How vulnerable is Seattle?
Samhita Kasuganti
Sik5405@psu.edu
The Seattle Fault is a zone of multiple shallow east-west thrust faults that cross the Puget Sound Lowland and through Seattle (in the U.S. state of Washington) in the vicinity of Interstate Highway 90. The Seattle Fault was first recognized as a significant seismic hazard in 1992 when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about magnitude 7, an event that entered Indian oral legend. Extensive research has since shown the Seattle Fault to be part of a regional system of faults. Since Seattle is prone to earthquakes, it is important for the city to prepare for the disasters in order to reduce the damages. Below I have listed
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According to the maps, the North Western part of Seattle is has about 10-11 people per acre so the area is densely populated. This could be vulnerability for Seattle because high-elevated areas cause the maximum destruction. With an earthquake of magnitude 7.5, this area would cause the maximum deaths. We also see that west most part of Seattle is highly prone to landslides (according to the map Liquefaction Zones and Land Slide Prone Areas), but the overall land of Seattle is fairly elevated. Earthquakes are one of the main triggers that cause landslides. Earthquake induced landslides have been documented from as early as 372 BC (Keefer, 1984) and have caused tens of thousands of deaths and billions in economic losses (Keefer, 1984). Landslides have been a product of 40 of 56 documented earthquakes in present times around the world (Keefer, 1984). Topographic relief has an effect on the intensity of the waves propagating through the ground. Seismic waves are made of primary, secondary, and surface waves. Surface waves are the slowest type of wave but they cause landslides most often because they move particles in a swaying motion. Waves are amplified due to topography as seismic waves enter the base of a topographic ridge, are partially reflected back into the rock mass, and …show more content…
Soil liquefaction describes a phenomenon whereby a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid. The phenomenon is most often observed in saturated, loose (low density), sandy soils. This is because the loose sand has a tendency to compress when a load is applied; dense sands by contrast tend to expand in volume. If the soil is saturated by water, then water fills the gaps between soil grains. In response to the soil compressing, this water increases in pressure and attempts to flow out from the soil to zones of low pressure (usually upward towards the ground surface). However, if the loading is rapidly applied and large enough, or is repeated many times (e.g. earthquake shaking, storm wave loading) such that it does not flow out in time before the next cycle of load is applied, the water pressures may build to an extent where they exceed the contact stresses between the grains of soil that keep them in contact with each other. These contacts between grains are the means by which the weight from buildings and overlying soil layers are transferred from the ground surface to layers of soil or rock at greater depths. This loss of soil structure causes it to lose all of its strength. According to the
The Long Point Fault is located in Harris County, which covers 83,450 square miles located with in Houston, Teaxas City Limits. Research specifies that there are three sections of the Long Point fault that appear to be active; some sections of the Long Point fault have averaged more than 2 cm per year of vertical offset over the last 20 years. Evidence of the faults concludes it is a natural fault. The reason for activity is not caused by man, even though man’s activities are not helping the issues, but clearly humans are not the initial cause, biological activity can be in fact an adiitional cause for its movement. A brief description of the type of fault and its relationship with the strata and the faults beneath the Houston area, are at depths of 1,000 to 4,000 m. They have been well-defined through the study of well logs and seismic lines. Studies have resuted in assumuptions that some of these subsurface faults penetrate younger sediments at shallower depths, and contain faults that have of set the present land surface to produce recognizable scarps. (Gabrysh)
Imagine if a 9.0 earthquake struck the West Coast today, resulting in a giant tsunami. Coastal towns would be washed away or completely isolated, and electricity would be lost (FOX5). There would be $70 billion in damage and people would only have 15 minutest to evacuate or move to higher ground resulting in 10,000 deaths (FOX5). This sounds like a plot for a scary movie, but this is actually a reality. The Oregon Coast in located on a subduction zone, which makes it very susceptible to major earthquakes and tsunamis. With the Cascadia subduction zone running along he West Coast the threat of a major tsunami is very real.
Today, it's believed the first coins used and were bronze in West Valley City, around 20017. Coins were employed by Lydia in Asia Minor. The coins of the Lydian were termed "starters" that was a unit of weight. Entrepreneurs were placed having a lion's mind impression and made out of silver and gold metal. Nowadays, as you may think, the coins which can be still outstanding are very useful.
The Cascadia region has experienced several types of earthquakes and it is very likely to experienced similar quakes in the near future. Cascadia earthquakes fall into three major categories: The first type is shallow or crustal earthquakes which are caused by rupture of the faults in the North American Plate. The Scott Mills earthquake happened in 1993 and it occurred in the Willamette Valley. The second type is deep or intraplate earthquakes are caused by rupture faults within the subducting Juan de Fuca Plate, deep earthquakes are often the most damaging type of earthquakes. In 2001, a deep earthquake named the Nisqually hit the Puget Sound area of Western Washington. The third type is the Cascadia Subduction Zone earthquakes are the powerful and with the largest magnitude of 9 on the Richter scale. The Cascadia Subduction Zone is a bit more complicated than other two types of earthquakes. The zone separates the Juan de Fuca plates and the North American plate, subduction earthquakes happen when one plate is pushing beneath each other. When one of the faults ruptures, the overriding plate push upward generating frictional stress eventfully the stress reaches a critical point, a sudden failure occurs along the fault plane resulting in the “megathrust” earthquake rel...
Earthquakes in California are certainly not a surprise. What is a surprise is their unpredictability and randomness. Geologists say there is roughly a 50 percent chance that a magnitude 8 or more quake will hit the Los Angeles area sometime over the next 30 years. And, over the past twenty years, the Los Angeles area has witnessed several earthquakes, and in particular, two that were quite devastating; the 1971 San Fernando earthquake, and the January 17, 1994, Northridge Earthquake. Given the certainty that earthquakes will occur, they still seem to come as a surprise, and leave many communities unprepared to deal with their aftermath.
Gordon, Mary, and Cameron King jr. "Earthquake and Fire in San Francisco." University of California Press. 48.1 (1985): 69-79. Web. 5 Mar. 2014. .
benchmark for the future, and integrated investigation into the effects of earthquakes in the U.S.
The west coast of the islands is on the edge of a continental shelf created by ancient volcanic movement (Broadhead 5) .This volcanic activity is due to plate tectonic movement which also created the numerous amounts of earthquakes on the island. Compared to the rest of British Columbia, Haida Gwaii has the most earthquake activity (Broadhead 5), the last of which being in a magnitude of 7.7 on t...
Landslides are some of the most common and destructive natural hazards in Oregon. Annually, landslides cause millions of dollars of damage across the state. A number of factors, including climate, geology, and topography, make areas in and west of the Cascade Mountain Range particularly susceptible to this natural phenomenon. Additionally, expanding population growth has driven residential development onto steep slopes and other landslide-prone areas. Resultantly, an increasing emphasis has been placed on landslide research and mapping efforts.
The epicenter of the earthquake in Alaska was about 10km east of the College Fiord, approximately 90km west of Valdez and 120km east of Anchorage, Alaska largest city. The earthquake was felt about 1,300,000 square kilometers away from the epicenter. (Christensen, Doug PhD.) About 30 kilometers deep, the first slip occurred under northern Prince William Sound, and an 800 kilometer rupture in the rocks extended horizontally, roughly parallel to the Aleutian trench. (Bolt) The cause of this massive earthquake was the vertical displacement of northwest motion of the Pacific plate. Also, it was estimated that about 200,000 square kilometers of the crust were deformed, making this the greatest area of vertical displacement ever measured. (Bolt)
Quicksand, earthquakes, and wave loading are all examples of liquefaction. They all vary in intensity and the amount of liquefaction that occurs. Quicksand is created by water flowing upwards through sand. A flimsy cover of water coats each grain of the quicksand,
The earth is a very unique place with very intense catastrophes that occur throughout its lifespan. Some of these catalysts have the ability to completely alter the earth in ways that no man made invention could do. Earthquakes are among those catastrophes that cause unimaginable amounts of damage in what seems like no time at all. Earthquakes are caused by a collision of two plates in the earth. The collision will then send seismic waves across the surface of the earth destroying anything in its path. When earthquakes occur in the ocean, the collision can create a fault in the earth 's floor. The pressure from the seismic waves, combined with the shifting of plates will typically causes tsunamis as well.
The San Andreas fault line has causes constant development nightmares for large urban areas such as San Francisco and any other city that has been built on top of it. Fault lines are one of the side effects of the earth’s tectonic plates shifting that can result in devastating earthquakes. Some of the most devastating earthquakes in our modern era have occurred along the San Andreas fault line due to a dense population. The most notable earthquake on the San Andreas fault line occurred in San Francisco on 1906. The 1906 San Francisco earthquake was the most devastation of the earthquakes along the fault line due to its magnitude and the city’s ill preparedness. This earthquake and earthquakes to follow have been huge factors in how the city
Sometimes the movement is slow and steady, and at other time the plates are locked together, no able to discharge the compiled energy. When the compiled energy advances steady enough, the plates break free. Obviously and sadly, if there were no early warnings, if an earthquake occurs in a crowded and populated area, it may cause many deaths and injuries and a massive amount of property damage. It is clear to see that earthquakes are an ultimate uncontrollable and unpredictable hazard to life and property. As stated in the U.S Geological Survey, “Scientist have begun to estimate the locations and likelihoods of future damaging earthquakes. Sites of greatest hazard are being identified, and definite progress is being made in designing structures that will withstand the effects of
Earthquakes belong to the class of most disastrous natural hazards. They result in unexpected and tremendous earth movements. These movements results from dissemination of an enormous amount of intense energy in form of seismic waves which are detected by use of seismograms. The impact of earthquakes leaves behind several landmarks including: destruction of property, extensive disruption of services like sewer and water lines, loss of life, and causes instability in both economic and social components of the affected nation (Webcache 2).