San tend to amplify and prolong the shaking. The

San Francisco is especially
susceptible to major damage by earthquakes due to massive construction on
established earthquake hazard zones with poor ground foundation. Beginning in
the Gold Rush of 1848, San Francisco experienced a massive population and land
expansion. The selling of underwater land, called “water lots,”
began in 1846, when the leaders of San Francisco desired to raise money for new
government and powerful landowners. To this day, many buildings continue to be built
on a foundation of landfill, thus posing the risk of liquefaction upon the
tremor. Liquefaction occurs when loose soil becomes saturated with water,
losing all fluidity and strength (Travis 1989). In these areas, younger Bay mud
creates a soft and malleable soil foundation. This mud, as compared to older
bottom mud, carries more moisture and becomes weak in the presence of pressure,
thus amplifying the motion of the ground (Travis 1989). Surprisingly, “the earthquake epicenter is NOT the
point at which most damage occurs…Thick, loose soils tend to amplify and
prolong the shaking. The worst such soils in the Bay Area are the loose clays
bordering the Bay – the
Bay mud” (Association
of Bay Area Governments 1998). Additionally, when the “water
lots” were purchased, the government
created a regulated requirement for the lot fill level. Many people did not
think twice before looking to the quickest and least expensive method to fill
them. This lead to modern day cities continuing to be built on a foundation made
of a mixture of sand, debris, and mud. “Even
now, remains of the Yerba Buena Cove vessels from 1851 are found under the
filled foundations of houses (BigThink 2015). Between 1849 and 1965, landfills
had intruded one third into the open area of the Bay (Travis 1989).

Approximately 2,300 acres of bay
surface “were being lost each year to landfills
for housing, ports, industry, airports, real estate, and dumps” (Travis 1989). Now, it has been shown that
infrastructure built on this land are slowly sinking, wobbling, and tilting due
to prolonged stress on the soft soil. In multiple areas, sand intrusions in
basements and ground floors of buildings have been reported (Seed 1991). However,
the competition for this area among construction industries persists, declaring
that it is the buyer’s responsibility for the upkeep of the
wobbly foundation. Much of this desire to continuously expand and build up the
outskirts of San Francisco began in 1906, following the catastrophic 1906
earthquake and fire which had caused severe damage to major areas of the city.
The hydraulic fill was placed to create new land to host the World Fair, bringing
in a large financial value, celebrating the successful rebuilding of the city,
and demonstrating to the rest of the world that the San Francisco had been
successfully resurrected (Seed et al 1991). It wasn’t until 1965 when California Legislature finally established
the BCDC, the first San Francisco Bay Conservation and Development Commission,
who was designed to halt the indiscriminate filling of the Bay (Travis 1989). However,
this new rule did not apply to the shoreline structures that were not part of
this “New Bay Fill Project.” Most importantly, shoreline landfill is the most
susceptible landfill area to damage during an earthquake. Additionally, no
rules were passed regarding correcting the previous inaccurate, careless
filling of these shoreline areas. Thus, these areas remain located in high-risk
danger zones, continuing to wobble on a foundation of loose soil.

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Not only does this unstable foundation
pose a direct risk to citizens, but also raises a concern for adequate transportation
in the case of an emergency. Buildings keep going up in landfilled areas, but
little attention is brought to the difficulty for fire trucks and emergency
vehicles to navigate through damaged streets and piles of rubble. The loose,
fine sand has created areas of “sand
boils, lateral spreading, settlement, partial bearing failures, structural
distress, pavement damage, and damage to pipes and other buried utilities” (Seed 1991). As demonstrated in
the major 1989 Loma Prieta Earthquake, a “number of buildings were destroyed or badly
damaged; much of the area was evacuated and public access was restricted
immediately following the earthquake’s initial impact” (Seed 1991). A lesson demonstrated
by the 1989 Loma Prieta Earthquake showed major damage to major routes of
transportation throughout the city that were built on landfill. This included damage
to the East Bayshore Highway (Interstate Hwy 80) and the “parallel coastal frontage road from
south Berkeley to the Bay Bridge” (Seed 1991). In other areas alongside major
highways, sand boils were observed on the sides of roads and cracked roads were
riddled with uprising sand, with fissures up to 300 feet long. This lead to the
Bay Bridge being completely shut down in the event of liquefaction. Other areas
showed damage in uneven railroad tracks and damaged pavements, making a number
of cranes unable to get through to certain areas. Additionally, major damage
occurred in San Francisco International Airport, Oakland International Airport,
and Alameda Naval Air Station, showing damage to runways, large sand boils, and
sand intrusion in certain terminal buildings. During a time of major crisis,
such as an earthquake, emergency air transport is a vital component for
emergency response teams. This past evidence shows potential damage and likely
loss of service due to their wobbly foundations, in which case would be an
absolute tragedy for the city.

barrier to earthquake emergency response teams is the increasing cost of real
estate in San Francisco, lessening the likelihood of emergency personnel to be
nearby and available on-demand. To demonstrate the rapid increase, according to
Trulia, market trends indicate an increase of $100,000 (9%) in median home sales
in the past year (Trulia 2017). Trends also show the average price per square
foot rose over $80, in the same time period (Trulia 2017). This skyrocketing greatly
prevents many public emergency personnel from living in the City or even in
close proximity. Many citizens are choosing to move across the bay to areas
such as Emervyille or Oakland where prices are slightly more stable. However,
as demonstrated in the last major quake, a powerful tremor could damage or completely
shut down the Bay Bridge, eliminating the quickest method for external
emergency personnel to reach affected areas of the densely populated city.


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