SCI8_Q2_M2_Epicenter, Focus, Intensity, Magnitude of an Earthquake_ Active and Inactive Faults (1) 2

What is the point on the Earth's surface directly above the focus?

Epicenter.

Define focus in relation to earthquakes.

Focus (or hypocenter) is where the initial slip starts and is located beneath the surface of the earth.

What scale is most widely used to measure the intensity of an earthquake?

Modified Mercalli Scale.

What scale measures the strength or total energy of earthquakes?

Richter Scale.

What is the term for the energy released by an earthquake?

Magnitude.

What is the difference between magnitude and intensity of an earthquake?

Magnitude measures the energy released at the source; intensity measures shaking strength at a location.

How do scientists determine if a fault is active or inactive?

By assessing historical seismic activity or evidence of movement within the last 10,000 years.

What type of fault is likely to generate another earthquake in the future?

Active fault.

What term describes a fault that hasn’t shown signs of seismic activity in over 10,000 years?

Inactive fault.

What causes the violent shaking during an earthquake?

The sudden and rapid movement of a large volume of rock and the rupture along fractures in the Earth's crust.

What instrument is used to measure the magnitude of earthquakes?

Seismograph.

Define shallow-focus earthquakes.

Earthquakes that occur at depths less than 70 km from Earth's surface.

What percentage of earthquakes are classified as shallow-focus?

About 90%.

What are the two major components used to measure earthquakes?

Magnitude and intensity.

What is the Philippine Fault Zone?

The most extensive fault system in the Philippines, consisting of various fault segments.

Which fault line runs through Metro Manila?

West Valley Fault.

Identify one effect of earthquakes.

Tsunamis, loss of lives, destruction of properties.

What are the two primary ways earthquakes are measured?

Using the Richter Scale and the Modified Mercalli Scale.

What is the role of seismologists in studying earthquakes?

To identify and map seismic hazards and understand Earth's internal structures.

What is the importance of knowing the focus and epicenter of an earthquake?

It provides vital information for hazard assessment and resource allocation for rescue operations.

What did the Modified Mercalli Scale develop?

Twelve degrees of intensity identified by Roman Numerals.

The point where an earthquake starts is known as __________.

Focus.

The __________ is the location directly above the focus on Earth's surface.

Epicenter.

When measuring earthquakes, _________ looks at human experiences and damage.

Intensity.

In geological terms, a __________ is a rock fracture where blocks of rocks move relative to each other.

Fault.

The __________ is a graphical record of ground motion caused by seismic waves.

Seismogram.

What is the definition of intensity in the context of earthquakes?

The severity of shaking produced at a certain location.

The energy level of 7.6 on the Richter scale indicates what?

Magnitude.

Which fault is a dextral strike-slip fault running through Metro Manila?

West Valley Fault.

What type of earthquake has a focal depth greater than 300 km?

Deep-focus earthquake.

The __________ of an earthquake can help identify seismic hazards and emergency responses.

Focus.

What defines the difference between a shallow-focus and deep-focus earthquake?

Depth from the Earth's surface, with shallow being

How are seismic waves first detected?

Using a seismograph.

True or False: The intensity of an earthquake can be the same at different distances from the epicenter.

False; intensity varies by distance and local conditions.

Fill in the blank: The Modified Mercalli Scale is important for assessing __________.

Damage.

The area on the Earth where seismic waves are first felt is the __________.

Epicenter.

Which fault is located in the southern Mindanao region?

South of Mindanao Fault.

The __________ is a network of faults that contributes to seismic activity in the Philippines.

Philippine Fault Zone.

Name the scale used to measure how buildings and structures respond to shaking.

Modified Mercalli Scale.

Fill in the blank: A fault that has moved in the last 10,000 years is considered __________.

Active.

The __________ is the distance from the focus to the epicenter.

Focal depth.

What geological phenomenon causes the release of energy and subsequent shaking of the ground?

Earthquake.

Identify one preventive measure to take during an earthquake.

Drop, cover, and hold.

Fill in the blank: The Earth's crust is prone to __________ due to tectonic plate movements.

Earthquakes.