Earthquakes: The 1906 San Francisco Earthquake

The 1906 San Francisco Earthquake

Many scientists consider the “Great Quake” of 1906 as one of the most important in history. But why?

It is not the largest earthquake ever or the most destructive one. The San Francisco earthquake, however, had long-lasting effects other than the collapse of buildings.

It changed the way Californians live their lives and changed the way scientists think about earthquakes.

How did it affect everyday people?

After much research, it became clear to scientists that the 700 reported deaths from the San Francisco earthquake were avoidable.

The earthquake itself was not what caused most of this destruction.

The large majority of these deaths happened because buildings were made very badly or they had been built on unstable soil.

This affected poor people the most because they lived in the parts of town where the worst buildings were made.

Because of the unnecessary destruction, laws have been passed requiring buildings to be more earthquake-safe.

This has lowered the number of deaths in later earthquakes and kept Californians safer.

How did it affect scientists?

Much of what we will learn about earthquakes is based on what happened in the 1906 earthquake.

It helped scientists realize that earthquakes don’t create faults – they happen along faults.

They also noticed that earthquakes happen after long periods when the Earth’s crust is under pressure. After many years of the pushing, pulling, and sliding because of plate movements, the crust suddenly slips and causes an earthquake.

Scientists discovered all of this information, and the theory of plate tectonics was not even formed yet.

But when the time finally came to connect earthquakes to the movement of the tectonic plates, the 1906 San Francisco earthquake played an extremely important role.



Volcanoes: Lassen Peak & Plate Tectonics

Volcanoes: Lassen Peak

Lassen Peak and Mount Shasta are both volcanoes that are part of the Cascade mountain range, which runs across Northern California, Oregon, and Washington.

Like many other volcanoes, Lassen Peak formed along a convergent plate boundary between an oceanic and a continental plate.

In the case of Lassen Peak, it is the North American plate and the Pacific Plate that are colliding. Because the North American plate is a continental plate and the Pacific Plate is an oceanic plate, this has formed a subduction zone.

Here the Pacific Plate sinks below the North American plate and then part of it melts. The hot melted rock (magma) then rises through the top layers of the Earth, and forms a volcano.

That’s how plate tectonics helped to form Lassen Peak, and the 30 other volcanoes found in Lassen Volcanic National Park!

Volcanoes: Mammoth Mountain & Long Valley Caldera

Volcanoes: Mammoth Mountain &

Long Valley Caldera

Both Mammoth Mountain and Long Valley Caldera are located in Eastern California, very close to the Nevada border. It takes about 6 hours to get from the San Fernando Valley to Mammoth Mountain.

Mammoth, in particular, lies near the Sierra Nevada mountain range – towering and beautiful peaks that are the leftover pieces from huge, ancient volcanoes which used to exist here.

The closeness of Mammoth Mountain and the Long Valley Caldera to the Sierra Nevada has given scientists possible clues to solve the tectonic mystery of how these volcanoes formed.

Some scientists believe that millions of years ago the plate boundary between the North American plate and the Pacific Ocean used to be much farther east than it currently is.
 
This means that California did not exist! And the coast of the Pacific Ocean instead was located on the California-Nevada border – right near where the Sierra Nevada is currently found.

The border between Nevada and the Pacific Ocean formed a convergent plate boundary, where the two plates are coming together or colliding.

There, a subduction zone formed between the North American plate and the Farallon plate (which doesn’t exist anymore).

This zone formed the Sierra Nevada range, and scientists believe that this could also be the mysterious cause of the Mammoth mountain volcano and the Long Valley Caldera.

Volcanoes: Mount Shasta

Volcanoes: Mount Shasta

Mount Shasta provides beautiful views to the small mountain communities that surround it. But the possibility of an eruption has these villages preparing for the worst.
 
Mount Shasta is the second highest volcano in the United States, and one of the tallest peaks in the Cascade Range. Though there is just one mountain, it is actually made up of a handful of volcanic vents (where lava could someday erupt from).
 
It is a relatively young volcano. But it was actually formed on earlier volcanic mountains that have been erupting in this area for the last 600,000 years.
 
According to geologists, there is a one in four or one in three chance that Mount Shasta could erupt in our lifetimes.
 
Even now, the mountain experiences constant volcanic activity – though it is not strong enough for most people to notice.
 
The most recent eruption occurred about 200 years ago – and it was so large that it caused a huge tsunami in Japan, several thousand miles away.
 
Despite the chance that the volcano could erupt, Mount Shasta remains a popular tourist destination.