ST: Earthquakes and Faults

• What is an earthquake?

  An earthquake is an intense shaking of Earth's surface.
• What causes the shaking during an earthquake?

  The shaking is caused by movements in Earth's outermost layer.
• What are the four types of earthquakes?

  • Volcanic Earthquake
  • Tectonic Earthquake
  • Explosion Earthquake
  • Collapse Earthquake
• What is a volcanic earthquake?

  A volcanic earthquake results from tectonic forces occurring with volcanic activity.
• What is a tectonic earthquake?

  A tectonic earthquake occurs when the earth's crust breaks due to geological forces on rocks and adjoining plates.
• What is an explosion earthquake?

  An explosion earthquake results from the detonation of a nuclear and/or chemical device.
• What is a collapse earthquake?

  A collapse earthquake is a small earthquake in underground caverns and mines caused by seismic waves from surface explosions.
• What is the intensity of an earthquake?

  The intensity of an earthquake is a number written as a Roman numeral.
• What does the intensity of an earthquake describe?

  It describes the severity of an earthquake in terms of its effects on the earth's surface and on humans and their structures.
• Who developed the Modified Mercalli Intensity Scale?

  Harry Wood and Frank Neumann developed the Modified Mercalli Intensity Scale in 1931.
• What is magnitude in the context of earthquakes?

  Magnitude refers to the measurement of the energy released during an earthquake.
• Who created the Richter scale?

  Charles Richter created the Richter scale in 1935.
• What is the San Andreas Fault?

  The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometers through California.
• What is a fault?

  A fault is a fracture or zone of fractures between two blocks of rock.
• What is the difference between intensity and magnitude of an earthquake?

  Intensity measures the effects of an earthquake, while magnitude measures the energy released.
• What is the New Madrid Fault Line?

  The New Madrid Fault Line is located in the New Madrid Seismic Zone at coordinates 36.5830° N, 89.5877° W.
• What are some famous fault lines?

  • San Andreas Fault
  • New Madrid Fault Line
  • Pacific Plate
  • Nazca Plate
  • Scotia Plate
  • Cocos Plate
  • Caribbean Plate
  • Philippine Plate
  • Fiji Plate
• What is an active fault?

  An active fault is likely to have another earthquake sometime in the future.
• What is an inactive fault?

  An inactive fault is a structure that does not have earthquakes.
• What is the Philippine Mobile Belt?

  The Philippine Mobile Belt is a tectonic region where all faults in the Philippines are inter-related.
• How is the Philippine Mobile Belt compressed?

  It is compressed on the west by the Eurasian Plate and two arms of the Sunda Plate, and on the east by the Philippine Sea Plate.
• What are terranes in the context of the Philippine Mobile Belt?

  Terranes are long and narrow blocks like the Zambales ophiolites, which are at least 400 km long and 50 km wide.
• What is the Philippine Fault System?

  The Philippine Fault System is a major inter-related system of geological faults throughout the Philippine Archipelago.
• What is the threat posed by the Marikina Valley Fault?

  The Marikina Valley Fault is almost fully locked, accumulating elastic strain at a rate of 10 to 12 mm/yr.
• What is the estimated magnitude of an earthquake from the Marikina Valley Fault?

  The estimated magnitude is between 6–7 and as high as 7.6.
• What is the predicted death toll from an earthquake caused by the Marikina Valley Fault?

  The predicted death toll could be as high as 35,000.
• How many buildings are endangered by the Marikina Valley Fault?

  6,331 buildings are endangered in a span of 2,964.10 square kilometers.
• What is the Western Philippine Fault also known as?

  The Western Philippine Fault is also known as the West Philippine Fault.
• Where is the Western Philippine Fault located?

  The Western Philippine Fault is located in the National Capital Region.
• When did the last slip of the Marikina/West Valley Fault System occur?

  The last slip occurred in 1771 AD.
• What is the significance of the water level concerning the West Valley Fault Line?

  The West Valley Fault Line runs through the seas of the Western region of the Philippines.
• What is the Eastern Philippine Fault?

  The Eastern Philippine Fault is an active fault found in the Philippine Sea.
• What caused the Guinsaugon earthquake?

  The Guinsaugon earthquake was caused by a rupture in the Central Philippine Fault Zone.
• What is the Central Philippine Fault responsible for?

  The Central Philippine Fault is responsible for fault creep, slow slide occurrences, and large earthquakes.
• Where does the Southern Mindanao Fault run?

  The Southern Mindanao Fault runs across the Celebes Sea and the Moro Gulf.
• Why is it important to know if faults are present in an area?

  • To predict where earthquakes are likely to occur
  • To understand the risk of earthquake hazards in different areas