Earthquakes: Planning for an unpredictable risk

The public’s perception of earthquake risks understandably differs depending on where they live and how frequently noticeable earthquakes occur there — if ever. Earthquakes are actually happening constantly; there are hundreds around the world every year. Of course, the vast majority are so small they are undetectable by the average person and have no impact on their lives.

But we are reminded regularly of the monumental devastation a major earthquake can cause. The 7.2 quake that hit Haiti in August of 2021 was that year’s most catastrophic quake, with thousands of fatalities and injuries, and massive property and infrastructure damage that can probably never be fully assessed.

While the U.S. has recently been spared the kind of historic losses caused by earthquakes some nations have had to endure, it has certainly felt the destructive power of these events. Many will remember the 1994 event in Northridge, California. That 6.7 magnitude quake, which caused 57 fatalities, thousands of injuries and widespread damage costing at least $20 billion, was the last major quake in the mainland U.S. But you only need look back five years earlier for another example: the 1989 Loma Prieta earthquake that hit the San Francisco Bay area, resulting in 67 deaths and over $5 billion in property damage.

Both the Northridge and Loma Prieta (a 6.9) quakes were very strong, but still under magnitudes rated as “Major” (7.0 to 7.9) and “Great” (8.0 and above) on the Richter scale. That shows that an earthquake does not have to make its mark in the record books to have calamitous effects. Population density and a heavy concentration of buildings and infrastructure can make lower-magnitude quakes dangerous.

Going back to the mid-twentieth century, the largest recorded magnitude earthquake in U.S. history — a massive 9.2 quake — hit Alaska’s Prince William Sound in 1964. The event resulted in a tsunami and caused over 139 deaths and over $2.3 billion in damage when measured in today’s dollars. As tragic as that is, one can only imagine how much larger those dire statistics would have been had a 9.2 event occurred in a more populous area.

Where are earthquakes likely to occur and can we forecast them?

The west coast, and California in particular, is where the scientific community has long suggested the next historic-level earthquake is likely to occur in the U.S., largely due to observations of the San Andreas Fault, which runs through much of the state. However, the U.S. Geological Survey (USGS) tells us we can’t truly predict earthquakes. The Earth’s tectonic plates are like a massive, constantly shifting puzzle. Looking at their history, geologists can make long-term projections, but not true forecasts as experts can for a storm.

Case in point: In December 2021, a swarm (yes, that’s the term used) of more than 50 earthquakes struck near the Oregon coast in just 24 hours. To a layman, that might suggest impending doom – the precursor of the so-called “Big One.” But even though the magnitude of some of those quakes was as high as 5.8, the scientific consensus was either comforting or discomforting (depending on your outlook) in that no direct correlation could be made from this series of quakes to potential future events.

There are three prominent global earthquake zones, but the USGS reminds us earthquakes can happen anywhere and without warning. Projections make it natural to focus on regions where earthquakes have been more common in recent history, but all governments, community organizations and businesses should have an Emergency Response Plan (ERP) for earthquakes. While nothing can contain or control a natural earthquake, a thorough ERP can provide steps that can help mitigate impacts and save lives.

For businesses, company leadership should consult with local authorities on emergency planning, as well as review resources made available by national government organizations, including:

• U.S. Geological Survey
• Occupational Safety and Health Administration
• Federal Emergency Management Agency

Many U.S. government earthquake resources are also coalesced on ready.gov/earthquakes.

Man-made earthquakes: A risk we can manage

Because many earthquakes have begun under the ocean, creating more damage from resulting tsunamis than immediate surface-level destruction, people sometimes refer to “underwater earthquakes,” but these — like most naturally occurring earthquakes — are tectonic or volcanic in origin. (Volcanic earthquakes can be either volcanic-tectonic quakes resulting from a fault near a volcano, or long-period quakes produced by vibrations caused by the movement of magma or other fluids within a volcano.)

But human activity can create earthquakes as well, and while dwarfed by the number of natural earthquakes, man-made quakes are more frequent than you might think. In 2017, a database devoted to these events showed 730 human-triggered quakes over 150 years. Man-made earthquakes can be caused by a number of common industrial activities, including but not limited to:

• Fracking
• Drilling
• Mining
• Construction of water reservoirs and wastewater disposals

In 2016, the USGS released a report showing seven million Americans, mostly in the central and eastern U.S., at risk from induced tremors. It is not always easy to connect human activities to earthquakes when spatial and temporal scales are so large. And events can happen far away from where the human activity took place and/or occur years after that activity.

There is also a distinction made by some experts between human-induced quakes (where the event would not have happened without human activity) and human-triggered events (when a rupture on a pre-existing fault is simply advanced by humans, but the earthquake would have most likely happened without human action at some point). This distinction can lead to debate over the level of human responsibility, but connections are not hard to find.

Let’s look at just one state, Oklahoma, as an example. A Columbia University study linked a 5.6 magnitude earthquake in Oklahoma in 2011 to gas extraction work.A USGS report stated wastewater disposal likely induced a 5.1 quake in the state in February 2016. And though not stating a definitive cause, the USGS also mentioned impacts of human activity in its summary of a 5.8 quake that struck the state just a few months later in 2016, noting, “…we do know that many earthquakes in Oklahoma have been triggered by wastewater fluid injection.”

Globally, the largest earthquake in terms of magnitude that may be attributed — at least in part  — to human activity is the 7.9 quake in Sichuan, China in 2008 where nearly 90,000 lives were lost. Studies from different scientists around the world have suggested the weight of the water in the man-made Zipingpu Dam may have triggered the event earlier than an inevitable earthquake (based on its location near a fault line) would have occurred naturally.

Long term, global sustainability initiatives and potentially historic reductions in fossil fuel use could influence the need for mitigation strategies for man-made earthquakes. Though fracking is a controversial practice on many environmental fronts, the USGS suggests wastewater disposal is a more significant contributor to consequential man-made quakes. As things stand now, however, leaders in industries with potential seismic impacts need to bring in scientific, government and community advisors to take a full and responsible view of many factors, including but not limited to:

•  Natural (tectonic) seismicity in the area where industrial activity might take place (that is to say, the general projections for probability of an event)
•  Projected severity of regional seismicity
•  Vulnerability of people, property and objects to an earthquake of a given magnitude
•  Potential monetary losses from an earthquake event
• Added risk estimation for specific man-made factors influencing seismic risk, including but not limited to: Fracking sites; Wastewater deposits; Gas-sequestration sites; Dams and reservoirs; Large construction sites (e.g., tunnels); Mining sites.

Site risk assessments are essential, not only in deciding whether a project should go forward, but in informing site location, project duration and protection mechanisms to reduce exposures where possible. Risk mitigation (e.g., building retrofitting) and insurance needs also need to be at the forefront of planning.

Business leaders should also consult with their insurance provider or broker to ensure they know what is and what is not covered in the event of an earthquake. This discussion should not be limited to property coverage, as an earthquake may impact workers’ compensation claims, supply chains, liability claims and much more. Companies may also find that some targeted, specialty insurance programs may be able to offer additional protection against potential losses.

Visit the Earthquake Resource Hub for additional insights.