Seismology and Earthquake Science

Seismology

• The study of earthquakes and the Earth's internal structure.

Seismologists

• Scientists who study earthquakes, their causes, and their impacts.

Seismograph

• An instrument that detects and records ground motion caused by earthquakes.

Seismograms

• Graphical representations of ground movements recorded by a seismograph.

Magnitude

• A measure of the energy released by an earthquake at its source (hypocenter).

Richter Scale

• A logarithmic scale used to express the magnitude of an earthquake.
• Developed in 1935 by Charles Richter.

Foreshocks

• Smaller earthquakes that occur before a larger, main earthquake.

Aftershocks

• Earthquakes that follow a larger main earthquake, often weaker but can cause additional damage.

Earthquake Hazards

• Ground shaking: Vertical and horizontal movements of the ground during an earthquake.
• Ground Rupture: The breaking or cracking of the Earth's surface along a fault line.

Before Earthquakes

• Learn about earthquake hazards in your specific location.

During Earthquakes

• Cover-Hold-Drop:
  • Cover: Seek shelter under a sturdy piece of furniture.
  • Hold: Hold onto the furniture to prevent being thrown around.
  • Drop: Drop to the ground to protect yourself from falling objects.

After Earthquakes

• Evacuate safely once the shaking stops, taking quick, safe routes.
• Monitor the situation for aftershocks using reliable sources.
• Check for injuries and provide assistance if required.

During Earthquakes: Additional Safety Tips

• Outside: Move to an open area away from buildings and overhead power lines.
• Near a Shore: Quickly move to higher ground to avoid tsunamis.
• Steep Slopes: Avoid locations with steep slopes, which are susceptible to landslides.
• Vehicles: Stop the vehicle if it's safe to do so, avoid driving if possible.

After Earthquakes: Additional Safety Tips

• Bridges & Overpasses: Avoid crossing bridges or overpasses, as they are prone to damage.

Seismology

• The scientific study of earthquakes and related phenomena.

Seismologists

• Scientists who study earthquakes, their causes, and their effects.

Seismograph

• An instrument that detects and records ground motion caused by earthquakes.

Seismograms

• Graphical representations of the ground motion recorded by a seismograph.

Magnitude

• A measure of the energy released by an earthquake at its source (hypocenter).

Richter Scale

• A logarithmic scale used to measure the magnitude of earthquakes.
• Developed in 1935 by Charles Richter.

Foreshocks

• Smaller earthquakes that occur before a larger, main earthquake.

Aftershocks

• Smaller earthquakes that follow a main earthquake, often lasting days, weeks, or even months.

Earthquake Hazards

• Ground Shaking: The vibration of the ground caused by seismic waves.
• Ground Rupture: The displacement of the Earth's surface along a fault line, causing cracks and fissures.

Before Earthquakes

• Familiarize yourself with potential earthquake hazards in your area.

During Earthquakes

• Drop, Cover, and Hold On: This is the recommended safety procedure:
  • Drop to the ground.
  • Cover your head and neck with your arms.
  • Hold on to a sturdy piece of furniture.

After Earthquakes

• Evacuate the area as soon as the shaking stops, taking the fastest safe route.
• Be prepared for aftershocks, which can cause further damage.
• Stay informed about the situation through electronic devices.
• Check yourself and others for injuries.

During Earthquakes (Specific Situations)

• Outside: Move to an open area away from buildings, trees, and power lines.
• Near a shore: Move quickly to higher ground to avoid tsunami threats.
• Near steep slopes: Move away from unstable areas prone to landslides.
• Inside a moving vehicle: Stop the vehicle in a safe location, away from overpasses, bridges, and other hazards.

After Earthquakes (Additional Considerations)

• Avoid crossing bridges or overpasses until they are inspected for damage.

Seismology

• The study of earthquakes.
• Branch of earth science.

Seismologists

• Scientists who study earthquakes and their hazards.

Seismograph

• Instrument used to detect and record ground motion.
• Provides data for seismograms.

Seismograms

• Graphical output of the seismograph
• Records seismic waves caused by earthquakes.

Earthquake Magnitude

• Measures the energy released from the earthquake's source (hypocenter).

Richter Scale

• Developed in 1935 by Charles Richter.
• Measures the magnitude of an earthquake.

Foreshocks

• Tremors that occur before the main earthquake
• Can be a warning sign.

Aftershocks

• Weaker earthquakes that follow the main earthquake.
• Can cause further damage.
• Can occur for days, weeks, or even months after the main earthquake.

Earthquake Hazards

• Ground Shaking: Movement and vibration of the ground surface.
• Ground Rupture: Breaking and displacement of the Earth's surface.

Before an Earthquake

• Familiarization with local earthquake hazards is vital.
• Prepare emergency kits and create evacuation plans.

During an Earthquake

• Follow the "Drop, Cover, and Hold On" safety protocol:
  • Drop to the ground.
  • Cover your head and neck with your arms.
  • Hold on to a sturdy object until the shaking stops.

After an Earthquake

• Check for injuries and provide first aid if necessary.
• Evacuate immediately to a safe location if possible.
• Stay informed about aftershocks and potential tsunami warnings.
• Be prepared to respond to potential damage and infrastructure disruptions.

Earthquake Safety Tips:

• If outside: Move to an open area away from buildings, trees, power lines, or other hazards.
• If near a shore: Move to higher ground immediately to avoid tsunami risks.
• If inside a moving vehicle: Stop in a safe, open area, away from trees, power lines, and overpasses.
• Never cross bridges or overpasses after an earthquake.
• Monitor emergency alerts and official channels for updates and safety guidance.

Volcano Related Hazards

• Eruption:
  • Pyroclastic Flow: Fast-moving currents of hot gas and volcanic debris.
  • Ballistic Projectile: Rocks and other material ejected from a volcano.
  • Volcanic Gas: Harmful gases released during eruption.
  • Lava Flow: Molten rock that flows from a volcano.

Lahar

• A destructive mixture of volcanic material, water, and rock.
• Flows rapidly, reaching speeds of 10 meters per second.
• Carries fresh volcanic material like pyroclastic flow and tephra.
• Can be triggered by volcanic eruptions, rainfall, or thunderstorms.
• Composed of volcanic debris.
• Gravity propels Lahars downhill, impacting the surrounding environment.

Ashfall

• A grey, dusty layer of fine volcanic particles.
• Ashfall: Volcanic particles less than 2 millimeters in diameter.
• Tephra: General term encompassing all volcanic fragments.
• Forms when volcanic particles are ejected into the air and fall back down.
• Health risks: Ash can be toxic when inhaled and contaminate water and soil.
• Biological hazards: Ash can cause skin problems and contaminate water supplies.

Volcano Related Hazards

• Eruption is the release of molten rock, ash, and gases from a volcano.
• Pyroclastic flow is a fast-moving current of hot gas and volcanic debris.
• Ballistic projectiles are rocks and other debris that are ejected from a volcano during an eruption.
• Volcanic gas is released during eruptions and can be toxic to humans.
• Lava flow is a stream of molten rock that flows from a volcano.

Lahar

• Lahar is an Indonesian word for a mudflow of volcanic debris and water.
• Lahars are a significant hazard, traveling at speeds up to 10 meters per second.
• Lahars can be triggered by volcanic eruptions, rainfall, or thunderstorms.
• Lahars are composed of volcanic material and can transport toxic chemicals.

Lahar Hazard

• Lahars can bury entire houses and cause significant damage.
• It is extremely difficult to survive being submerged in a lahar.
• Lahars are a significant threat to people and infrastructure.

Ashfall

• Ashfall is the deposition of volcanic ash from the atmosphere.
• Ashfall consists of volcanic particles less than 2 mm in diameter.
• Tephra is a general term for any volcanic material ejected from a volcano.
• Ashfall can contaminate water and soil making it dangerous for human health.
• Ashfall can cause respiratory problems and skin irritation.

Pyroclastic Flows

• Pyroclastic flows are a type of pyroclastic density current made up of volcanic particles, hot gases, and ashes.
• Pyroclastic flows are dense and move slower than pyroclastic surges. They are bound to the ground.
• Pyroclastic surges are diluted and have greater mobility.
• Pyroclastic flows can be dangerous because they are hot and fast-moving.
• Ballistic projectiles are formed from a volcano's eruption and are partially molten lava fragments.

Volcanic Gases

• Volcanic eruptions release various gases, including water vapor, carbon dioxide, sulfur dioxide, hydrogen sulfide, and hydrogen halides.
• Water vapor is colorless, odorless, and harmless.
• Carbon dioxide is colorless and odorless and can increase breathing difficulties.
• Sulfur dioxide is a colorless gas with a pungent odor that irritates the eyes, skin, and respiratory system.
• Hydrogen sulfide is a colorless, offensive gas with a rotten egg smell that can affect the respiratory system and cause unconsciousness.
• Hydrogen halides, including hydrogen chloride, hydrogen bromide, and hydrogen fluoride, are harmful to human beings.

Lava Flow

• Lava flows are streams of incandescent molten rock emitted from an eruptive vent.
• Lava flows are characterized by their bright red-orange appearance.