Understanding Earthquakes and Their Effects

Earthquakes

• The buildup of stress in the Earth's crust, primarily caused by the movement of tectonic plates, leads to earthquakes.
• Earthquakes are typically most intense at convergent plate boundaries, where plates collide.
• The point within the Earth where an earthquake originates is called the focus or hypocenter.
• Volcanoes are often located at convergent plate boundaries where subduction occurs, and at hotspots, which are areas of volcanic activity unrelated to plate boundaries.
• When accumulated stress in rocks exceeds their strength, the rocks rupture causing an earthquake.
• Subduction zones at convergent boundaries are associated with the formation of deep ocean trenches, volcanic arcs, and earthquakes.
• The epicenter of an earthquake is the point on the Earth's surface directly above the focus.
• A hotspot is an area of volcanic activity caused by a plume of hot mantle material rising to the surface.
• Seismographs are instruments used to detect and record seismic waves generated by earthquakes.
• P-waves (primary waves) arrive first at a seismograph station during an earthquake.
• The epicenter of an earthquake is determined using the time difference between the arrival of P-waves and S-waves at multiple seismograph stations.
• S-waves (secondary waves) can only travel through solids.
• Surface waves are characterized by causing the most damage during an earthquake.
• The difference in arrival times of P-waves and S-waves at a seismograph station is used to determine the distance to the earthquake's epicenter.
• Love waves are not a type of seismic wave produced by earthquakes.
• Understanding the focus of an earthquake is crucial because it provides information about the earthquake's depth, which affects ground motion and damage.

Nervous System

• Sensory organs are responsible for detecting stimuli from the environment and transmitting them to the brain.
• Photoreceptor cells in the eye are responsible for detecting light.
• The neuromuscular junction is the site where a motor neuron communicates with a muscle fiber.
• Mechanoreceptor cells respond to touch and sound.
• Interneurons in a reflex arc connect sensory neurons to motor neurons.
• The primary purpose of a reflex reaction is to provide a rapid response to a stimulus, often for protection.
• The cerebral cortex is responsible for higher cognitive functions like thought and memory.
• Neurotransmitters can stimulate hormone secretion into the bloodstream.

Sound

• Sound travels slowest in gases because the particles are farther apart and collide less frequently.
• Humans typically hear sound in the frequency range of 20 Hz to 20,000 Hz.
• Hard, smooth surfaces reflect sound waves, which can lead to echoes.
• Sonar technology uses echoes to measure distance by emitting sound waves and timing the return of the echoes.
• The eardrum vibrates in response to sound waves, transmitting the vibrations to the middle ear.
• Frequency determines the pitch of a sound wave: higher frequency means higher pitch.
• Soft, porous materials are best at absorbing sound waves.
• The human ear consists of the outer ear, middle ear, and inner ear.
• Amplitude in a wave indicates the intensity or loudness of sound.
• Frequency is measured in Hertz (Hz), which represents the number of cycles per second.
• Wave speed is related to frequency and wavelength: speed = frequency x wavelength.
• Radio waves have the longest wavelength in the electromagnetic spectrum.
• Electromagnetic waves can travel through a vacuum.
• As the frequency of a wave increases, the wavelength decreases.
• The approximate speed of electromagnetic waves in a vacuum is 3 x 10^8 m/s.
• Sound is not part of the electromagnetic spectrum.