Grade 8 Science: UNIT 2: Earth and Space

02/02/16

Earthquakes and Faults

 An earthquake is the perceptible shaking of the earth’s crust, resulting from the sudden release of energy beneath the planet.

 A fault is commonly the source of earthquakes. Its appearance is a significant displacement of landscape as a result of mass movement.

Activity I: Earthquakes and Faults

Simulate a fault line

• §  Pour a small mound of sand on two pieces of paper.
• §  Flatten the top of the mound with a ruler.
• §  Draw a Line at the centre of the mound.
• o   The fault line expands if you move the paper.
• o   Move the paper and you will see that the “fault” is being disfigured.

Activity 2: Stick ‘n Slip

Simulate an Earthquake

•    Attach two small boxes with a small tape.
•   Attach a rubber band to one of the boxes.
•  If you pull the rubber band to the opposite direction, you will see that the “fault” at the center will stretch.

02/09/16

 Activity 3: Stick ‘n Slip

 Simulate earthquake using clay and rulers.

•       Attach a bit of clay between two rulers
•    Shake and bend the rulers
•       Too much bending will result the clay to snap and be disrupted.

   The energy released from inside the Earth disrupts the landscape. Friction holds the landscapes together. When too much movement occurs, the landscape snaps and vibrates. These vibrations, of sudden energy release, travel in all directions and causes earthquakes.

   02/16/15

   How strong is an Earthquake?

    An earthquake may be described in two ways: intensity and magnitude. The  intensity of an earthquake gives us an idea of how strong or weak the  shaking is. The Philippine Institute of Volcanology and Seismology  (PHIVOLCS) uses the following scale to describe the intensity of    earthquakes in the Philippines.

I – Scarcely Perceptible	Felt under favourable conditions. Delicate objects sway slightly.
II – Slightly Perceptible	Felt indoors. Objects move slightly. Water oscillates weakly.
III – Weak	Felt indoors and outdoors. Objects move noticeably. Water oscillates considerably.
IV – Moderate	Felt indoors and outdoors. Objects move considerably. Water oscillates.
V – Strong	Vibration is felt indoors. Objects move violently.
VI – Very Strong	Vibration is felt indoors and outdoors. Objects move violently. Weak structures suffer slight damage.
VII – Destructive	Vibration is felt everywhere. Rockslides occur. Weak structures suffer considerable damage.
VIII – Very Destructive	Vibration is felt everywhere. Rockslides occur. Well-built structures suffer noticeable damage.
IX – Devastating	Vibration is felt everywhere. Rockslides and liquefaction occur. Well-built structures suffer total damage.
X – Completely Devastating	All man-made structures are destroyed. Massive landslides and liquefaction, large scale subsidence and uplift of land forms and many ground fissures are observed.

     
  03/01/13

What’s inside the Earth?

The shaking of an earthquake starts from the Focus, or the source underneath the ground. Once an earthquake happens, vibrations will be released and will spread out. These vibrations are more properly called Seismic Waves. These released waves will travel through the body of the earth and speed up when it travels deeper. At certain depths, the s-waves are reflected or refracted which indicates that the earth is layered.

Thus, earthquake waves give us a picture of the Earth’s interior, the way an “ultrasound” provides an image of a baby inside the womb. This is why scientists know a bit about the interior of our home planet, even if no one has gone deep into the Earth yet.

Understanding Typhoons

A typhoon is a mature tropical cyclone that develops in the western part of the North Pacific Ocean between 180° and 100°E. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting for almost one-third of the world's annual tropical cyclones.

According to the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), about 20 tropical cyclones enter the Philippine Area of Responsibility each year. We have to be knowledgeable about tropical cyclones if we want to prevent the loss of more lives.

If the wind speed is less, from 119 to 200 kph, then it is called a typhoon. If the wind speed is between 65 and 118 kph, it is called a tropical storm. And when the wind speed is between 35 to 64 kph, it is a tropical depression.

    03/22/16

Activity 1: Plotting the PAR

 Identify the Coordinates

·        5N, 115E

o   Brunei

·        15N,115

o   South China sea

·        25N,120E

o   China

·        25N, 125E

o   Taiwan

·        5N, 135E

o   Pacific Ocean

Tropical cyclones need water to form, especially oceans. But not all parts of the ocean could provide water vapor. Thus, typhoons need warm oceans to form. According to scientists, temperature of the ocean must be 25.6 degrees in order to form. From the maps, you can see that tropical cyclones generally move in a northwest direction.  The reason is because there are large-scale winds that push the tropical cyclones in that direction. This is similar to the way a whirlpool is carried along by a flowing stream.   As you can observe, all four tropical cyclones struck the northern part of the Philippines. Now you know why the southern part of the Philippines is often untouched by tropical cyclones. Three of the tropical cyclones mentioned above weakened and died out near land. Agaton dissipated in Luzon, Yoyong in Taiwan, and Huaning near Mainland China. This means that when tropical cyclones reach land, they die out because they are cut off from the warm ocean waters that keep them going.

  Activity 2: Tracking a Typhoon

  Track the activities of the typhoon “Sendong”

·        Typhoon “Sendong”

o   Formed: 12/13/06, Western Pacific Ocean

o   Entered:12/18/06, PAR

o   Left: 12/19/12

o   Direction: Northwest

Sendong started out in the Pacific as an area of low pressure. Because it was just a low-pressure area, it was not given a name. Then it intensified into a tropical depression. Again it was not yet given a name because it was still outside the PAR.

When it finally entered the PAR, it had already strengthened into a tropical storm. Since it was within the PAR by then, PAGASA gave it a name—Sendong—from its prepared list. Internationally, the tropical storm was called Washi.

Sendong brought hours of torrential rains to Mindanao. Some places received more than 200 mm of rain. Because of the excess rain, flash floods and landslides took place. Nearly a thousand people were killed, many in the cities of Cagayan de Oro and Iligan. Damage to houses, roads, and bridges reached up to 2 billion pesos.

Tropical cyclone Pablo(international name, Bopha) was    so strong it was categorized as a supertyphoon.

    03.29.16

 When a tropical cyclone enters the Philippine Area of Responsibility (PAR), warnings from the Philippine Atmospheric, Geophysical and Astronomical Services Administration PAGASA will be issued to warn about the oncoming danger. These warnings are classified into 4 signals.

Philippine Signals
Signal #1	Wind speed: 30-60 kph	Irregular rains expected to be in 36 hours.
Signal  #2	Wind speed: 60-100 kph	Irregular rains expected to be in 24 hours.
Signal #3	Wind speed: 100-186 kph	Irregular heavy rains expected to be in 18 hours.
Signal #4	Wind speed: 187(above) kph	Very heavy, irregular rains expected to be in 12 hours.

04/06/16

Comets, Asteroids, and Meteors

Recent advances in space technology have allowed scientists coming from different background such as physics, chemistry, biology, and geology to collaborate on studying Near-Earth Objects (NEO) such as comets and asteroids.

With more powerful telescopes and space probes, the study of comets and asteroids provides more clues about the origins of our solar system. Over the past three years, amateur and professional astronomers have discovered several NEOs that came close to Earth, the most recent asteroid being Asteroid 2012 DA14.

It made a very close approach to Earth as it orbited the Sun on February 16, 2012 (Philippine Time). In the morning of the same day, an asteroid entered Earth’s atmosphere and exploded over Lake Chebarkul in Russia hurting about 1,000 people in the process

Activity 1: What if an Asteroid Hits the Earth?

·         Simulate an asteroid impact

o   Using a tray filled with flour, hold some pebbles and throw them into the flour.

§  You will observe that the pebbles that crashed into the flour would create round, irregular craters.

§  In a real life situation, an asteroid impact will do vast damage to the crash site. The explosion created would also cause profound casualties if it’s near a populated area.

Comet		Asteroid
Kuiper Belt/Oort Cloud	Origin	Asteroid Belt
Varied/Irregular	Flight Pattern	Varied/Irregular
Ice/Carbon	Components	Silicate/Stone/Metal
Highly Elliptical	Shape	Irregularly Elliptical

Comets and asteroids have both irregular shapes and sizes. Both reflect light from the sun because of the presence of silicate, much like the moon. Comets are found mostly in the Kuiper belt, while asteroids are found in the main Asteroid Belt. The most famous comet is the Hailey’s Comet which appears every 75- 76 years, while Chelyabinsk Asteroid is popular for crashing into Russia. It was theorized that asteroids helped the formation of earth.

04.12.16

Activity 2: Asteroid, Meteoroid, Meteorite

  

A shooting star appears as a comet. It travels in high speeds, with a bright tail attached to it. A shooting star is another name for a meteor. But the truth is: a meteor is not a star at all. A meteor is a light phenomenon or a streak of light that occurs when a meteoroid burns up as it enters Earth’s atmosphere. A meteoroid is a broken up rock and dust from either a comet, asteroid, the Moon, or from Mars.

A meteoroid can be as small as a grain of sand or as big as a boulder. When it enters Earth’s atmosphere, the air in front of the meteoroid heats up, causing materials to burn up. From Earth, these glowing materials appear as a streak of light or a fast-moving bright object that appears to have a tail just like a comet. What differentiates the two when we see them in the sky is that a comet moves slowly and appears in the sky for a longer time. A meteor moves swiftly and seems to fall on the ground. It “shoots” from a point in the sky, making people think that it is a shooting or falling star. Also, a comet is difficult to see with the unaided eye because it is farther from Earth compared to a meteoroid entering Earth’s atmosphere. Sometimes, a comet can be bright enough to be seen by the unaided eye, but this is rare, such as in the case of Comet Hale-Bopp.

 

The number of meteors that can be seen during a meteor shower vary. It starts with the appearance of a few meteors per hour, increasing in frequency until it reaches its peak of 1-2 meteors per minute, and then declines. The dates in the peak month vary and astronomers make forecasts of the peak days (usually lasting for three days) every year.

Usually, the meteoroids that cause meteor showers come from comets, but they may also come from an asteroid like in the case of the Geminids. Earth passes through Asteroid3200 Phaethon’s orbit where some fragments from the asteroid are found. Once these fragments enter Earth’s atmosphere, they burn up. Meteoroids from comets appear fuzzy because of the ice particles while those from asteroids are clearer and distinct because they do not have these ice particles.