our attention to the closest body in our solar system: the Moon.

While the Moon, Earth’s only natural satellite, is only the fifth largest in our solar system, in terms of percentage of the size of the body it orbits, the Moon is the largest satellite of any planet in our solar system.

Astronomers hypothesize that the Moon was formed 4.5 billion years ago, not long after Earth, from the debris left over after a giant impact between Earth and a Mars-sized body.

The first unmanned spacecraft to reach the Moon was one from the Soviet Union’s Luna program in 1959, and the first manned lunar landing being Apollo 11 in 1969. The last manned spacecraft was Apollo 17 in 1972, and since then, the Moon has only been visited by unmanned spacecraft.

NASA started to plan to resume manned missions for the construction of a lunar base by 2024, but the program was cancelled in favor of a manned asteroid landing by 2025 and a manned Mars orbit by 2035.

What if the Earth Stopped Rotating?

Even though this is impossible, it’s still fun to think about! If the Earth stopped rotating, it would be terrible for everything that is on the surface of our planet!

The Earth rotates on its axis, moving us through space at about 1000 miles an hour for someone standing on the equator. In seconds that’s about .3 miles a second, which doesn’t seem so bad. If the Earth stopped, momentum would keep us moving at that same speed until friction slowed us down. The results would be catastrophic!

Our atmosphere is also moving at a similar speed with us. If everything suddenly stopped, it would be like an epic simultaneous hurricane on almost every part of the planet. The closer to the North and South poles however, the less damage it would cause. If you were standing on the North pole you’d hardly feel the Earth stop.

With the Earth stopped, a day would last 365 days. It would take a full year for the Earth to fully orbit the sun and bring back the Earth to the same location in the sky. Each year would consist of one long day and one long night. That means we would have 6 months of day and 6 months of night.

Our tilt gives us our seasons. A stationary planet would have no tilt. Without that tilt, there would be no seasons. It would be summer all the time. Plants and animals would inevitably die. Since our Earth turns every day, the shape of our Earth is like a ball, or to get technical, an oblate spheroid. Without that tilt, the Earth would instead be a perfect sphere. Since our Earth has a bulge in the middle, the oceans are held out by the equator at 8 kilometers out. On a perfect spherical Earth, the world’s oceans would redistribute, flooding many regions of the planet. We would end up with a single continent and oceans in the North and South poles.

As the Earth stops spinning, so would the Earth’s core. Our core produces the magnetic field that protects us from radiations from space. Cosmic rays would obliterate any life remaining on the surface of the Earth and only life underground could possibly survive.

Introduction to Noctilucent Clouds

 noctilucent clouds

People living at high altitudes often witness shining, silver-blue colored clouds during summer nights. These are known as ‘noctilucent clouds, night-shining clouds or NLCs’.

What Are Noctilucent Clouds?

Noctilucent means ‘shining at night’. The term noctilucent is specifically used to refer to the clouds that form in the highest layer of the atmosphere, known as mesosphere, and are visible during summer to people living between 45 to 60 degrees of latitude in North or South of the Equator from May to August and from November to January/ February respectively.

There are different views regarding the formation of noctilucent clouds. Some scientists believe that they are made up of ice crystals that form on fine dust particles present in space, under extremely low temperatures and in the availability of water. Others think that NLCs are indicators of global warming.

History of Noctilucent Clouds

Noctilucent clouds were first discovered in 1885 by a German T.W. Backhouse, almost 2 years after the huge volcanic eruption at Krakatoa, a volcanic island in Indonesia. They were considered as signs of the presence of volcanic ash in the Earth’s atmosphere by scientists of the time. But, the scientists were puzzled when they remained even after the volcanic ash had settled.

According to a professor at the University of Colorado Gary Thomas, “Since then, noctilucent have not only persisted, but also spread”.

noctilucent clouds diagram

Why Noctilucent Clouds Appear In Summers?

The idea that noctilucent clouds are made up of ice crystals and their appearance during summer nights seems quite contrasting. However, the scientific explanation of the process of the formation of ice crystals is as follows:

“The air that is close to the ground gets heated during summers and hence rises. As the air rises, it expands and cools down due to the decrease in atmospheric pressure with rising altitude. The air keeps cooling down with the rising altitude and ultimately reaches to the temperature as low as -134 degrees centigrade or – 210 degrees Fahrenheit in which the water vapours are transformed into ice crystals”.

How Noctilucent Clouds Become Visible From Earth?

Noctilucent clouds become visible from high altitudes on earth when the sun is just below the horizon i.e. i.e. between 6 and 16 degrees ,that happens about one and a half to 2 hours before sunrise or after sunset. At this location, although the sun goes below the ground horizon, it can still be viewed from the high altitude of NLCs. The sunlight emitting from the sun at this position, illuminates the NLCs and make them shine on the dark sky.

Although scientists have been investigated and researching about noctilucent clouds, including scientists from NASA as well, very little is known about them making these silver-blue clouds mysterious. At the same time, NLCs present great avenues for research to both existing and upcoming scientists.

The Giant Meteor Crater

meteor rcrater-arizona
Meteor Crater Arizona

50,000 years ago, out of the northeastern sky, a pinpoint of light grew rapidly into a brilliant meteor. This body was probably broken from the core of an asteroid during an ancient collision in the main asteroid belt some half billion years ago. Hurling at about 26,000 miles per hour, it was on an intercept course with Earth. In seconds it passed through our atmosphere with almost no loss of velocity or mass.

This massive iron-nickeled meteorite, or dense cluster of meteorites, estimated to have been about 150 feet wide and weighing several hundred thousand tons, struck the rocky plain with a force greater than 20 million tons of TNT.

Moving at hyper-velocity speed, this impact created immensely powerful shock waves in the surrounding atmosphere. In the air, these waves swept across the level plain, devastating all in their path for a radius of several miles. In the ground, as the meteorite penetrated the rocky plain, pressure rose to over 20 million pounds per square inch. Both iron and rock experienced limited vaporization and extensive melting. Past the melted region, an enormous volume of rock underwent complete fragmentation and ejection.

The result of these violent conditions was the excavations of a giant bowl-shaped cavity. In seconds, a crater 700 feet deep and over 4,000 feet across was carved into a once flat and rocky plain. During its formation, over 175 million tons of limestone and sandstone were abruptly thrown out to form a continuous blanket of debris surrounding the crater for over a mile. In some of the shocked meteorites, the intense pressure turned small concentrations of graphite into microscopic sized diamonds.

Photographs of our moon, the other planets and their satellites clearly show that the millions of craters on their surfaces were caused by meteorite, asteroid or comet impacts. Three decades of research in the Earth’s surface show that it too has been the target of numerous large and small collisions.

The Meteor Crater, also called the Barringer Meteorite Crater, represents the most basic type of impact crater in the solar system. Collision and impact processes play a dominant role in the development of our planets, satellites, asteroids and comets. The geological and planetary records are clear; collisions have occurred since the beginning of the solar system and will continue to occur!

Understanding the Earth Systems

Satellite_Image_of_Earth's_Interrelated_Systems_and_Climate
The Earth’s systems consist of the atmosphere and the layers within the Earth’s surface.

Earth science is an important part of geology. Earth science deals with the physical composition of the earth and its atmosphere. Without understanding this branch of geology, knowing how the earth works is not possible. Earth science involves many aspects, including the earth’s atmosphere and rock formations, and it is here where we will be focusing our attention.

Earth system

Five interconnected parts compose the Earth’s atmosphere. The collection of materials and processes of one part are different from that of the other. However, they are not independent, as each part interacts with the other. 

A number of gasses make up the earth’s atmosphere including 78% nitrogen, 21% oxygen and 1% other gasses. The atmosphere is present way above the earth’s surface and becomes thinner as it reaches the space. The earth’s atmosphere consists of five layers. The first of these layers is where weather and clouds are found.

All the life present on earth is known as biosphere. This includes all things that inhibit the earth including remains of the deceased. All the life present on land and in the ocean such as plants, animals, fungi, bacteria, etc. make up the biosphere of the earth.

Consisting of all of the rocks of the earth’s crust, whether it is the rock that lies underneath the crust, the rock near the earth’s core or the core itself, comprise the lithosphere and is the planet’s solid outer core. The Lithosphere is where major catastrophes such as earthquakes and volcanoes occur.

Hydrosphere is all the water that the earth encompasses including all the oceans, rivers, lakes, streams, groundwater, water vapor, and even a pool of water. About seventy percent of the earth’s surface is covered with water and a good part of this water is the ocean. Water is a major necessity of life whether it is used for drinking, cooking, cleaning or agriculture purposes.

Finally, we come to the cryosphere. Cryosphere includes all of the planet’s frozen areas such as snow, glaciers, and ice present in the sea. Covering the earth’s surface, Cryosphere is usually visible during the winters.

 

 

Understanding Earthquakes and How They Occur

Sitting on your study table, doing your homework and suddenly the surface beneath the table starts shaking, subsequently moving everything present on the table. What’s happening? It may be an earthquake taking place. What is an earthquake?

If you want to know how natural disasters occur, then you need to take a deeper look into geology.  The study of geology consists of many natural phenomena, including volcanoes and earthquakes. The latter is what we’re going to focus on.

Understanding Earthquakes

The rumblings and shaking of the earth’s surface is known as an earthquake. Energy can build up over a prolonged period of time beneath the earth’s surface, resulting in tension caused by two blocks of the earth suddenly slipping or breaking past one another. You can feel an earthquake as a shock under your table or feet. So what causes earthquakes to occur? Let’s take a look.

How Earthquakes Occur

The earth’s surface and submarine levels make up the earth’s crust and it is here where earthquakes occur. Massive energy is present in the earth’s inner part while some of it breaks free via volcanic activity and cracks; much of it is hoarded within the inner parts present in the crust.

The energy hoarded here results in the plates pushing up against one another. This activity is known as tectonic plates. There is massive pressure on the fault lines and immense plate’s tension due to the energy that has built up and the movement after a period of time. The fault line gives away and the plates shift. The plates move either apart from or against each other as the energy that has built up causes intense pressure.

In the form of water ripples known as seismic waves, an earthquake occurs at this point of time. On reaching the surface, these waves cause the ground to shake causing damage to everything present on it.

Types of Earthquakes

Earthquakes occur in three different forms. Following are the different types of earthquakes.

Convergent Boundary

A thrust fault is created during movement causing one plate to move against the other, the place where it occurs is known as a convergent boundary.

Divergent Boundary

A rift zone is formed when plates are forced apart from each other. The place where this occurs is known as a divergent boundary.

Transform Fault

The plates slip by each other at a transform fault.

There you have—what is an earthquake and how it occurs. Finally, a word of advice: the next time the surface under your study table moves, don’t just sit there, take the precautionary measures because you never know, it I might be an “Earthquake.”