The incidences of landslides and earthquake in the areas around Washington Bay Area have been on the rise due to the nature of the rocks that make up the structures around these places. The torrential rains and the earthquakes have instilled fear among the residents from the regions within and around the weak fault line areas. It has, therefore, taken the interest of the risk analysts to create awareness on the looming risks that the residents around this place may encounter. Despite the fact that national standards for tracking landslide hazards are non-existent, ABAG has generated local maps that can assist a person to understand the possibility of risks in his/her location and know the best action to take to avoid the eventualities.
Major cities such as Alameda, Oakland, Berkeley and San Francisco have been identified as the most vigilant cities that have come up with efforts to facilitate awareness creation programs to enable the residents to beware of the possibilities of being victims of earthquakes and landslides and how to react in case they occur. These cities are noted to have joined hands in order to enhance resilience in the region because the Bay Area is associated with high case of landslides due to the nature of the land. The weak faults pose a great danger to the people and the knowledge that is being augmented through the joint programs of the cities mentioned above is highly regarded.
It is noteworthy that in as much as most buildings appear to be sturdy, they are at a risk of collapsing from incidences of earthquake because they lack adequate steel supporting bars that are capable of holding the pillars properly.
The faults around the Bay Area are associated with different levels of earthquakes. The San Francisco Bay Area is sliced by a series if faults that together allow the relative movement between the two plates; the Pacific Plate and the North American Plate. The faults that produce earthquakes around the Bay Area include Hayward, Calaveras, Concord-Green Valley, Greenville, Rodgers Creek, San Andreas, Mt. Diablo and the San Gregorio. The maps show simple lines to represent the faults, the level of complications associated with each is beyond word description. Notably, these faults are associated with varying capacities of earthquakes. There are some segments of faults that may experience long periods of earthquake while other experience short periods of earthquakes. Besides, in the event that a large earthquake occurs, small aftershocks are felt. For instance, after the 1989 Loma Prieta earthquake of 6.9 pitcher scale magnitude, some aftershocks manifested (Survey, 2013).
Earthquake hazard has been defined in the map as the extent to which the ground shaking due to earthquake is felt. It varies in probability. The hazards are shown to vary depending on the magnitude of the earthquake and the locations where earthquake is likely to be encountered. Also, the properties of the rock sediments through which the wave of an earthquake is propagated are known to determine the earthquake hazard level. Hazard maps have also been developed to show the distribution of the degree earthquake shaking. The distribution is gauged on the probability its occurrence within the United States. The information on these maps is very significant to the engineers and designers of infrastructure such as bridges, highways, buildings, highways and utilities that are capable of withstanding the shaking of earthquakes in the United States.
The level of damage of earthquakes are in most cases seen terms of how much they destroy buildings. It is noted that there are certain types of buildings that suffer greatly from earthquake due to their structure. It is admitted that certain buildings are very vulnerable and get extremely destroyed in the event that they are struck by earthquakes. Various aspects of ground failure such as liquefaction, landslides, and fault rapture and construction type are known to be the major determinants of how much earthquakes can damage buildings.Single Family House Over Garage is common type found in San Francisco especially in Richmond and Sunset district and also in East Bay regions. This house is characterized by a house attached over a garage. The garage does not have interior walls of the living space above it and is, therefore, not stable enough to withstand an earthquake. It is anticipated that ground shaking is likely to cause the garage to sway and collapse resulting into a damage to the living space. Nonetheless, a number of things can be done to improve the structure of this house type. For example, the walls of the garage can be reinforced by adding bracing elements or stiffening such as shear walls, steel frames, and cantilevered columns as advised by professional engineer.
Single Family Homes also known as Cripple Walls are also a common type that are vulnerable to earthquake shaking. When earthquake shaking occurs, the house is likely to slide off from its foundation and collapse. Inclusion of additional anchor bolts, sheathing along the portions and addition of plywood are the retrofit approach that is mostly used.
Soft-Story Wood Frame Multi-Unit Buildings are other buildings commonly faced with a high degree of damage during earthquake shaking. It is characterized by large openings on the first floor for parking or commercial space. Most of the buildings were constructed before 1990s.Ground shaking is likely to cause swaying of the building making the ground story to breakdown and eventually damage the upper floors. Bracing is the mostly done retrofit approach to improving the building structure.
Residents of California admit that they are very cautious when it comes to natural hazards such as the effects of scorching sun. However, they recognize the miss that pertains to the protection against earthquakes. The policy of home insurance in California does not extend to cover against earthquakes. They advocate for a separate insurance policy that provides a cover against earthquake damage. The California Residential Mitigation Program has launched a separate insurance policy that provides cover against the damage of the earthquake.
It is crystal clear that earthquake and ground shaking are very devastating and precarious. Different groups have advanced various plans for earthquake risk avoidance. According to the Red Cross Society, preparedness against earthquake is all about being armed with the proper supplies needed in times of emergency (Cross, 2012). They map out a plan that emphasizes on keeping the supplies in an easy-to-carry emergency preparedness kit. In the event that an earthquake occurs, it necessary to inform all the members of the family or schoolmates that an emergency has occurred. In order to remain safe, the American Red Cross advice a number of things to done. In the plan, begin by meeting together as a family or school to discuss how to prepare and respond to emergencies such earthquakes. Let everyone know their role in the event that an earthquake occurs. It is important to keep everyone aware on the level of safety during an earthquake.
In conclusion, it is noteworthy that weak faults are associated with landslides and earthquake that are very destructive and fatal. Everyone needs to beware of the looming dangers of earthquakes and ground shaking that likely to be experienced in different places. More categorically, earthquake prone areas such as Bay Area and San Francisco should be well understood by the residents. In addition, earthquake hazard should be known to engineers and designers to ensure that every structure they develop has a high capacity to withstand the waves of earthquakes.
References
ABAG. (2013, September 30). Do you know your landslide risk? Retrieved from The Earthquake and Hazards Program of the Association of Bay Area Governments: http://quake.abag.ca.gov/
Cross, A. R. (2012, June 2). Make a Disaster Preparedness Plan. Retrieved from http://www.redcross.org/prepare/location/home-family/plan
Survey, C. G. (2013, jULY). Seismic Hazard Zonation Program. Retrieved from http://www.conservation.ca.gov/cgs/shzp/Pages/Index.aspx
