Compared to an intense volcanic eruption on land, when an entire mountain turns red and a huge cloud of smoke and debris rises up into the heavens, the eruptions around Penghu were much smaller. The effect was rather more like liquid flowing through cracks. The lava flowed through, covering up the area all around, forming into flat or low-gradient tablelands tens of meters deep called "mesas."
相較於劇烈的火山爆發時，整座火山通紅、烈焰熊熊，塵雲高聳入天；澎湖火山岩漿的噴發，少了誇張的空中噴射，而以洪水滔滔之姿由裂隙湧出，岩漿如洪流一般覆蓋了四面八方，進而在海中堆疊成數十公尺的平緩台地，稱為「方山」。