An earthquake measuring 4.2 on the Richter scale struck northern Spain on Thursday evening, 15 October, and was also felt in several parts of northern Portugal.
The tremor was recorded at 9.34 pm Portuguese time, with its epicentre located approximately 10 kilometres south of Ponferrada, in the Spanish province of León, not far from the Portuguese border.
The Portuguese Institute for Sea and Atmosphere (IPMA) reported that the earthquake occurred at a depth of approximately 16 kilometres.
Although the earthquake originated in Spain, residents in several northern Portuguese towns also felt the ground shaking, particularly in the district of Bragança.
RTP reported that people in Paredes de Coura, Valença, Vila Nova de Cerveira and Melgaço also described feeling the tremor, with some sharing their experiences on social media.
The earthquake attracted attention on both sides of the border, as people tried to find out where the shaking had come from and whether any damage had been reported.
No damage reported
Despite being felt in several locations, there were no immediate reports of significant damage or injuries.
The Portuguese National Emergency and Civil Protection Authority (ANEPC) confirmed to the Lusa news agency that the earthquake had been felt in the Bragança area.
Commander José Costa explained that the authority had not received any reports of damage resulting from the tremor.
On the Spanish side, authorities in León also reported no significant incidents following the earthquake.
Reports continued to emerge on Friday morning, 16 October, with the regional newspaper Mensageiro de Bragança reporting that residents in Bragança, Macedo de Cavaleiros and Chaves had also noticed the shaking.
More than 20 aftershocks recorded in Spain
The earthquake was followed by a series of smaller tremors in Spain during the night.
Europa Press reported on Friday morning that the Spanish National Geographic Institute (IGN) had recorded more than 20 aftershocks in the El Bierzo area of León.
These smaller earthquakes had magnitudes ranging from 1.2 to 2.4 and continued until at least 3.21am Spanish time. Their epicentres were located in several places, including Borrenes and Priaranza del Bierzo.
The main earthquake was also felt across parts of Galicia and Asturias, while the emergency services in Castilla y León received numerous calls from residents reporting the shaking.
The regional Civil Protection director, Irene Cortés, identified Ponferrada, Villamartín de la Abadía and Villar de los Barrios among the locations particularly affected by the tremor.
Despite the number of calls, emergency services confirmed that no injuries or material damage had been reported.
Earthquake intensity in Portugal
The IPMA later confirmed that the earthquake had been felt northeast of Bragança, reaching a maximum intensity of II–III on the Modified Mercalli scale.
Unlike magnitude, which measures the size of an earthquake, the Mercalli scale describes how strongly the shaking is experienced in a particular location.
An intensity of II–III generally means that the movement is weak and may only be noticed by some people, particularly those indoors or sitting still. It is not normally associated with structural damage.
In Spain, the IGN recorded considerably stronger shaking in locations closer to the epicentre, with intensities reaching IV–V in some communities around Ponferrada.
The earthquake was registered by Portugal's national seismic monitoring network, which continuously records seismic activity both within the country and in neighbouring regions.
The IPMA also explains that the initial information released after an earthquake is preliminary and may be updated as more data becomes available.
The public can follow recent earthquakes through the institute's official website, which provides information about their location, magnitude, depth and time of occurrence.