Topic 18 Flashcards
(22 cards)
THE STUDY OF EARTHQUAKE WAVES
SEISMOLOGY
FOCUSED ON THE MEASUREMENT OF SEISMIC WAVES USING INSTRUMENTS CALLED SEISMOMETERS (OR
SEISMOGRAPHS)
SEISMOMETRY
In what country and age attempts to determine the direction of earthquake waves originated
China 2000 BC
- First earthquake detection device
- Used pendulum to indicate
direction of tremors
Zhang Heng’s Seismoscope
(132AD)
17TH CENTURY -EARLY SCIENTIFIC SPECULATION
He did Theories on Earthquakes
Athanasius Kircher
- One of the deadliest earthquakes in European history.
- Marquis of Pombal’s scientific surveys on earthquake impact
1755 LISBON EARTHQUAKE
- Irish engineer and seismology pioneer.
- Coined the term “seismology” in 1846.
- Propose the concept of seismic waves.
ROBERT MALLET (1810- 1881)
2 Mallet’ Experiments
- Controlled Seismic Waves
- Seismic Intensity Mapping
- Beginnings of mechanical devices to detect earthquakes.
- Italian and British scientists’ early seismometers.
19TH Century
The first true seismograph, according to Italian seismologists, was created in 1875 by Italian physicist
Filippo Cecchi
Objects at rest tend to stay at rest, and
objects in motion tend to remain in motion, unless acted upon by an outside force.
Law of Inertia
Instruments That Record Earthquakes
seismographs or seismometers
waves of energy that travel through the Earth’s layers as a result of an earthquake,
volcanic activity, or other sources of sudden energy -release.
Seismic Waves
Types of Waves
-BODY WAVES
-SURFACE WAVES
Types of body waves that vibrations of particles are parallel to the direction of travel, Expansion and Compression
Primary Waves (P waves)
Types of body waves that vibrations of particles are perpendicular to the direction of travel
Secondary Waves (S waves)
Travel along the Earth’s surface and are slower than body waves, but they usually cause more damage due to their larger amplitude and the fact that they occur near the surface.
Surface Waves
There are two main types of surface waves:
-Waves Motion
-Side to side motion
- Rayleigh waves
- Love waves
Father of modern seismology
- Horizontal pendulum seismograph (1880s)
- Collaboration with James Alfred Ewing and Thomas Gray
John Milne (LATE 1800S)
- Development of more advanced seismometers
- Global networks of seismic observatories
1906 San Francisco Earthquake’s role in advancing the field
EARLY 20TH CENTURY – ADVANCEMENTS
IN SEISMOLOGY
- Charles F. Richter and Beno Gutenberg
- Development of the __________ Scale to measure earthquake magnitude
- Standardized earthquake quantification
Richter Scale- 1935
Development of the Richter Scale to measure earthquake magnitude
Charles F. Richter and Beno Gutenberg
