A magnitude 4.8 earthquake struck central Chile at 15:17 on Monday, October 12. It was felt in at least the Valparaíso, Metropolitan and O'Higgins regions.
T13 reported the earthquake during the afternoon. According to the National Seismological Center (CSN) at the University of Chile, the epicenter was 16 kilometers southwest of San Antonio, in the Valparaíso Region, at a depth of 41 kilometers.
The first CSN report, posted on X by the @Sismos_CSN account, was preliminary and gave a magnitude of 4.6, with an epicenter 19 kilometers southwest of San Antonio and a depth of 37 kilometers. The agency later revised the data to the final values.
The National Disaster Prevention and Response Service (Senapred) classified the earthquake as moderate in intensity and began collecting reports of intensity on the Mercalli scale, according to La Tercera.
In the Valparaíso Region, the highest intensity was recorded in Casablanca, at intensity V. Quilpué and Quillota recorded IV. In the Metropolitan Region, Santiago recorded III.
In O'Higgins, Litueche reached intensity IV, while Rancagua, Graneros, Machalí, Olivar and Navidad recorded III.
Magnitude and intensity measure different things. Magnitude refers to the energy released and has a single value for each event. Intensity measures the effects on people and structures, and varies according to the distance from the epicenter, the soil type and the buildings in each location.
According to the CSN, in Chile a seismic event is considered an earthquake when it causes structural damage, meaning when it reaches intensity VII or higher on the Modified Mercalli scale. None of the sources consulted reported damage or injuries following Monday's earthquake, and Senapred had not published any further updates.