While evidence of pyroclastic dams occur within the geologic record, they are best known and studied in relation to recent and current volcanic eruptions. Examples worldwide include associations with El Chichon in Mexico, and the Karymsky Volcano in Russia. The caldera lake associated with Taal Volcano, which was previously open to the East China Sea, was permanently closed by a pyroclastic dam during the 1749 eruption, and remains in equilibrium at a higher level to this day, while the pyroclastic dam comprising the low rim of crater Lake Nyos in Cameroon is considered less stable.