Earthquakes, Volcanism, and Earth’s Interior

Question 1

The pattern that appears when the actual brightness (or absolute magnitude) and color (or color index) of many stars are plotted against each other.

Answer 1

Hertzsprung-Russell diagram

Question 2

Our Sun lies within a spiral galaxy known as the Milky Way Galaxy, which is estimated to contain _____ stars.

Answer 2

200 to 400 billion stars

Question 3

Temperature within the Sun is estimated to be about ____________.

Answer 3

17,000,000°C

Question 4

Four types of processes that appreciably affect planetary surfaces:

Answer 4

1. Impact cratering 2. Volcanism 3. Tectonism 4. Atmosphere

Question 5

A short-lived burst of very high energy waves from the gamma-ray portion of the electromagnetic spectrum.

Answer 5

gamma ray burst

Question 6

This theory explains the occurence of earthquakes based on the relationship between stress and strain and the deformation of
rocks.

Answer 6

Elastic Rebound Theory

Question 7

The Mercalli intensity scale ranks from:

Answer 7

I-XII

Question 8

___________________ is a seismic scale used and developed by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) to measure the intensity of an earthquake. It was developed as a response to the _____________ (magnitude 7.7) and was adopted in the Philippines in 1996 replacing the ________________. Intensity scale ranges from _______ , with ___ classified as completely
devastating

Answer 8

Philippine Earthquake Intensity Scale (PEIS), 1990 Luzon Earthquake, Rossi-Forel Intensity Scale, I to X, X.

Question 9

What type of fault is the North Bohol Fault (NBF)?

Answer 9

Reverse Fault with minor right- and left-lateral displacement. (where right is more dominant)

Question 10

Most magma that erupts on the Earth’s surface is ________ in composition and has a temperature of __________.

Answer 10

Basaltic, 1000degC to 1250degC.

Question 11

Magma of a basaltic composition is the result of the partial melting of what type of rock?

Answer 11

Peridotite

Question 12

It is formed when large volumes of basaltic
lava will flow onto the surface along large fracture zones.

Answer 12

Continental flood basalt

Question 13

Differentiate aphelion and perihelion to apogee and perigee.

Answer 13

Aphelion - greatest distance between planet and sun. Perihelion - closest distance between planet and sun. Apogee - moon furthest from the earth (tidal range are less). Perigee - moon closest to the earth (tidal range are high).

Question 14

Differentiate spring tide and neap tide.

Answer 14

Spring tides occur when the sun, moon, and Earth are lined up, and this causes regular high tides and low tides to be much higher. Neap tides occur when the sun, moon, and Earth form a right angle, and this causes the regular high tides and low tides to become much lower than usual.

Question 15

International Astronomical Union (IAU) said that the definition for a planet is now officially known as “a celestial body that:

Answer 15

a) is in orbit around the Sun b) has sufficient mass for its selfgravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape c) has cleared the neighborhood around its orbit.

Question 16

Differentiate comets, asteroids, meteoroids, and meteorite.

Answer 16

• Comets are relatively small bodies, 0.6 to 6 miles (1–10 km) in diameter, composed of small rocky fragments embedded in a mass of ice and frozen gases. • Asteroids are small bodies that orbit the Sun, but are different in that they are composed primarily of rocky and metallic materials. Most asteroids lie in what is known as the main asteroid belt between Mars and Jupiter • Meteoroid - a body of rock and/or metal that is smaller than a planet or asteroid • Meteorite - a solid piece of debris that originated in outer space and survived its passage through the atmosphere to reach the surface of a planet or moon

Question 17

Why is Allende is often called “the best-studied meteorite in history.“

Answer 17

It contains chondrules and CAIs that are estimated to be 4.567 billion years old, the oldest known solids to have formed in the Solar System

Question 18

List the six meteorites from the Philippines in the Meteoritical Society’s Bulletin Database in increasing order of mass.

Answer 18

Ponggo - Pantar - Pampanga - Paitan - Orconuma - Calivo - Bondoc

Question 19

Differentiate seismometer, seismograph, and seismogram.

Answer 19

Seismometer – the instrument used to detect seismic waves. Seismograph – a seismometer with a recording device that produces a permanent record of earth motion, usually in the form of wiggly line drawn on a moving strip of paper. Seismogram – the paper record of earth vibration.

Question 20

The depth of focus is determined in a similar procedure, and is used to classify earthquakes as:

Answer 20

1) Shallow – 0-70 km 2) Intermediate – 70-350 km 3) Deep – 350-670 km

Question 21

Compare Richter Magnitude Scale from Moment Magnitude Scale.

Answer 21

Richter Magnitude Scale (named after the seismologist, Charles F. Richter) - rates earthquakes based on the size of their seismic waves, as measured by seismographs; governed by amplitude (wave height) and distance. However, scientists eventually realized that results obtained using the Richter magnitude scale were not always consistent with one another, particularly for large-magnitude earthquakes. Moment Magnitude Scale - based on similar types of seismogram measurements as Richter’s, but is more accurate over a wide range of magnitudes and geologic conditions; based on the total amount of energy released and is determined by measuring the surface area of the ruptured fault and how far the land moved along the fault.

Question 22

Differentiate a fissure from a rupture.

Answer 22

Ruptures are upward continuation of fault-slip at depth. Fissures are smaller displacements or more distributed deformation in and around the rupture area.

Question 23

Differentiate magmatic assimilation, mama mingling, and magma mixing.

Answer 23

Assimilation - some of the surrounding rock (country rock) may be incorporated to the upwelling magma. Magma mingling is used to indicate the process of acting to disperse physically (no chemical exchanges are involved) one or more magmas within a host magma, whereas the term Magma mixing indicates that the mingling process is also accompanied by chemical exchanges. It occurs during the ascent of two chemically distinct magma bodies as the more buoyant mass overtakes the more slowly rising body.

Question 24

What are the two processes involve during magmatic assimilation. Define each one.

Answer 24

Stoping is the process by which country rock is broken up and removed by the upward movement of magma.”the magma chamber may have been largely opened by overhead stoping”. Shouldering is the process whereby solid or fluid foreign material is incorporated into the magma.

Question 25

Volcanic gas is mainly composed of:

Answer 25

water vapor (H2O), followed by carbon dioxide (CO2), and sulfur dioxide (SO2 ), which together account for over 95% of all volcanic gases

Question 26

Define volcanic mudflow.

Answer 26

Also called a lahar or debris flow, is a mixture of ash, rock, and considerable amounts of liquid water. Ash and rock may comprise 60 to 90% by weight may resemble a river of wet concrete.

Question 27

Define pyroclastic flows.

Answer 27

Pyroclastic flows are dry, hot avalanches where large rock fragments tumble along the ground surface and are overlain by a flowing cloud of finer fragments and droplets of lava. Mixed with these materials are superheated gases, creating a flow that will obliterate and incinerate everything in its path.

Question 28

Explain why rocks are much stronger under a compressional force compared to
a tensional force.

Answer 28

Because at convergent boundaries where compressive forces dominate, rocks are able to accumulate much more strain before rupturing than at divergent boundaries where tensional forces are dominant. Rocks can also accumulate considerable amounts of strain under the shear forces found along transform boundaries.

Question 29

Why is it that subduction zone earthquakes are capable of releasing unusually large
amounts of energy.

Answer 29

(1) the way the overriding plate buckles and becomes locked. Another key factor is that (2) the surface area over which the slippage or rupture occurs can be quite large compared to that in other plate settings. (3) the descending oceanic plate is relatively cool, which makes the rocks more brittle and capable of accumulating more strain before rupturing. (4) some of this energy can be transferred to the ocean, creating tsunamis that reach heights of 100 feet (30 m) as they crash into coastal areas.

Question 30

Explain the mechanism of Intraplate Earthquakes.

Answer 30

These earthquakes that occur far from a plate boundary or active mountain belt and are generally believed to be related to tectonic forces that are being transmitted through the rigid plates. These forces cause crustal rocks to slowly accumulate strain, which is then released along buried fault systems, producing earthquakes in the interior of continents.

Question 31

Explain how natural vibration frequency and resonance affects the movement of a building during an earthquake.

Answer 31

Natural vibration frequency – refers to the vibration of a structure/building at a fixed frequency; frequency is the number of times the motion is repeated in a set amount of time.As building height increases, the natural vibration frequency decreases—similar to how lengthening a guitar string will produce a note with a lower or deeper pitch. When a building’s natural vibration frequency matches the frequency of seismic waves, resonance can occur, causing a building to sway more violently. Because vibration frequency varies with height, not all multistory buildings will experience resonance.

Question 32

Explain how ground amplification affects the energy of seismic waves.

Answer 32

When seismic waves travel through weaker materials, they slow down and lose energy at a faster rate. This, in turn, causes wave amplitude to increase, creating a phenomenon known as ground amplification. Moreover, weaker materials can begin to vibrate at the same frequency as that of the seismic waves.

Question 33

Why is it that successful short-term earthquake prediction has so far been difficult to obtain.

Answer 33

This is likely because the processes that cause earthquakes occur deep beneath the surface and are difficult to monitor. And also, arthquakes in different regions or along different faults all behave differently, thus no consistent patterns have so far been recognized.

Question 34

Explain the relationship of the location of active volcanoes to their tectonic plate boundaries.

Answer 34

Most volcanoes derive their magma from subduction zones or from the upper mantle in what are referred to as hot spots. Hot spot volcanoes in an oceanic setting produce basaltic magma, and those on continents generate more rhyolitic magma. Depending on the tectonic setting, subduction zone volcanoes will erupt basaltic, andesitic, or rhyolitic magmas.