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Transcript of Earthquakes
Earthquakes can be caused by volcanic activity, these earthquakes are called Volcanic quakes.
When magma interacts with the rock, pressure is applied on the rocks which creates cracks. Every time the rocks crack a volcanic quake occurs.
Volcanic quake are usually very weak and can only be felt by seismographs.
1906 San Francisco Earthquake
The San Francisco earthquake caused about 24,671 wood builds to collapse and 3,168 brick building, in total 28,188 buildings collapsed in San Francisco. Most of the buildings were built with brick, stone and wood. 90% of San Francisco buildings made of wood which caused them to burn down with the fire and 54 of them were fireproof. Most of the city’s main buildings were built on the faults lines which is why lots of the main building and properties were damaged.
Impact on people and property
Due to the earthquake, 80% of the city was wrecked, 3000 people died, 200000 people were homeless out of a population of 400,000 and 28000 buildings burned down. It took San Francisco 4 years to recover from theses damages.
Pacific Ring of Fire
What is an earthquake?
An earthquake is the movement of the ground due to rocks under the earths surface.
How are earthquakes caused?
Earthquakes are known to be caused by the movement of tectonic plates and volcanic activity.
What impacts do earthquakes have?
Earthquakes have impact on the people, property, environment, and the economy of a country
The Ring of Fire is an area which borders the Pacific Ocean, this is where a lot of earthquakes and volcano eruptions occur. About 81% of the worlds largest earthquake happen in Pacific Ring of Fire.
Due to the earthquake, property damage was estimated $ 400 million and $235 million for insurance. The cost of the loss from the fire was $400,000,000 and the cost of damage for the earthquake was $80,000,000.
Tectonic plates are pieces of the earth crust which float above the outer mantle.
Tectonic plates are always moving but they move very slowly, so we can't feel the plates move. The plate boundaries sometimes meet and get stuck this creates pressure and when the energy is released it causes an earthquake.
The place where to plates grind against each other is called a "fault line".
How are earthquakes measured?
A common way earthquakes are measured is by the Richter Magnitude Scale, the scale rates earthquakes from 1-10.
Earthquakes are recorded through seismographs. These devices can detect earthquakes all over the world. Seismographs use electromagnetic sensors that convert ground motions, which then are processed and then recorded.
On April 18th 1906 around 5 AM, San Francisco faced a major earthquake. The magnitude was about 7.8. The earthquake lasted about a minute, but caused great damage. The quake was felt from Southern Oregon to Los Angeles. After shocks lasted about an hour and created fires. The fires lasted about three days and caused a massive amount of damage. Research showed that the San Andreas Fault was the cause of the earthquake.
The shifting rocks under the earth's surface cause shock waves. The shocks waves can be felt from thousands miles. There are two types of seismic waves, body waves and surface waves.Body waves travel below the earth surface. There are primary waves and secondary waves. Followed by primary and secondary waves are the Love and Rayleigh waves. Surface waves travel slower than body waves but are the most powerful.
1. What causes Earthquakes?
2. What are Tectonic Plates?
San Andreas Fault