5.3 Earthquake in Upala Alajuela
First reported July 13, 2011 · Updated October 28, 2026
UPALA, Alajuela, July 13, 2011. A sequence of earthquakes struck the Upala and Bijagua area of northern Costa Rica on Tuesday, July 12, starting with a strong shock at approximately 2:11 p.m. The tremors damaged houses, affected bridges and interrupted the flow of the Guacalito River. Although this report carries a July 13 news date, the main earthquake happened the previous afternoon.
The earthquake’s magnitude varies among published scientific catalogs. Initial reports attributed to Costa Rica’s OVSICORI observatory gave a magnitude of approximately 5.1. The University of Costa Rica’s Red Sismológica Nacional, or RSN, later listed the principal July 12 event at magnitude 5.5, followed six minutes later by another event measured at 5.3. The U.S. Geological Survey also catalogs a magnitude 5.5 event at 20:11 UTC, equivalent to 2:11 p.m. in Costa Rica.
These differences are not evidence of separate disasters being confused. Seismic networks can publish different preliminary or final magnitudes depending on the stations and methods used. The event’s date, approximate time and concentration near Bijagua and Upala are well documented.
Damage in northern Costa Rica
The earthquakes affected communities around Bijagua, Armenias, Guacalito, Aguas Claras and Altamira, near the border between the provinces of Alajuela and Guanacaste. Residents described objects falling inside buildings, cracked walls and landslides in nearby hills.
By July 14, La Nación reported that emergency officials had identified damage to 25 homes and problems affecting five bridges. The local water supply also suffered disruption. These were reports compiled after the first day, when the full impact was not yet clear.
The sequence was associated with local faulting, particularly the Caño Negro fault zone. The shaking was shallow, which helps explain why a moderate-magnitude event could have strong effects near its source. The main tremor was followed by additional earthquakes and aftershocks in the same region.
What happened to the Guacalito River?
One of the most unusual reports concerned the Guacalito River, which residents said stopped flowing after the earthquake. The story was initially presented as though a river had disappeared into the earth, but the verified information is more specific.
On July 13, La Nación reported that muddy water began flowing again near Armenias and Guacalito after the riverbed had been dry since the previous day’s shaking. Authorities kept onlookers away from the bridge amid concern about a possible sudden surge of water. The available reporting establishes an interruption and subsequent return of the flow, not a permanently vanished river.
Because earthquakes can trigger landslides and alter streams, authorities often inspect waterways as well as roads and buildings after significant shaking. This particular incident made the river’s condition a priority for local residents.
What happened next
The RSN’s historical earthquake catalog retains the July 12, 2011 Bijagua de Upala earthquake as a magnitude 5.5 event. The catalog records local damage rather than a major national disaster. Its listing provides a durable scientific record of an episode that produced extensive uncertainty in the first hours of news coverage.
For earthquakes in Costa Rica, preparedness remains practical: keep drinking water, flashlights, basic medical supplies and an emergency communications plan available, and follow the National Emergency Commission’s instructions after major shaking.
Questions and answers
Did the Upala earthquake occur on July 12 or July 13, 2011? The main tremor occurred July 12. Reports and follow-up coverage continued on July 13.
Was it magnitude 5.3 or 5.5? Different reports gave different values. The RSN’s later catalog lists the principal event as 5.5 and a second nearby event as 5.3.
Did the river disappear permanently? No. Contemporary reporting documented the Guacalito River’s flow returning on July 13.