It was in the early morning of February 9, 1971, that the San Fernando earthquake erupted in the San Gabriel Mountains foothills in Southern California. The earthquake, also known as the Sylmar Earthquake, was an unanticipated thrust quake that shook California. It had a magnitude of about 6.5 to 6.7 and the intensity of the quake was said to be Mercalli Intensity of XI, which is considered to be an extreme one. It was one of the kind earthquakes that caused havoc to the northern San Fernando Valley and the neighboring areas.
The impact of the Sylmar earthquake was that it created a San Fernando fault zone that falls between the San Gabriel Mountains and San Fernando Valley. The result of the tectonic ruptures in the faulty zone meant that several properties were damaged due to the quake. The surface faulting extended up to 15 kilometers and the lateral offset was measured at 1-meter maximum. The total surface damage of this earthquake was found to be about 12 miles or 19 kilometers long. The maximum slip that happened due to this Sylmar earthquake was up to 6 feet or 2 meters.
The urban settings along this area were totally damaged with city streets and neighborhoods bearing the brunt of the earthquake. The businesses and the private homes in the vicinity of the epicenter had to face severe damages. The major damaged seen was at the Olive View and the Veterans Administration Hospitals. The freeway overpasses also collapsed due to the earthquake. The earthquake resistant buildings built at the Oliver View Hospital also were not spared and four, five story buildings were pulled down from the main hospital building during the earthquake. The lives of 49 people were accounted for in the Veterans Administration Hospital in San Fernando. This was mainly due to the collapse of the old building at the venue. Most of the older buildings in Beverly Hills, Glendale, Alhambra and Burbank were not able to bear the brunt of the severe earthquake and collapsed.
The Sylmar Earthquake was a severe one as it caused over $500 million of damage to property and land. It also accounted for the lives of 65 people. This day was a sad day in the history of California that frequently has to carry the brunt of Nature’s fury. The other main damage was to the newly constructed freeway. Many of the experts feel that the damage caused by the severe Sylmar earthquake was more or less similar to the 1994 Northridge Earthquake that shook California altogether. It was only because the earthquake happened very early in the morning that there were not many losses of life.
One of the biggest earthquakes to rock San Francisco was the San Francisco earthquake of 1906. It was called as the Great Quake of 1906. The epicenter of this devastating quake was about 2 miles south of San Francisco City. The earthquake was felt at 5:12 am on April 18, 1906, and it struck the Northern California coast. The earthquake was recorded to be having an intensity of 7.8 on the Richter scale. It was also said to be a very severe and extreme one that had a depth of 5 miles. There was a strong foreshock of about 20 to 25 seconds before the attack of the quake. The main shock lasted for about 42 seconds.
There was severe shaking felt from Eureka to Salinas Valley. This means that the stretch from the North to the South of San Francisco Bay felt the effects of the Great Quake of 1906. The effect of the severe earthquake was severely felt in the city as the fire broke out in the city and it lasted for several days. The fire had a devastating effect on the city and caused a lot of damage to the city. It was reported that nearly 80% of San Francisco city was damaged and it took a lot of time and money to repair the damages caused by the earthquake. The fire and the earthquake were recorded to be one of the worst damaged to hit the California State.
It was found out that the shaking intensity of the earthquake was correlated to the core geological conditions. The stronger shakings were felt in the areas that were located in the sediment filled valleys and the bedrocks sites did not face a major shake like the sediment areas. The entire downtown of Santa Rosa was destroyed.
It was estimated that as many as 3,000 people had lost their lives due to the Great Quake of 1906. My good friend who works at http://www.asbestosremovalanddemovancouver.com had a grandfather pass away in this earthquake. As many as 200,000 people had lost their homes in this nature’s fury and were left homeless. They had to camp in the city parks under the tents supplied by the Army. The other refugee camps were located in the Presidio and the Panhandle areas and along the beaches between the Ingleside and the North Beach. Even after two years of the quake, many of the refugee camps were still in function. This was the extent of damage that the Great Quake caused in California.
California and nearby areas are witnessing a series of seismic activity for the past one week. An earthquake of the magnitude 4.6 happened in Gold Beach in Oregon in August. Another earthquake of magnitude 3.4 shook the Running Springs area at UTC time Monday, August 14, 2017, at 11:11 AM. The epicenter was at a depth of 6km. Many people in the area have reported of experiencing the mild tremor. Areas like Southern California, Greater Los Angeles, San Pedro Channel and Santa Monica Bay experienced the vibrations. The tremors are continuing. California has experienced 29 earthquakes of magnitude 1.5 or greater in 24 hours from 13th August to 14th August.In the past seven days; the area has experienced more than 211 earthquakes. More than 900 quakes have been reported in the past 30-day period from the different areas of the state. It includes Gold Beach, Ferndale, Running springs, Bridge Port, Mammoth lakes, Ridgemark, Borrego, Anza, etc.
Largest quake of 2017
The largest quake in California of this year was experienced in Ferndale. This earthquake happened 8 months ago was about 6.5 magnitudes and the epicenter was at a depth of 12km. Ferndale which has a population of 1300 people felt the tremble for about 15 seconds. Though no major damages or injuries were reported during these series of earthquakes in California recently, scientists are warning of a major shake that may cause great devastation in the Southern California area.
Why is California experiencing a series of tremors?
The seismological position of California is the cause of continuous seismic activity. California falls in the most active and dangerous tectonic area. California lies in Pacific tectonic plate partly and partly on the North American plate. When these plates come in contact it can cause devastating earthquakes. When the plates are moving in different directions, the earthquakes will be harmless. The earthquake felt by people differ depending on the magnitude of the quake, the distance from the epicenter and the soil conditions of the area. The earthquake at Loma Prieta on 17th October 1989 was one of the most damaging earthquakes in the recent history of California. It killed 63 people.
This was an earthquake of major proportions that came on in Northern California on 17th October 1989 which caused extensive damage across a wide region. This quake was recorded in the world series of earthquakes as the quake of 89. There were about 60 deaths that happened and 400 injuries recorded. The Loma Prieta earthquake was capable of causing much more damage, but for the retrofitting, that had taken place in the Bay Area and other regions from before.
As per the findings of the scientific community this earthquake was due to certain magnetic disturbances that occurred around fault areas which happened two weeks before the quake took place. The occurrence was on 17th October 1989 around 5.04 PM which registered 7.1 on the Richter scale. The epicenter of the quake was in the Santa Cruz mountain area of the Loma Prieta peak, which occurred along the San Andreas Fault line. This fault line is a boundary that exists between the North American and Pacific tectonic plates. As a result of the impact, rocks were dislodged which fell from a height of seven feet when the quake occurred.
At such a time the Bay Area had a lot of people excited over a game that was taking place between the San Francisco Giants and Oakland A’s which were local teams. At the time when the warm ups were taking place the quake occurred. That led too much of the quake footage captured on news cameras. This event was extensively covered by news footage as a result, one of the first earthquakes in media history.
Among the recognizable damage that occurred due to the quake is the dismantling of the Bay Bridge which connects Oakland to San Francisco. The upper deck of this double decked structure collapsed, which trapped people who were traversing on both sides of the bridge. There were signs of devastation in other regions of the Bay Area as well, such as Interstate 880 where a freeway of two levels fell apart and killed 42 people. Santa Cruz area saw the collapse of the Pacific Garden Mall, buildings, towers, and malls. Though the damages were extensive, due to earthquake retrofitting many areas were saved from more damages that could have occurred.