Sismología y tectónica - 1ESO

New Section

This section introduces the topic of earthquakes, discussing their origins, measurement, and occurrence in specific zones.

Understanding Earthquakes

• An earthquake or seism is a sudden tremor of the Earth's surface resulting from the abrupt release of accumulated energy along an active fault.

• Active faults experience displacement, leading to earthquakes; for a fault to be considered active, it must have moved within the last 10,000 years.

• The theory of elastic rebound explains how stress buildup on active faults causes sudden energy release during an earthquake.

• The focus (hypocenter) is where the earthquake originates underground, while the epicenter is directly above on the Earth's surface.

New Section

This section delves into seismic waves generated by earthquakes and their characteristics.

Seismic Waves

• Seismic waves propagate outward from the hypocenter similar to ripples in water; they include internal waves for studying Earth's structure and surface waves causing most damage.

• Primary (P-waves) are faster longitudinal waves traveling through solids, liquids, and gases; Secondary (S-waves) are slower transverse waves only moving through solids.

• Surface waves include Love and Rayleigh waves that move perpendicular or elliptically to their transmission direction respectively.

New Section

This part discusses how seismographs record seismic activity and measure earthquake parameters.

Seismograph Functionality

• Seismographs detect seismic waves; sismograms depict wave patterns used to characterize earthquakes.

• Time intervals between P and S-wave arrivals help determine earthquake distance from seismograph; triangulation locates the hypocenter using data from three seismographs.

New Section

The section discusses the subjective nature of catastrophic events, the factors influencing their impact, and how magnitude is measured.

Catastrophic Events and Magnitude Measurement

• Catastrophic events are subjective and depend on reported sensations, population density, economic development, infrastructure characteristics, and distance from the epicenter.

• Magnitude measurement involves a simple calculation based on wave amplitudes (independent of distance) using the Richter scale.

• Theoretical magnitude values range from 0 to 10, with seismic activity concentrated in specific seismic zones due to active faults.