October 17, 2016
by Leah Greenbaum
Take a look around the room you are in: see any large pieces of furniture? Wall hangings? Heavy light fixtures? Is your computer monitor strapped down? During the 1989 Loma Prieta earthquake in California, 95 percent of the injuries were caused by people falling or being struck by loose objects. During this year’s Great ShakeOut, we at PNSN will also take a look at the non-structural hazards that surround us.
This Thursday, 50 million people will drop, cover, and hold on for the 8th Annual Great ShakeOut, the largest earthquake drill in the world. This year at the PNSN, our motto is “drop, cover, hold on, and do something else too”. We are thinking about other ways that we can enhance our preparedness for a major earthquake. On the SeismoBlog this week, we are outlining a few other strategies to supplement this year’s drill.
The Great ShakeOut gives people a chance to practice the recommended “drop, cover, and hold on” protocol, which involves getting on the ground, taking cover under a table or desk, and holding on until the earthquake is over. That protocol is based on decades of research into how individuals and organizations can best protect themselves during strong earthquake shaking.
On Thursday shortly after our drill on the University of Washington campus, we at the PNSN will do a “hazards hunt” to identify and remedy some non-structural hazards in our lab. From lab equipment, to coffee mugs, to some big, heavy textbooks, we’ve already noticed a few unsecured building contents that could be dangerous and diminish our ability to get back to work in the aftermath of a major earthquake. Luckily, there are many simple and inexpensive fixes that can help keep us safe and reduce our losses—all of them applicable to your home or business, as well.
Here are a few non-structural hazards we’ve already noticed and some potential fixes*:
Computer monitors: Electronics, like computer monitors, are heavy and costly to replace. You can secure your computer monitors and other electronics using nylon straps or buckles. It’s a cheap fix that will help you secure expensive equipment, protect your data, and prevent a falling hazard.
Falling objects: Objects on high shelves (like this giant globe) can become deadly projectiles during an earthquake. You can use earthquake putty (museum wax) to secure your delicate collectibles from falling, breaking, or hurting you during an earthquake. Heavy objects and other breakables can also be moved to lower shelves.
Kitchen: During an earthquake, unsecured cabinet doors are likely to fly open, allowing your cups, plates, and other glassware to fall to the floor. There are a number of latches that will keep your cabinets closed and protect you from broken glass during an earthquake.
Here are some other common hazards you might notice in your home or at your organization:
Water heater: Take a look at your water heater. Is it properly braced to the wall? If it falls over during an earthquake, it can smash your gas line and trigger a gas leak or fire, or smash your water line and start a flood. You can hire a plumber to secure your water heater or do it yourself with this kit.
Wall hangings: During an earthquake, mirrors, picture frames, and other hanging objects can bounce off the walls. Secure them with closed hooks or with screw hooks fastened directly into wall studs.
Here are a few other resources that will walk you though identifying and correcting non-structural hazards to prepare:
- Cascadia Region Earthquake Workgroup’s page on “Protecting Your Home”
- Earthquake Engineering Research Institute’s Guide and Checklist for Nonstructural Earthquake Hazards in California Schools (also relevant to home and office buildings)
- Southern California Earthquake Center’s Earthquake Country Guide
- The New Yorker’s instructive guide “How to Stay Safe When the Big One Comes”
If you hazard hunt with us this Thursday, tag us in a tweet (@pnsn1) and use the hashtag #hazardhunt
*hyperlinked products are examples, not recommendations
October 5, 2016
by Steve Malone
September 12, 2016
by Lauren Burch
September 8, 2016
by Shelley Chestler
August 15, 2016
by Lauren Burch
June 15, 2016
by Steve Malone
May 30, 2016
by Lauren Burch
All the mountains, oceans, and islands on Earth exist because of plate tectonics. Different plate boundaries produce different geologic features: divergent boundaries spread apart to form mid-ocean ridges and rift valleys, transform boundaries slide past one another to form strike-slip faults like the San Andreas, and convergent boundaries collide to form tall mountains, deep trenches, and volcanoes. This type of plate boundary is responsible for the numerous volcanic arcs around the Pacific Rim (often called the “Ring of Fire”), and formed our iconic Cascade Volcanoes. Here in the Pacific Northwest, the Juan de Fuca plate is subducting beneath the North American plate along a convergent plate boundary called the Cascadia Subduction Zone (CSZ). Subduction zones like this are the only fault systems capable of producing very large megathrust earthquakes, but they only do so occasionally - over the last 100 years, there have been 84 earthquakes of magnitude 8.0 or greater worldwide, and only 4 of them were greater than an M9.
The simplest answer to the question “Will there be another large earthquake on the CSZ?” is yes. However, the question of “when” is much more difficult to answer. Seismologists don’t know exactly when the next large earthquake will occur on the CSZ, but we do have a good picture of when they have happened over the past 10,000 years. If we divide 10,000 years by the number of ~M9 earthquakes found in that time period, the average recurrence rate for M9 earthquakes along the CSZ is roughly 550 years. We are 316 years past the last great CSZ earthquake in 1700, and we estimate that there is about a 15 % chance that an M9 will occur on this fault within the next 50 years. However, research on submarine landslide deposits shaken loose by big earthquakes indicate that M8+ earthquakes occasionally strike off the coast of Oregon in between “full rip” M9 events. This research suggests that there is a greater probability of reoccurence of a great earthquake in Southern Oregon than off the Washington coast, but there is not a consensus within the geophysical community as to specifically how much greater the hazard is.