| Earthquake Awareness and Preparedness |
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| Figure 2 - Earthquake Damage to Homes |
| Figure 3 Effect of Earthquake Magnitude |
| Figure 4 Effect of Distance from Fault Line |
| Figure 1 - USGS Earthquake Map USGS permission, Dr. E. Schweig |
| Figure 5 Effect of Soil Amplification |
| Photo 1 - Soil Liquefaction and Sand Blows |
| Photo 2 - Liquefaction and Ground Settlement |
| Photo 3 - Fire Hazard destroying a Steel Building |
Natural Hazards due to Earthquakes Affecting Home Safety
Earthquakes are often associated with natural hazards that affect your home safety or life safety. Natural
hazards during or following an earthquake include soil amplification, liquefaction, landslides, surface fault
rupture, tsunamis, fire hazards, industrial hazardous materials release, and chemical hazards release
from garage or utility room.
Earthquakes are often associated with natural hazards that affect your home safety or life safety. Natural
hazards during or following an earthquake include soil amplification, liquefaction, landslides, surface fault
rupture, tsunamis, fire hazards, industrial hazardous materials release, and chemical hazards release
from garage or utility room.
Soil Amplification
The depth and the types of soil materials from the ground surface to the base rock affect the nature of the
surface ground shaking. For instance, deep soils in sedimentary basins would shake more than bedrock
in the hills as a result of persistent shaking where seismic waves are trapped and reverberate. In addition,
soft soil deposits filter short period vibrations and amplify long period shaking, thus increasing the
likelihood of earthquake damage to long-period structures such as high-rise buildings and long-span
bridges.
The depth and the types of soil materials from the ground surface to the base rock affect the nature of the
surface ground shaking. For instance, deep soils in sedimentary basins would shake more than bedrock
in the hills as a result of persistent shaking where seismic waves are trapped and reverberate. In addition,
soft soil deposits filter short period vibrations and amplify long period shaking, thus increasing the
likelihood of earthquake damage to long-period structures such as high-rise buildings and long-span
bridges.
Liquefaction
Liquefaction occurs during strong back-and-forth ground shaking in areas where high ground water table
exists in loose sandy soils or poorly-compacted artificial fill. Partially saturated soil deposits may
completely lose cohesion during prolonged ground shaking, behave like a liquid, and lose their ability to
support the concrete foundations of the building. Liquefaction results in permanent ground deformations
such as lateral spreading and settlement, both of which increase the likelihood of damage to buildings
and infrastructure. Areas prone to liquefaction in California include San Francisco Bay Area, Northwestern
Alameda County, Northern Santa Clara Valley, Southern Coachella Valley, and Upper Santa Ana River
Basin. If you live in California, check the USGS earthquake map for liquefaction susceptibility at
http://earthquake.usgs.gov/regional/nca/qmap/. Soil liquefaction also occurs in the Midwest within the
Central Mississippi River Valley (including the Reelfoot Scarp, the New Madrid Seismic Zone and the
Western Lowlands) and the Mississippi and Ohio Rivers Regions (including the Wabash Valley and St.
Louis-Cape Girardeau). If you live in the Midwest, check the USGS earthquake map for liquefaction features
at http://earthquake.usgs.gov/hazards/qfaults/usmap.php. The earthquake pictures illustrate the permanent
ground settlement due to liquefaction along the perimeter of Port Island (artificial fill) during the 1995 Kobe
Earthquake. All the streets of Port Island away from the shore were covered with a layer of
partially-saturated sand that had liquefied and came out to the surface thru sand blows (photo 1), while the
shore line moved 6 to 9 ft outward into the sea and settled as much as 3 ft (photo 2).
Liquefaction occurs during strong back-and-forth ground shaking in areas where high ground water table
exists in loose sandy soils or poorly-compacted artificial fill. Partially saturated soil deposits may
completely lose cohesion during prolonged ground shaking, behave like a liquid, and lose their ability to
support the concrete foundations of the building. Liquefaction results in permanent ground deformations
such as lateral spreading and settlement, both of which increase the likelihood of damage to buildings
and infrastructure. Areas prone to liquefaction in California include San Francisco Bay Area, Northwestern
Alameda County, Northern Santa Clara Valley, Southern Coachella Valley, and Upper Santa Ana River
Basin. If you live in California, check the USGS earthquake map for liquefaction susceptibility at
http://earthquake.usgs.gov/regional/nca/qmap/. Soil liquefaction also occurs in the Midwest within the
Central Mississippi River Valley (including the Reelfoot Scarp, the New Madrid Seismic Zone and the
Western Lowlands) and the Mississippi and Ohio Rivers Regions (including the Wabash Valley and St.
Louis-Cape Girardeau). If you live in the Midwest, check the USGS earthquake map for liquefaction features
at http://earthquake.usgs.gov/hazards/qfaults/usmap.php. The earthquake pictures illustrate the permanent
ground settlement due to liquefaction along the perimeter of Port Island (artificial fill) during the 1995 Kobe
Earthquake. All the streets of Port Island away from the shore were covered with a layer of
partially-saturated sand that had liquefied and came out to the surface thru sand blows (photo 1), while the
shore line moved 6 to 9 ft outward into the sea and settled as much as 3 ft (photo 2).
Landslides
Landslides may occur during an earthquake for steep sloping areas underlain by loose or soft
rock, like the Eastern San Gabriel Mountains in California that will cause damage to buildings and
infrastructures.
Landslides may occur during an earthquake for steep sloping areas underlain by loose or soft
rock, like the Eastern San Gabriel Mountains in California that will cause damage to buildings and
infrastructures.
Surface Fault Rupture
Shallow fault lines in California and elsewhere can breakthrough the ground surface as they
displace against each other during an earthquake, which will cause damage to buildings and
infrastructures crossing that fault. On the other hand in the Midwestern States, the New Madrid
Fault is too deep to breakthrough the ground surface.
Shallow fault lines in California and elsewhere can breakthrough the ground surface as they
displace against each other during an earthquake, which will cause damage to buildings and
infrastructures crossing that fault. On the other hand in the Midwestern States, the New Madrid
Fault is too deep to breakthrough the ground surface.
Tsunamis
Major offshore earthquakes that displace the ocean floor can generate a tsunami that may affect buildings
and other structures located within few miles from the shore line. Tsunamis are potentially dangerous
where the United States’ coastlines are vulnerable, but tsunamis are infrequent and a mega tsunami
similar to the one that followed the 2011 Tohoku Earthquake in Japan and devastated the north east coast
of Honshu is rare. Areas at greatest risk are actually within few miles from the West Coast having
elevations less than 25 feet above the Pacific Ocean level. Homeowners and business owners living and
working near the shoreline may check the available tsunami information in their area by contacting the
local emergency management office, the National Weather Service office, or the American Red Cross
chapter. Tsunami insurance for homes and businesses is available through the National Flood Insurance
Program (NFIP) by purchasing flood insurance that specifically includes losses due to tsunamis.
Tsunami Video
Tsunami video on YouTube at http://www.youtube.com/watch?v=_b-2iByqHVI showing the devastation
of Kesennuma Port in Japan during Tohoku Earthquake demonstrates that a tsunami alert device is
essential for people living near the coast. For instance, an emergency radio like that of the United States
National Oceanic and Atmospheric Administration simply known as NOAA weather radio would be a cheap
and good option.
Tsunami Alert
With the advancement of technology, an alternative to the NOAA weather radio would be “Disaster Alert”
which is a free application available to Android-based and Apple-based mobile device users. It is
published by the Pacific Disaster Center (PDC) that makes information on worldwide hazards and
disasters. You can view PDC active hazards on an interactive map or in a list format, and to click through for
more details. Active hazards are updated every five minutes providing real-time data events on 12 different
types of hazard: Drought, Earthquake, Flood, High Surf (Hawaii), High Wind (Hawaii), Man Made, Marine,
Storm, Cyclone, Tsunami, Volcano and Wildfire. The events in the system have been designated as
potentially hazardous to people, property, or assets. The data is compiled from authoritative sources,
including NOAA’s: National Weather Service, Tropical Prediction Center, National Hurricane Center, and
Pacific Tsunami Warning Center, as well as the Naval Pacific Meteorology and Oceanography Center, Joint
Typhoon Warning Center, U.S. Geological Survey's National Earthquake Information Center and Volcano
Hazards Program, and the Global Volcanism Program at the Smithsonian Institution.
Major offshore earthquakes that displace the ocean floor can generate a tsunami that may affect buildings
and other structures located within few miles from the shore line. Tsunamis are potentially dangerous
where the United States’ coastlines are vulnerable, but tsunamis are infrequent and a mega tsunami
similar to the one that followed the 2011 Tohoku Earthquake in Japan and devastated the north east coast
of Honshu is rare. Areas at greatest risk are actually within few miles from the West Coast having
elevations less than 25 feet above the Pacific Ocean level. Homeowners and business owners living and
working near the shoreline may check the available tsunami information in their area by contacting the
local emergency management office, the National Weather Service office, or the American Red Cross
chapter. Tsunami insurance for homes and businesses is available through the National Flood Insurance
Program (NFIP) by purchasing flood insurance that specifically includes losses due to tsunamis.
Tsunami Video
Tsunami video on YouTube at http://www.youtube.com/watch?v=_b-2iByqHVI showing the devastation
of Kesennuma Port in Japan during Tohoku Earthquake demonstrates that a tsunami alert device is
essential for people living near the coast. For instance, an emergency radio like that of the United States
National Oceanic and Atmospheric Administration simply known as NOAA weather radio would be a cheap
and good option.
Tsunami Alert
With the advancement of technology, an alternative to the NOAA weather radio would be “Disaster Alert”
which is a free application available to Android-based and Apple-based mobile device users. It is
published by the Pacific Disaster Center (PDC) that makes information on worldwide hazards and
disasters. You can view PDC active hazards on an interactive map or in a list format, and to click through for
more details. Active hazards are updated every five minutes providing real-time data events on 12 different
types of hazard: Drought, Earthquake, Flood, High Surf (Hawaii), High Wind (Hawaii), Man Made, Marine,
Storm, Cyclone, Tsunami, Volcano and Wildfire. The events in the system have been designated as
potentially hazardous to people, property, or assets. The data is compiled from authoritative sources,
including NOAA’s: National Weather Service, Tropical Prediction Center, National Hurricane Center, and
Pacific Tsunami Warning Center, as well as the Naval Pacific Meteorology and Oceanography Center, Joint
Typhoon Warning Center, U.S. Geological Survey's National Earthquake Information Center and Volcano
Hazards Program, and the Global Volcanism Program at the Smithsonian Institution.
Fire Hazards
Earthquakes in urban and suburban areas are often followed by destructive fires because of gas
lines break and electrical shorts that may quickly spread due to clogged roads and collapsed
bridges that prevent firefighter’s access, or due to damaged water tanks that limit water for
firefighting. The earthquake picture (photo 3) shows a completely destroyed steel house at Suma
Ward where the entire neighborhood was burned after Kobe Earthquake.
Earthquakes in urban and suburban areas are often followed by destructive fires because of gas
lines break and electrical shorts that may quickly spread due to clogged roads and collapsed
bridges that prevent firefighter’s access, or due to damaged water tanks that limit water for
firefighting. The earthquake picture (photo 3) shows a completely destroyed steel house at Suma
Ward where the entire neighborhood was burned after Kobe Earthquake.
Hazardous Materials Release
Earthquake damage to refineries and other chemical storage and distribution systems, research
and industrial laboratories, and manufacturing plants can cause releases of hazardous materials
that may be flammable or toxic, thus threatening the life safety in a large area.
Earthquake damage to refineries and other chemical storage and distribution systems, research
and industrial laboratories, and manufacturing plants can cause releases of hazardous materials
that may be flammable or toxic, thus threatening the life safety in a large area.
Chemical Hazards Release
Hazardous chemicals may also be released from the garage and/or utility room from homes in the
neighborhood, threatening the life safety locally. Chemical hazards may be flammable like paints,
gasoline and propane tanks; irritants like bleach or ammonia; or toxic like lawn and garden
insecticides, solvents, adhesives, and lubricants. Hazardous chemicals do in fact cause acute
and/or chronic health effects and, consequently, are health hazards. Acute heath effects appear
quickly after brief exposure to the chemical hazard, while chronic health effects appear during
and/or after long-term exposure.
Hazardous chemicals may also be released from the garage and/or utility room from homes in the
neighborhood, threatening the life safety locally. Chemical hazards may be flammable like paints,
gasoline and propane tanks; irritants like bleach or ammonia; or toxic like lawn and garden
insecticides, solvents, adhesives, and lubricants. Hazardous chemicals do in fact cause acute
and/or chronic health effects and, consequently, are health hazards. Acute heath effects appear
quickly after brief exposure to the chemical hazard, while chronic health effects appear during
and/or after long-term exposure.
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Seismic Activity at Home
Earthquake prediction in the United States is an ongoing research by the United Sates Geological Survey
(USGS). A USGS earthquake map is shown in figure 1 below where a moderate earthquake activity is
represented by the yellow and orange colors. Strong seismic activity is represented by the darkest colors
(red and brown).
Earthquake prediction in the United States is an ongoing research by the United Sates Geological Survey
(USGS). A USGS earthquake map is shown in figure 1 below where a moderate earthquake activity is
represented by the yellow and orange colors. Strong seismic activity is represented by the darkest colors
(red and brown).
Seismic activity at your home or business which
may lead to earthquake damage is due to the three
main processes illustrated in figure 2 which are the
fault rupture mechanism that initiates from the
hypocenter, the propagation of seismic waves
within the earth’s crust, and soil amplification at the
top layers of the earth’s surface. Therefore, the
intensity of ground shaking that a building will
experience during an earthquake is a function of
three main factors:
may lead to earthquake damage is due to the three
main processes illustrated in figure 2 which are the
fault rupture mechanism that initiates from the
hypocenter, the propagation of seismic waves
within the earth’s crust, and soil amplification at the
top layers of the earth’s surface. Therefore, the
intensity of ground shaking that a building will
experience during an earthquake is a function of
three main factors:
- The earthquake magnitude. Larger earthquake magnitudes would develop stronger ground
shaking that affects much larger areas. Figure 3 illustrates the influence of earthquake
magnitude on a site 7 miles from the southwestern segment of the New Madrid Fault. - The closest distance from the segment of the fault that ruptured to the building. Violent back-
and-forth ground shaking may be expected within 20 miles from the ruptured fault segment.
Figure 4 illustrates the influence of distance on two sites 3 and 7 miles from the southwestern
segment of the New Madrid Fault. - The depth and the types of soil materials from the ground surface to the base rock affect the
nature of the surface ground shaking. Soft soils amplify and prolong the shaking (e.g. San
Francisco Bay Area), even at great distances from the ruptured fault. On the other hand, hard
bedrocks do not amplify the shaking. Figure 5 illustrates the soil amplification potential on a
site 8 miles from the southwestern segment of the New Madrid Fault. Deep soils in valleys
and sedimentary basins (e.g. Mississippi River Valley and Los Angeles Basin) shake more
than bedrock in the hills as a result of the persistent shaking where the seismic waves are
trapped and reverberate. Unfortunately most urban development is in these valleys and
basins.
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