It is estimated that there are 500,000 detectable earthquakes in the world each year. Of those, 100,000 can be felt, and 100 of them cause damage. According to National Geographic, the underground disposal of wastewater from fracking may also pose a greater risk of seismic activity, especially in the U.S. Southwest and Midwest, where earthquake faults have not been extensively mapped. Fortunately, both companies and individuals can take proactive measures to protect their infrastructure. Whether it's tectonic plates, volcanic activity, or fracking that is responsible for the earthquakes, we can all better prepare ourselves for disasters. By seismically retrofitting our buildings and structures now, we can prevent billions of dollars in damage when another major earthquake strikes.
Oklahoma is on the map for the most seismic activity in the United States. In fact, Oklahoma now experiences twice as many earthquakes per year as California. The panhandle state used to see an average of one earthquake per year with a magnitude exceeding 3.0 on the Richter scale, but now they're observing an average of one per day. What has caused such a drastic increase in earthquakes? While definitive answers have yet to be determined, the most popular suspect is Hydraulic Fracturing, or "fracking." Fracking is a process that involves drilling deep into the ground and injecting fluids at high pressures, fracturing shale rocks 10,000 feet below Earth's surface to release natural gases. These gases then flow into wells, where they are extracted. Fracking produces an estimated 300,000 barrels of natural gas every day. However, considering that the fluid used contains water, sand, and up to 600 chemicals, many also blame it for water contamination, radiation exposure, and earthquakes. While science has not yet been able to conclusively prove whether fracking is responsible for the increased number of earthquakes in the United States, the British Geological Survey reports that "it is well established that fluid injection can induce small earthquakes." Still, scientists argue that correlation does not necessarily imply causation. While many earthquakes have occurred in places with increased fracking, the process is not necessarily the direct cause. Other known factors, such as tectonic plates, volcanic activity, and crustal instability where natural oil and gas deposits are located, could also be to blame.
Earthquake occurrence is no longer a matter of if but when. And while earthquakes can be devastating, there are precautionary measures we can take now to help protect our structures and our safety when another one hits. San Francisco is considering mandatory seismic retrofit work for buildings that are vulnerable to collapse during earthquakes. They have had a voluntary retrofit program in place for a few years, but only about 50 property owners have used it. Proposed legislation would require thousands of San Francisco property owners to retrofit their older, collapse-prone buildings, at an estimated cost of $60,000 to $130,000 each. In a major earthquake, soft-story buildings (multi-story, wood-frame buildings with a garage, large windows, or similar openings on the ground floor) are very likely to be badly damaged, if not completely destroyed. More than 3,000 buildings in San Francisco will have to be retrofitted at the property owners' expense if the proposed legislation passes. While the total work is estimated to cost around $260 million, the retrofits could prevent a damage bill of $1.5 billion when another earthquake hits.
Carbon fiber has become a popular material for seismic retrofitting. The fiber is ten times stronger than steel, yet it adds practically no weight to buildings. A manufacturing facility in the southwestern US needed strengthening for seismic upgrades and lateral shear reinforcement on three reinforced concrete tilt-up walls. Building expansion and changes in use resulted in a significant increase in load requirements for all three walls, and the company chose HJ3's CivilTM hybrid carbon fiber strengthening system for the upgrades. After abrading and priming the three walls, a thickened high-modulus paste was applied, followed by over 30,000 square feet of carbon fabric. The strengthening system increased the strength and ductility of the walls, meeting seismic code requirements, while also saving the client 40% compared to replacement or steel alternative costs. The installation was completed in three weeks, rather than months as replacement or steel alternatives would have taken. By using carbon fiber, 625 tons of steel and concrete were prevented from going to landfills, and more than 36 million gallons of water were saved. Furthermore, 4 million kWh of energy and 1,200 tons of CO2 emissions were prevented from polluting our atmosphere. If you have a building that needs seismic upgrades and want additional information, contact HJ3 at info@HJ3.com.
