The Big One, Session 1
9 November 2016
Speaker Scott Burns – Professor Emeritus PSU Department of Geology:
• The realization that the Cascades is an active earthquake zone has come about since the 1990’s. The New Yorker article by Kathryn Schulz on 7/20/15 created a lot more interest and action regarding earthquake potential in our area.
• Between 1900 and 2000, there were 10,000 recorded earthquake related deaths per year. Since 2004, there have been 44,000 recorded earthquake related deaths per year.
• An earthquake of 2.5 magnitude can be felt; one of 5.5 magnitude will damage structures. There are 800.000 earthquakes recorded each year. 100,000 of those are felt, 1,000 cause damage and 10 are major disasters.
• Subduction zone earthquakes are the largest in the world. Examples are the 9.2 magnitude event in Alaska in 1964, 9.0 magnitude in Indonesia in 2004, 8.8 magnitude in Chili in 2010, the 7.1 magnitude in Christchurch, NZ in 2010, again in Christchurch in 2011 (6.3 magnitude) and the 9.0 event in Japan in 2011. The “Spring Break Quake” here in our area in 1993 was 5.6 magnitude.
• We live in the ‘Ring of Fire”. Juan de Fuca plate which is 200 miles off the coast has covered up a line of volcanos. Plate growth in the South Pacific has caused many earthquakes; ie New Zealand had 12,000 aftershocks after the Christchurch event. The Christchurch earthquake is of particular interest because of the similarities to our area including the high number of unreinforced masonry buildings. This earthquake resulted in $40 billion in damage, and affecting 60,000 houses.
• The Cascadia subduction zone is 600 miles long and 50 miles wide with no epicenter and runs through California, Oregon, Washington and British Columbia, Canada. The plates (moving toward and under one another) will continue to move and bend until they break. The North American continent is moving 4.5 cm / year and lifting up the Pacific coast. The result of a break will be a Cascadia subduction zone earthquake that will break 50-100 miles wide along the Pacific coast line. When the break occurs, the coast could drop 1-2 meters (6 feet). This event could last 3-4 minutes.
• Earthquakes have four consequences:
• Ground shaking and amplification
• Liquefaction
• Landslides
• Tsunamis
Our area will have major ground shaking but not necessarily ground amplification due to our underlying soils. Liquefaction will definitely be a major problem along all of our rivers. Old landslides tend to reactivate in seismic events and new ones can occur. Our coast line will see a tsunami, but it won’t come as far inland as the Portland area although islands in the Columbia could be submerged.
The Willamette valley is made up of sediments; hard in the winter and soft in the summer. Loose silt goes down 40-50 feet. We have many old landslide locations in our area.
Bill Burns has developed a good landslide potential map call “SLIDO”.
• Our state is also at risk of earthquakes in the “seismogenic crust”; along fault lines. Those will be of lesser magnitude than subduction zone quakes, but have a much higher risk of occurrence. Statistics say 15% chance of a “Big One” (subduction earthquake) in the next 50 years and a 37% chance of a lesser one along a fault line in next 50 years. We may get up to 5 minutes warning for the fault line type.
We are between two fault lines:
• Oatfield on Beaverton side
• Portland Hills on Columbia River side
In addition, there is a large facet at the base of Cornelius Pass Road.
• Historic records show an “orphan tsunami” in Japan in 1700. That would have been caused by our last “Big One”. Archeological evidence suggests a big earthquake every 500 years. There have been 41 Cascadia subduction zone earthquakes in the last 10,000 years; 19 of them were “full margin” events (8.7-9.2 magnitude).
• No seismic provision in building codes before 1993/1994. City and state are focusing on schools and other public structures. Many bridges need retrofit work.
• Past evidence indicates that wells and trees are generally able to hold up, although branches will break and fall.
• 90% of fuel for this area comes through Linnton – very high liquefaction potential in that area but there is nothing in the works for remedy (owners not willing, state not forcing).
• There is an app in beta testing for phones that will give up to 5 minutes warning for earthquakes occurring along fault lines and will also be effective for subduction quake. PSU is tied into it.
• City of Portland has NET (Neighborhood Emergency Teams) organization in place; Skyline Grange is working on getting that extended to our neighborhood. Neighbors will be first responders.
• City and state estimate up to 1 month to restore public water, 6 months to restore public sewer, 1-2 months for electrical service to be restored and 6 months for highways to be restored. Rural areas such as ours will potentially see longer times before services are restored.
• Personal preparations should include:
• Earthquake and landslide insurance for your home
• Strap down your house (seismic retrofit)
• Strap down hot water heater (mandated by code)
• Gas shut off valve (“California” valve is automatic shut off)
• Medical kit including surplus prescription medications
• Food and water sufficient for at least two weeks
• Flashlight and shoes by your bed
• Toilet paper
• See the Red Cross list for a good kit list: [http://www.redcross.org/get-help/prepare-for-emergencies/be-red-cross-ready/get-a-kit]
• The more prepared we are, the less loss of life and property we will experience.
• In a subduction earthquake, everyone will be knocked to the ground. The Big One could last 3-4 minutes. If you are in your house or another building, get under something (not a door frame). DUCK COVER & HOLD ON. If you can’t get under something, get next to a loadbearing, interior wall – away from windows. If you are outside, get in an open area away from buildings and trees if possible. As soon as quake is over, you should get out of the house until you’re sure it’s structurally safe.
Speaker Jeff Rubin – TVF & R Emergency Manager:
• Lots of information on website – TVFR.com
• TVF&R has served during 3 declared disasters since 2001
• Place completed Red Emergency Folder for each person on fridge. 75% of calls to TVF&R are medical related.
• After a subduction zone earthquake, it will take hours to days for TV&R to understand what has happened
• Suggests we keep a surplus of necessary medications, food and water for 2-4 weeks, clothes, pet food. Store food supplies in climate controlled area.
• The realization that the Cascades is an active earthquake zone has come about since the 1990’s. The New Yorker article by Kathryn Schulz on 7/20/15 created a lot more interest and action regarding earthquake potential in our area.
• Between 1900 and 2000, there were 10,000 recorded earthquake related deaths per year. Since 2004, there have been 44,000 recorded earthquake related deaths per year.
• An earthquake of 2.5 magnitude can be felt; one of 5.5 magnitude will damage structures. There are 800.000 earthquakes recorded each year. 100,000 of those are felt, 1,000 cause damage and 10 are major disasters.
• Subduction zone earthquakes are the largest in the world. Examples are the 9.2 magnitude event in Alaska in 1964, 9.0 magnitude in Indonesia in 2004, 8.8 magnitude in Chili in 2010, the 7.1 magnitude in Christchurch, NZ in 2010, again in Christchurch in 2011 (6.3 magnitude) and the 9.0 event in Japan in 2011. The “Spring Break Quake” here in our area in 1993 was 5.6 magnitude.
• We live in the ‘Ring of Fire”. Juan de Fuca plate which is 200 miles off the coast has covered up a line of volcanos. Plate growth in the South Pacific has caused many earthquakes; ie New Zealand had 12,000 aftershocks after the Christchurch event. The Christchurch earthquake is of particular interest because of the similarities to our area including the high number of unreinforced masonry buildings. This earthquake resulted in $40 billion in damage, and affecting 60,000 houses.
• The Cascadia subduction zone is 600 miles long and 50 miles wide with no epicenter and runs through California, Oregon, Washington and British Columbia, Canada. The plates (moving toward and under one another) will continue to move and bend until they break. The North American continent is moving 4.5 cm / year and lifting up the Pacific coast. The result of a break will be a Cascadia subduction zone earthquake that will break 50-100 miles wide along the Pacific coast line. When the break occurs, the coast could drop 1-2 meters (6 feet). This event could last 3-4 minutes.
• Earthquakes have four consequences:
• Ground shaking and amplification
• Liquefaction
• Landslides
• Tsunamis
Our area will have major ground shaking but not necessarily ground amplification due to our underlying soils. Liquefaction will definitely be a major problem along all of our rivers. Old landslides tend to reactivate in seismic events and new ones can occur. Our coast line will see a tsunami, but it won’t come as far inland as the Portland area although islands in the Columbia could be submerged.
The Willamette valley is made up of sediments; hard in the winter and soft in the summer. Loose silt goes down 40-50 feet. We have many old landslide locations in our area.
Bill Burns has developed a good landslide potential map call “SLIDO”.
• Our state is also at risk of earthquakes in the “seismogenic crust”; along fault lines. Those will be of lesser magnitude than subduction zone quakes, but have a much higher risk of occurrence. Statistics say 15% chance of a “Big One” (subduction earthquake) in the next 50 years and a 37% chance of a lesser one along a fault line in next 50 years. We may get up to 5 minutes warning for the fault line type.
We are between two fault lines:
• Oatfield on Beaverton side
• Portland Hills on Columbia River side
In addition, there is a large facet at the base of Cornelius Pass Road.
• Historic records show an “orphan tsunami” in Japan in 1700. That would have been caused by our last “Big One”. Archeological evidence suggests a big earthquake every 500 years. There have been 41 Cascadia subduction zone earthquakes in the last 10,000 years; 19 of them were “full margin” events (8.7-9.2 magnitude).
• No seismic provision in building codes before 1993/1994. City and state are focusing on schools and other public structures. Many bridges need retrofit work.
• Past evidence indicates that wells and trees are generally able to hold up, although branches will break and fall.
• 90% of fuel for this area comes through Linnton – very high liquefaction potential in that area but there is nothing in the works for remedy (owners not willing, state not forcing).
• There is an app in beta testing for phones that will give up to 5 minutes warning for earthquakes occurring along fault lines and will also be effective for subduction quake. PSU is tied into it.
• City of Portland has NET (Neighborhood Emergency Teams) organization in place; Skyline Grange is working on getting that extended to our neighborhood. Neighbors will be first responders.
• City and state estimate up to 1 month to restore public water, 6 months to restore public sewer, 1-2 months for electrical service to be restored and 6 months for highways to be restored. Rural areas such as ours will potentially see longer times before services are restored.
• Personal preparations should include:
• Earthquake and landslide insurance for your home
• Strap down your house (seismic retrofit)
• Strap down hot water heater (mandated by code)
• Gas shut off valve (“California” valve is automatic shut off)
• Medical kit including surplus prescription medications
• Food and water sufficient for at least two weeks
• Flashlight and shoes by your bed
• Toilet paper
• See the Red Cross list for a good kit list: [http://www.redcross.org/get-help/prepare-for-emergencies/be-red-cross-ready/get-a-kit]
• The more prepared we are, the less loss of life and property we will experience.
• In a subduction earthquake, everyone will be knocked to the ground. The Big One could last 3-4 minutes. If you are in your house or another building, get under something (not a door frame). DUCK COVER & HOLD ON. If you can’t get under something, get next to a loadbearing, interior wall – away from windows. If you are outside, get in an open area away from buildings and trees if possible. As soon as quake is over, you should get out of the house until you’re sure it’s structurally safe.
Speaker Jeff Rubin – TVF & R Emergency Manager:
• Lots of information on website – TVFR.com
• TVF&R has served during 3 declared disasters since 2001
• Place completed Red Emergency Folder for each person on fridge. 75% of calls to TVF&R are medical related.
• After a subduction zone earthquake, it will take hours to days for TV&R to understand what has happened
• Suggests we keep a surplus of necessary medications, food and water for 2-4 weeks, clothes, pet food. Store food supplies in climate controlled area.
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