Volcanoes erupting

Volcanoes are commonly conical hills or mountains built around a vent that connect with reservoirs of molten rock below the surface of the earth. Unlike other mountains, which are pushed up from below, volcanoes are built by surface accumulation of their eruptive products—layers of lava flows, ash flows, and ash. When pressure from gases within the molten rock becomes too great, gases drive the molten rock to the surface and an eruption occurs.

Volcanic eruptions can inject into the stratosphere tens of teragrams of chemically and microphysically active gases and solid aerosol particles that can affect the Earth’s radiative balance and climate and disturb the stratospheric chemical equilibrium.People have died from volcanic blasts. The most common cause of death from a volcano is suffocation. Volcanic eruptions can result in additional threats to health, such as floods, mudslides, power outages, drinking water contamination, and wildfires.
Volcanic eruptions can be placed into two general categories:those that are explosive, such as the 1980 eruption of Mount St. Helens, and those that are effusive, such as the gentle lava flows, fountains, and spatter cones common in Hawai'i. Many eruptions are explosive in nature.They produce fragmented rocks from erupting lava and surrounding parent rock.Non explosive eruptions are favored by low gas content and low viscosity magmas (basaltic to andesitic magmas).
Explosive eruptions are favored by high gas content and high viscosity (andesitic to rhyolitic magmas).
The major component of volcanic eruptions is magmatic material, which emerges as solid, lithic material or solidifies into large particles that are referred to as ash or tephra.Volcanic eruptions typically also emit gases, with water (H2O), nitrogen (N2) and carbon dioxide (CO2) being the most abundant.Most gases from a volcano quickly blow away. However, heavy gases such as carbon dioxide and hydrogen sulfide can collect in low-lying areas.