On November 30, 2018, at approximately 11:29 am CST, a 7.0 magnitude earthquake shook the Alaskan town of Anchorage and the surrounding area. Roads were cracked, power was lost, and damage was done. But one thing that kept being repeated in reports and on social media was the fact that there was not much structural damage. When searching for this information there was nothing that would give a solid answer.
On December the 1st, we at Hill Country Network, reached out to Meadow Bailey, with the DOT, to ask about what made their buildings stable enough to withstand this earthquake. Bailey, who was serving as a contact person during this time of crisis, agreed to answer some of the questions we had by contacting her team of people who pulled together the answers to the questions.
The question of their building code was asked because when researching articles, there were several online statements that mentioned the building code. One stated that even though the building code was harsh, it really did work. Another stated that it was worth the extra money to save their business.
The response from Alaska was they use the International Building Code (IBC) for commercial structures, like most, if not all of the United States and used the Uniform Building Code (UBC) prior to the initial IBC in 2000. Residences are usually built to the International Residential Code. While these codes are not unique, they have been honed after each earthquake where major damage has occurred.
“Design for large earthquakes and high wind speeds have been a priority for decades. Many older and substandard buildings in Alaska were removed from the inventory by the 9.2 magnitude earthquake in 1964. Alaska also does not have some of the older problematic designs found in other areas, like non-reinforced masonry.” stated the Alaskan team.
Another question was how were so many homes able to go through the quake without much damage. “Homes in Alaska have the same hurricane clips found in the Southern US and hold downs in shear walls, which make them more resilient than in areas with lighter detailing requirements.”
Another question we had was about the foundation and if there are any special requirements in Alaska. “Most structures in Alaska are primarily wood or steel, but also concrete and concrete masonry. Due to seismic design requirements, there are more stringent detailing requirements in Alaska, similar to that required in California. The major difference in the foundations is that we bury them deeper in the soil to resist frost action.”
Other than the IBC, the International Code Council (ICC), which references documents defining design loads written by the American Society of Civil Engineers, is also used to help with structural stability. The state of Alaska does not adopt structural amendments as some do. Primarily, it is to define loads but does address local construction practices.
“Additionally, Alaska’s larger cities/towns have strong building department code officials, plan reviewers and construction inspectors. The larger cities have their own code ordinance in place. Together they provide an additional oversight on building and structural standards.”
The buildings in Alaska are earthquake ready. This should be of interests in our part of the world also, because according to the website ready.gov/earthquakes, even though earthquakes can happen anywhere, the higher risk areas include California, Alaska and the Mississippi Valley. Our risk factor is the New Madrid Fault, which runs
from Illinois to Arkansas but effects all of the Mid-South area.
As of December 5th, per the AkDOT website, they are making headway on repairs to the roads, getting the essential routes open. With frozen soil, it makes the task a bit harder, but they have met challenges and found solutions in record time, per a statement made by Governor Mike Dunleavy.
Many thanks to Meadow Bailey and the team for your response. We will keep Alaska in our thoughts and prayers.
Categories: National News