Earthquakes can devastate a city. They are a force of nature that can destroy any structure. The earth is made up of moving tectonic plates. Earthquakes occur along or near tectonic plate boundaries where two plates meet. These plates are solid rock and sit on the mantle which is a layer of molten rock. This molten rock is constantly moving in a convection current. The earth’s core is what generates the heat. The hotter rock rises away from the core and pushes up against the crust. Here it cools and then moves away on both sides. The now cooled rock sinks back to take the place of the hotter rock that has risen as shown in the diagram on the right. When the rock pushes against the crust it moves sideways. This moves the tectonic plates that are floating on top along with the molten rock.
When two different plates collide they can cause violent tremors called earthquakes. Most of these tremors are very minor and are happening all the time. They are so small that we can’t feel them. Plates can also slide past each other which can cause very minor micro quakes. The plates are slipping about 10 millimetres a year, about the rate of fingernails. When plates aren’t slipping enough it can cause major problems. When plates aren’t slipping enough it shows that something is preventing the plates from sliding. When enough pressure builds up it will restart the sliding with a jolt. When this happens it causes major damage to any cities or towns near the epicentre. The epicentre is directly above where the movements began. Where the movements begin is called the focus. The devastation of a city depends on the size of the quake and the location of the epicentre.
On April the 18th in 1906 one of the most devastating earthquakes in history struck San Francisco in California, America. Along with subsequent firs the earthquake destroyed the city and making it the worst disaster to hit a North American city.
San Francisco is on the west coast of the United States of America. The western coast of America has a huge fault line running up the side of it. The San Andreas Fault runs along the coast of California and joins the North American and Pacific plates. As shown in the diagram on the right, the fault runs straight through San Francisco and right along the coast. When the two plates slide along they create huge quakes that shake the ground. There have been many earthquakes generated from this fault line but the worst one was in 1906.
At 5:12 am on the 18th of April 1906 in San Francisco the foreshock hit the slumbering city. The force of the earthquake was so great that the tremors were felt right throughout the San Francisco and it reached as far inland as Nevada (500km away). Along the San Andreas fault the plate slipped up to 21 feet. 20 seconds after the initial foreshock the main earthquake hit, lasting for about 1 minute. Although it lasted for merely a minute it wrecked mass destruction. After the quake people walked the streets confused. Some people had no idea how much damage had been done. Some people walked to work as per usual only to find the buildings on a lean or fallen. Not only was there structural damage to the city but there was a significant loss of life. Many people were trapped under building and cries of help could be heard coming from the piles of rubble. Those that survived could not be taken to the hospitals as they had sustained major damage. The injured were taken to the dance hall.
What no one realised that the worst was yet to come. The greatest tragedy had not yet unfolded. The earthquake had severed gas mains and toppled chimneys. 60 different fires broke out following the quake. The fires that followed the quake were what truly destroyed the city.
The San Francisco Fire Department was thought to be “invincible” however the fires were so uncontrollable that they burned for 3 days, reducing the city to smoking rubble. The streets were lined with wooden structures and tightly packed market stalls that went up in flames very easily. Only a few buildings were made of bricks and steel like some hotels and banks. This is why some say that San Francisco was a city waiting to burn. These big hotels came crashing down when the quake hit anyway.
The individual fire brigades went straight to work without the telephones to communicate, but they all knew exactly what to do, put out the fires. When they arrived on the scene there was no water. The quake had broken almost all of the water lines coming into the city. Fire hydrants let out a useless trickle before going dry, doing nothing to help the 12 out of control fires. By 8:00 am more than 1700 troops had gathered in San Francisco to fight fires, evacuate the people and prevent crimes. In the chaos that followed the soldiers themselves were caught looting.
At around 9:00 am in an area of the town that had not been hit as badly, one lady started a fire in her fireplace to cook her breakfast, oblivious to the fact that the quake had damaged their chimney and blocked it off. The result was devastating. By 12 noon the “ham and eggs” fire, as it came to be known, was on its way to claiming a good part of the city. The pictures on the right are those of the ham and eggs fire.
It was said that some of the more modern buildings would be able to withstand the flames, most prominent the call building. This was one of America’s first sky-scrapers. It burned from the top down, the elevator shafts provided oxygen to flames.
Towards the afternoon, the fires could be described as a firestorm. It generated its own super-heated wind. The fire had cut the city off from the outside world. Not only did they have no communications on the outside, all communications on the inside were destroyed too.
By nightfall soldiers and officers had evacuated thousands of people. Unfortunately the soldiers in a rush would not let anyone take their possessions with them. There were numerous reports of shootings and looters were to be killed immediately. Children caught looting were spared but were publically humiliated with a big sign put on them.
By 10:00pm the city had surrendered. There was nothing to do but watch. South of market was gone, the financial district was gone and china town would go in the night. In the morning the residents were dumbfounded. Possessions, homes and their whole lives had been destroyed. There were ferries taking people across the bay. Smoke was everywhere and there was a great silence over the city.
By mid-day on April 19th, 250,000 were homeless and over 3,000 were dead. This was only the beginning and the city would burn for another two days. The costs were substantial. $235 – $500 million dollars which in today’s money would be about $4.8 – $10 billion dollars.However there were some positives to come from it
Positives?
