On Saturday, October 12th, Costa Rica experienced a significant seismic event that rattled homes and nerves across the country, particularly in the province of Guanacaste. At 11:43 a.m., a powerful 6.6 magnitude earthquake struck 60 kilometers west of Tamarindo, according to the Volcanological and Seismological Observatory of Costa Rica (OVSICORI). This tremor was followed by a second earthquake of magnitude 5.2 at 12:12 p.m., originating from the same area.
The quake was widely felt not only in Guanacaste but also in other parts of Costa Rica, including the Nicoya Peninsula and the Central Valley. In the hours following the initial earthquake, Costa Ricans took to social media to share their experiences and to report the tremors from various regions.
Let’s break down what happened, what the experts are saying, and what you should expect in the coming days.
The Earthquake and Its Seismic Sequence
The 6.6 magnitude earthquake that shook Guanacaste was no small event. With its epicenter located offshore, 60 kilometers west of Tamarindo, it struck at a depth of 45 kilometers, according to OVSICORI. This depth places the earthquake within the Cocos Plate, which is subducting beneath the Caribbean Plate, a process that generates substantial compressive forces and leads to seismic activity in the region.
The Volcanological and Seismological Observatory of Costa Rica (OVSICORI) later confirmed that the earthquake initiated a seismic sequence—a series of smaller aftershocks—along the fault lines off the coast of Santa Cruz in Guanacaste. In fact, more than 53 aftershocks were recorded within just hours of the initial quake.
According to Esteban Chaves, a seismologist at OVSICORI, the earthquake and subsequent aftershocks are part of a natural process following the release of tectonic stress between the Cocos and Caribbean Plates. “This system of compressive forces is what generated the rupture of today’s earthquake and the ongoing seismic activity,” Chaves explained.
Aftershocks: What to Expect
After a 6.6 magnitude earthquake, aftershocks are expected, and they can vary in strength. These aftershocks can feel unnerving, but seismologists stress that this is a normal process following a major seismic event.
By 5 p.m. on the day of the earthquake, OVSICORI had already recorded over 100 aftershocks, some of which were strong enough to be felt by residents in Nicoya and even the Central Valley. Fortunately, the intensity and frequency of aftershocks typically diminish over time, although smaller tremors can continue for days or even weeks following a large quake.
Experts from OVSICORI and the National Tsunami Monitoring System (SINAMOT) reassured the public that there is no tsunami threat associated with this earthquake, so there’s no need to worry about coastal evacuations. However, residents are advised to stay informed and prepared for possible tremors.
The Science Behind the Earthquake
The Cocos Plate is a major tectonic plate located off the Pacific coast of Central America. As it subducts beneath the Caribbean Plate, it generates compressive forces that can result in seismic activity, particularly in regions like Guanacaste and the Nicoya Peninsula, which are situated near the plate boundary.
This region of Costa Rica is no stranger to earthquakes. In fact, the Nicoya Peninsula is one of the most seismically active areas in the country. Historically, Costa Rica has experienced significant earthquakes in this region, and experts have long monitored the tectonic dynamics that make it so vulnerable to seismic events.
According to seismologist Esteban Chaves, the 45-kilometer depth of the earthquake was a key factor in its intensity. While deeper earthquakes tend to be less damaging than shallow ones, the depth of this particular quake still made it widely felt across the country.
Chaves also explained that the earthquake was caused by the compressive forces created by the ongoing subduction of the Cocos Plate beneath the Caribbean Plate. “The rupture occurred as these plates pushed against each other, resulting in today’s earthquake,” Chaves stated. “We can expect to see more aftershocks, but they should gradually decrease in both magnitude and frequency.”
Social Media Response and Public Reactions
As soon as the earthquake hit, Costa Ricans took to social media to share their experiences and report on the tremors. Reports poured in from various regions, indicating that the quake was felt not just in Guanacaste but also in the Central Valley, San José, and other parts of the country.
People described how the shaking disrupted their day, with some commenting on the intensity of the tremors and others sharing photos of minor damage to household items or buildings. Thankfully, there have been no reports of significant damage or injuries, although authorities continue to assess the situation.
Costa Rica’s National Emergency Commission (CNE) quickly issued guidelines urging the public to stay calm, check their homes for structural damage, and prepare for potential aftershocks.
How to Stay Safe During Aftershocks
After a major earthquake like the one experienced in Guanacaste, it’s crucial to be prepared for potential aftershocks. Here are some tips to help you stay safe:
- Stay Indoors: If you’re inside during an aftershock, stay indoors. Find a sturdy piece of furniture to take cover under, such as a table or desk, to protect yourself from falling objects.
- Stay Away from Windows and Glass: Glass windows and doors can shatter during an earthquake, so it’s important to keep your distance to avoid injury.
- Check for Gas Leaks: If you smell gas, turn off your gas supply immediately and contact emergency services. Gas leaks are a common hazard following an earthquake.
- Inspect Your Home: Look for cracks in the walls, damaged support beams, and any other signs of structural damage. If your home has sustained significant damage, it may not be safe to remain inside.
- Stay Informed: Keep updated on the situation by following OVSICORI, SINAMOT, and local authorities. These organizations provide real-time information on aftershocks and potential risks.
Lessons from Costa Rica’s Earthquake History
Costa Rica’s geographic location along the Pacific Ring of Fire makes it susceptible to earthquakes. While the country has implemented strict building codes designed to withstand seismic activity, natural disasters like this still serve as a reminder of the need for preparedness.
In 2012, Costa Rica experienced a 7.6 magnitude earthquake in the Nicoya Peninsula, which also caused significant tremors across the nation. In the years since, Costa Rican authorities have worked to improve disaster response systems and earthquake preparedness, ensuring that the country is better equipped to handle such events.
One lesson learned from past earthquakes is the importance of communication. With the availability of modern technology, Costa Ricans are now able to share information quickly and accurately, helping both authorities and citizens respond to earthquakes and their aftermath more effectively.
Final Thoughts: What Comes Next?
The 6.6 magnitude earthquake that shook Guanacaste on October 12th is a reminder of the seismic realities that Costa Rica faces as a nation. While no one can predict when the next earthquake will hit, the country’s commitment to earthquake preparedness and strong building codes helps mitigate the potential for widespread damage.
As Costa Rica continues to monitor the aftershocks from this event, the message is clear: stay informed, be prepared, and remain vigilant. Seismologists from OVSICORI will continue to track the seismic sequence off the coast of Tamarindo and provide updates as new developments occur.
For now, Costa Ricans can breathe a little easier knowing that the immediate threat of a tsunami has been ruled out and that the frequency and strength of aftershocks are expected to decline in the coming days.
