To run, or to drop, cover and hold on. That is the question, argues earthquake geologist and Pacific Northwest resident, Chris Goldfinger.
By Chris Goldfinger, Ph.D., Oregon State University (@goldfinger300)
Citation: Goldfinger, G., 2022, Opinion: When the next Cascadia megaquake strikes, here’s what I’ll do, Temblor, http://doi.org/10.32858/temblor.242
On a Friday afternoon in March of 2011, a group of earthquake geologists, myself included, gathered in Kashiwa-Chiba, Japan at the Ocean Research Institute to discuss the 2004 magnitude-9.2 Sumatra earthquake. My talk at this meeting was coming up soon, so I was thinking about what to say.
While Indonesian colleagues were changing slide presentations at the podium — at precisely 2:46 p.m. — an earthquake began. This was the third earthquake that week, and I hoped it would stop soon so we could get on with the meeting. An earthquake as a hazard did not really occur to me, as we were congregated in a new and very stout looking building in Japan, known for its seismic resiliency.
For a full minute, light shaking persisted. Then, it got stronger. At that point, we did what most people naturally do in an earthquake — we left the building. Once outside, we watched the magnitude-9 earthquake unfold during the three minutes of the mainshock, knowing we were seeing a paradigm change for northeastern Japan in real-time. A recording from the meeting captured the beginning of the earthquake and our departure. The initial shaking was so light that the stabilizer on the camera removed it!
Then, a horrible disaster unfolded; a towering tsunami inundated the coast, followed by the meltdown of the Fukushima-Daiichi Nuclear Power Plant over the next several days.
We were fine. There was no local damage, and we were inland of the tsunami zone. But the same could not be said for much of northeastern Japan. Transportation was shut down. The tsunami — larger than expected — had devastated the coastal zone.
At the airport terminal, I watched the Japanese trying to stop the Fukushima meltdown on a jumbo screen. As I flew home, I began to settle down. I also began to see a little bit of light in the tunnel of this disaster. As bad as it was, Japan’s remarkable resilience to earthquakes was apparent.
I began to think that a similar response to an inevitable major earthquake in the U.S. Pacific Northwest — where I live — might be more tractable that I’d thought. If Japan can be this resilient, other countries can be as well. Of course, Japan has a head start of more than a thousand years; their resilience is no accident.
In the U.S., recommendations for protective actions during earthquakes come from state, local and federal agencies. The primary recommendation is an action known as DCHO, or “Drop, Cover and Hold On,” which is printed universally across circulars, pamphlets, websites and other media. But whether DCHO is the best option for the Pacific Northwest, as well as regions with a similar mix of older and newer buildings, is up for debate.
My new plan
In the fall of 2011, mere months after what came to be known as the Great Tohoku Earthquake, I found myself under my desk in the annual “Shake Out” earthquake drill, which many people sign up for and promptly ignore. I thought about the Tohoku earthquake, and wondered how long I’d have to wait under my desk for the damaging surface waves to arrive should a similarly destructive earthquake strike the nearby Cascadia Subduction Zone. Some quick calculations showed there should be between 45 and 60 seconds of light (P-wave) shaking for an event originating offshore, west of Corvallis, followed by heavy shaking from stronger secondary waves. Our oceanography building is a lift-slab type constructed in the 1960s — likely at risk of collapsing. I knew this and planned to escape from the second-floor window in the event of an earthquake. But there I was, under my desk, practicing something that wasn’t actually in my plan at all.
The disconnect became apparent.
Should an earthquake strike offshore in Cascadia, my experience would likely mirror how my colleagues and I experienced the 2011 Tohoku earthquake in Japan. Corvallis is well inland, and its residents would feel the light shaking ahead of the trailing, damaging waves. In future versions of Earthquake Early Warning (EEW) systems, Corvallis could see warning times of up to 90-120 seconds, depending on where the earthquake strikes and if alert thresholds are low (McGuire et al., 2021), while Seattle could have 50-220 seconds, also depending on the epicenter location. Most people who live along the Cascadia subduction zone would have less additional warning.
After my Shake Out experience that year, I thought about the fact that I knew what a magnitude-9 event felt like. My building would likely not collapse in that initial light shaking. However, under the heavy shaking that would chase the initial tremors, I wasn’t so sure the building would endure.
Would I wait under my desk for collapse? Over time, I thought about this a bit more. What about the warnings to avoid evacuation because of the risk presented by falling objects likely to be encountered outside? One day, I walked around the building and found no parapets, large plate glass windows or other obvious falling hazards. The building has parking lots on two sides and open streets on the other two. There were few potential neighboring hazards.
At that moment, I hatched a new plan: At the first light shaking, I would leave the building, grabbing as many of my colleagues as I could on the way out.
Earthquakes come in different flavors
But what about local crustal earthquakes — those that strike, not within the subduction zone, but along smaller, onshore faults? That minute of light shaking, typical of offshore events, wouldn’t exist because these events strike much closer to populated areas and the stronger secondary waves would arrive much faster. These earthquakes can nonetheless be damaging, and DCHO is the safest option, because evacuation can’t happen fast enough.
In my experience during similar local quakes in California, by the time shaking ends, I’m usually still processing what is happening and what to do. This is likely true for most people. Decision time barely exists for nearby crustal earthquakes.
Would I have to decide what type of earthquake I felt to know what action to take? I had to incorporate this into my plan as well. If I found myself on the floor, wondering what was going on, I’d drop, cover and hold on. On the other hand, if I had time to think — possible with light shaking — I’d leave. However, I realized that my evolving personal plan was not recommended by any cognizant entity that I knew. When I spoke to people in emergency management, I got eye-rolling as assurance that DCHO was demonstrably the best protective action.
Taking that as a challenge, I searched the scientific literature for data supporting DCHO. That’s when the surprise came: such literature is very thin and often narrowly focused on the demographics of injuries.
Great volumes of informal websites, pamphlets and PowerPoint presentations point to DCHO, but nearly all these sources reference other agencies, and posit very little data. I found that there is good reason for this information gap.
In many countries, after an earthquake, no one is directly responsible for tabulating what happened to people, or why. Engineers survey damage to assess the performance of structures, not people. Medical records tabulate injuries, but may or may not reference linkages to the earthquake or individuals’ actions when shaking struck. Kano (2005) reviewed injuries from the 2001 magnitude-6.8 Nisqually earthquake that rocked the Seattle-Tacoma area and the 1994 magnitude-6.7 Northridge earthquake that struck Southern California. The paper’s author notes that the extent of injuries resulting from large earthquakes are poorly known because estimates come from incomplete datasets and inconsistent methodologies.
For Nisqually, few details of injuries are available, so how casualty estimates were derived is not clear. Kano cited earlier work that found a higher fatality risk for individuals in multiple-unit apartment buildings and commercial structures — where most of the deaths occurred (Peek-Asa et al., 2003; Mahue-Giangreco et al.; 2001, Durkin, 1996). Being hit or trapped by buildings or debris was the most common cause of fatal injuries. Being struck by falling objects accounted for only 13.2% of non-fatal injuries, whereas falls were the most common cause of lesser injuries, accounting for 27.1% (Durkin and Theil, 1992). Based on these observations, Durkin and Theil (1992) recommended strengthening evacuation routes out of unreinforced masonry buildings as a potentially effective measure to reduce injuries for those trying to evacuate.
Shoaf et al. (1998) investigated injuries from several California earthquakes — Northridge, the 1989 Loma Prieta earthquake and the 1987 Whittier Narrows earthquake — and found that injuries from falls and falling objects dominated. They investigated demographic factors for such injuries, but did not address fatalities. Similar results were documented by Basharati et al (2020) for the 2011 Christchurch earthquake. The psychological and demographic factors of injuries are reported extensively in McBride et al., (2022).
In my search, I found literature on demographic factors influencing injury rates and types — broadly characterized as minor. But, I found very little information regarding protective action outcomes and fatalities. I began to suspect that DCHO was simply an extension of the Cold War recommendation for nuclear attacks by Civil Defense, which, in fact, it is as illustrated in this 1952 film “Duck and Cover.” As the cold war moderated, emphasis shifted from nuclear attack to all hazards, including tornadoes and earthquakes (e.g. VA emergency management, 2015; Homeland Security, 2006).
If little actual evidence supports DCHO, what other protective actions exist, and who advocates for these alternatives?
Both Mexico and Israel have policies that involve a more diverse, situational response, based on their populations’ experiences. In Mexico, a country that has had an earthquake early warning system for more than two decades, the government recommends DCHO for those in second floor or higher locations, and evacuation for people on the ground floor (Godby, 2017). These are the actions practiced by the populace during Mexico City’s annual earthquake drill. Policymakers tailored this response to Mexico’s tectonic setting — an offshore subduction zone with nearby onshore faults. This setting differs distinctly from the settings of the Northridge, Whittier Narrows, Loma Prieta and Christchurch earthquakes. Mexico’s recommendations also consider their earthquake early warning system (SASMEX) as part of the equation.
Recently, Israel also altered its policy. Following a national study informed by the experiences of Israeli teams sent to aid China, Haiti and other locations after earthquakes, Israel dropped the universal DCHO in favor of evacuation. They reasoned that injuries may occur during evacuation, but are typically minor — a conclusion also shown for the Northridge and Loma Prieta events (Rapaport and Ashkenazi, 2019). On the other hand, about 5,000 children died under desks inside collapsed buildings during the 2008 Sichuan earthquake, or shortly after while awaiting rescue (Rapaport and Ashkenazi, 2019). An expert panel reviewed the extant policy and recommended changes for kindergartens and primary and secondary schools. Specifically, the panel recommended evacuation to an open space at the first sign of tremor. If students cannot get outside, they should get to a safe space inside the building. Only if neither of these options is available within a few seconds are students to get under heavy furniture, which is generally unavailable (Rapaport and Ashkenazi, 2019). One factor in Israel’s decision is data from recent earthquakes in countries such as Japan — with a population drilled in protective action — that shows the actual instinctive response of people is to flee (Rapaport and Ashkenazi, 2019 and references therein). In the case of Israel, which also has an earthquake early warning system, warning time may not play a significant role as their hazard is generally crustal earthquakes at shorter ranges, similar to California’s quakes.
The emerging evolution of protective actions in earthquake emergency management appears to be “situational awareness,” which includes a locally derived assessment of the expected earthquake types, the condition of relevant structures, time available for action and other factors. This concept comes from aviation, which requires a constant effort to be aware of all factors to prevent a routine flight from becoming a disaster. With only 120 years of history, our society has had a compressed timeline to make aviation safe, following crash after crash where lessons were learned and improvements were made.
With earthquakes, the process is just beginning, and is much more extended in time. In part, this is because devastating earthquakes don’t happen that often — typically every few hundreds of years for subduction zones and major plate boundary fault systems. The lack of information requires the polar opposite of the one-size-fits-all recommendation of DCHO. An understandable desire for “simple messaging” dominates the recommendations for DCHO. Some countries have realized that this may not be the best practice given a diverse built environment that includes structures at risk of collapse. In what may be a first in the U.S., the Beaverton School District in Oregon, the third largest in the state, has recently adopted a policy similar to that of Israel. They will use evacuation for older structures without retrofits, and DCHO for newer structures built to modern earthquake codes (P. Jewell, pers. comm. 2021).
Fortunately, a comprehensive study that discusses the situational-awareness-approach is available for review. Geohaz (2018) was a report commissioned by the U.S. government through USAID to help work through this complex and confusing issue. The authors’ intent was to produce a document for Haiti and other developing countries, where buildings are generally more prone to collapse. The study reviews and incorporates the material cited above, and much more. Their recommendation, reviewed by a broad panel of experts, is a clear endorsement of the situational awareness approach.
Until earthquake-prone regions such as the Pacific Northwest are as resilient as Japan, they are vulnerable to catastrophic building collapse similar to Haiti, Mexico City and other locales. In such places, simply getting under a desk is likely not adequate. We need an interim solution that has the best chance of saving lives, and a situational awareness approach deserves consideration.
Basharati, S., M. Ardagh, J. Deely, N. Horspool, D. Johnston, S. Feldmann-Jensen, A. Dierckx, and M. Than, 2020, A research update on the demography and injury burden of New Zealand earthquakes between 2010 and 2014: Australasian Journal of Disaster and Trauma Studies, 24, 904 65-73.
Department of Homeland Security, 2006, Civil Defense and Homeland Security: A Short History of National Preparedness Efforts, Washington DC, 26 pp. https://training.fema.gov/hiedu/docs/dhs%20civil%20defense-hs%20-%20short%20history.pdf accessed Feb 9, 2022.
Durkin, M. E., and Thiel, C. C., 1992, Improving Measures to Reduce Earthquake Casualties: Earthquake Spectra, v. 8, no. 1, p. 95-113.
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Correction: The original article mislabeled the in-text reference to McBride et al. (2022) as McBride et al. (2021). It has since been updated and the full citation has been added to the reference list.
Editor’s note: this story has been updated to clarify Earthquake Early Warning alert times for the Pacific Northwest