Janice R. Andrews
WEST COPALIS BEACH, WA The seismologist for Washington state, Harold Tobin, was closely monitoring the situation when Japan issued its first-ever “megaquake” warning recently. Following an earthquake of a magnitude of 7.1 in the southern island of Kyushu, an advisory was issued. The main worry was that this event would set off a devastating earthquake in Japan’s most vulnerable fault, the Nankai Trough, even if it didn’t inflict much damage. According to scientists, a breach in this zone might cause tsunami waves that reach heights of 100 feet and kill hundreds of thousands of people.
Seismologists in Japan and throughout the U.S. West Coast are wondering if these minor quakes are a hint that “The Big One” is approaching. Is this a hint that a major tragedy is about to happen? Japan reacted quickly, with authorities closing beaches, postponing public gatherings, and urging residents to stockpile emergency supplies. Although there is no such system in place in the United States, experts like Tobin are debating whether and how to alert the public.
Tobin adds, “We don’t want to cause unjustified panic,” but the danger of not getting people ready is just as great. In the United States, seismologists are still working out how to handle this difficult, crucial decision-making process, particularly as research on earthquake warning signals progresses.
Cascadia: The Hidden Threat to America
The Cascadia subduction zone, a fault akin to Japan’s Nankai Trough, poses a serious danger to the U.S. West Coast. The Cascadia fault, which stretches from Northern California to Vancouver Island, is capable of producing a magnitude 9.0 earthquake and a catastrophic tsunami that, in the opinion of the Federal Emergency Management Agency (FEMA), may kill over 14,000 people in Oregon and Washington alone.
Seismologists have been closely examining this fault because they know that time is of the essence. “This is going to be the largest natural disaster in the history of our nation,” states Washington State’s head of emergency management, Robert Ezelle. The United States, however, is not as prepared as Japan, which has more sophisticated warning systems. U.S. seismologists would have to make a snap decision about whether to notify the public if a smaller earthquake or precursor event happened close to Cascadia, as was recently the case in Japan.
Recognizing the Warning Indices
When tectonic plates move, the earth’s crust fractures along fault lines, resulting in earthquakes. Scientists are starting to comprehend possible warning signals for big earthquakes, such as those anticipated from Cascadia. One such indication is the appearance of smaller, earlier earthquakes, also known as slow-slip events or foreshocks, which are minute motions that can only be picked up by extremely sensitive equipment.
Even when scientists detect indications of increasing seismic activity, it can be challenging to distinguish between signals that point to regular tectonic movement and those that suggest an impending major earthquake since the science of earthquake forecasting is still in its infancy. The question of when to issue warnings is complicated by this ambiguity. Tobin states, “We’re getting closer to knowing the clues, but it’s not enough to be certain.”
After a magnitude-7.8 earthquake struck New Zealand in 2016, scientists noticed faint tremors coming from the Hikurangi subduction zone, a significant fault close to Wellington. These oscillations suggested a slow-slip event, in which tectonic plate movement occurs without producing a great deal of shaking. Scientists were on high alert for weeks following these slow-slip episodes, which they believe may presage greater quakes. Luckily, there was no significant earthquake that followed, but the incident made the choice of whether to issue a warning more important.
What’s at Risk in the Cascadia Subduction Zone?
The destruction caused by a large-scale earthquake in the Cascadia subduction zone would be enormous. According to experts, the first trembling would continue for up to five minutes, after which enormous tsunami waves would slam into coastal communities. Over 100,000 people would be hurt, 620,000 structures would be damaged or destroyed, and the collapse of the infrastructure would make emergency response operations extremely difficult, according to FEMA projections.
“We’re just not ready,” Ezelle remarks. Because of the extent of the damage, residents in communities along the West Coast are being encouraged to get ready to live independently for at least two weeks.
Understanding the Cascadia fault’s mechanics and the possible indicators of a big earthquake are key priorities for seismologists. For future readiness, their research—which includes installing advanced monitoring equipment, researching previous earthquake data, and more meticulously charting the fault—is essential.
New Information, New Choices
Mapping the Cascadia fault has advanced significantly in recent years because to the efforts of seismologists like Harold Tobin. It is currently known that the fault is broken into four segments, each of which has the potential to cause an earthquake of magnitude 8 or greater. These parts might break apart separately or all at once, and every situation has an own set of dangers and deadlines.
However, identifying the problem is only one part of the puzzle. Enhancing this underwater fault’s monitoring is the next phase. The U.S. has only started implementing comparable technology, but Japan has a sophisticated network of seabed sensors to detect seismic activity. Recently, Tobin and his associates were able to obtain $10.6 million in government funds in order to extend the sensor network along the coast of Oregon. These new tools will provide scientists vital information on the behavior of the fault, enabling them to identify anomalous, possibly harmful movements and define typical activity.
Seismologists might be able to tell when the fault is preparing for a significant rupture with improved monitoring. For example, slow-slip episodes are being investigated closely as a potential indicator of big earthquakes. The tectonic plate motions that are slow and gradual may indicate the build-up of pressure before to the fault’s ultimate rupture.
The Great Debate: When Should the Public Be Warned?
One of the hardest challenges for seismologists is determining when to warn the public about a large earthquake’s elevated risk. Scientists must consider the possibility of averting widespread panic vs the possibility of saving lives if they identify warning indicators, such as a slow-slip event or foreshock.
It’s important not to cry wolf, Tobin says. However, the repercussions of doing nothing are just as dire. Public authorities acted quickly after Japan’s latest “megaquake” alert, shutting beaches and postponing activities even though the likelihood of a significant earthquake was rather low. Since equivalent procedures are not in place in the United States, it could be more challenging to develop this type of quick, preventive action there.
Scholars such as Laura Wallace, who examined the 2016 earthquake in New Zealand, are aware of the difficulty involved in making these crucial judgments. Wallace and her colleagues calculated that there was an 18-fold increased chance of a major earthquake after that one, although none ever occurred. She wonders, expressing the uncertainty that still surrounds seismologists, “Which of these slow-slip events are going to trigger the next big one?”
Getting Ready for the Future
Public awareness and readiness will be crucial as research into seismic warning indicators advances. Seismologists anticipate being able to make more precise predictions in the future with improved fault monitoring and knowledge, such as that of Cascadia. However, the issue still stands: When should they inform the public?
Right now, it’s better to be ready for anything that can go wrong. Communities along the West Coast of the United States should be prepared for a significant earthquake and tsunami since “The Big One” might happen at any time.
Seismologists like Tobin and Wallace are working on their studies in the meantime in the hopes that when the next set of warning indicators appears, they will be prepared with the information and resources needed to raise the alarm.
