Today in our geology lecture, we're discussing volcanic activity. One key point is that volcanoes are not all the same. For example, shield volcanoes, like those in Hawaii, have gentle slopes and erupt fluid lava continuously. In contrast, stratovolcanoes, such as Mount Fuji, are taller and more cone-shaped, with explosive eruptions. The type of eruption depends on the lava's viscosity, which is influenced by its silica content. High silica lava traps gas, leading to violent explosions. Low silica lava flows more easily. Also, volcanic hazards include not just lava flows but also ash clouds, which can affect air travel and climate. Remember, the most destructive eruptions are often those with high silica.