Two rivers near Costa Rica’s Rincón de la Vieja Volcano— the Azul and the Pénjamo—turn milky gray over the weekend, according to reports from local outlets. The color change is attributed to volcanic material being carried into waterways after a period of small eruptions and heavy rain. In both accounts, the rivers’ altered appearance is linked to runoff washing sediment from the volcano’s slopes into the river channels.
Scientists monitoring the volcano record multiple low-level events in the same timeframe, described as steam-driven eruptions. One report states that 23 small steam-driven eruptions were logged over a week, while another notes a specific moderate eruption occurring on July 6 and references additional activity in the days leading up to the weekend’s rain. The strongest event mentioned sends a plume that contributes to the overall volcanic output.
While the reports focus on the river discoloration and ongoing monitoring, they describe the episode as related to ongoing low-intensity volcanic activity combined with rainfall, rather than a single major eruption driving immediate changes.
