Strombolian Eruptions: Basaltic Magma Explosions

• Strombolian eruptions are moderate explosions of relatively fluid basaltic magma.
• They are named after the Stromboli volcano in Italy, which is known for its frequent, predictable eruptions.
• These eruptions are characterized by discrete bursts of gas that propel clots of lava into the air in a rhythmic fashion.
• Strombolian eruptions typically involve tephra such as bombs and lapilli.
• Lava flows may also be produced, though they are generally not extensive.
• The explosions are caused by the bursting of large gas bubbles at the summit vent.
• Strombolian eruptions are generally of low to moderate intensity.
• They are among the mildest types of explosive volcanic eruptions.
• These eruptions pose less of a hazard compared to other, more violent eruption types.
• Strombolian eruptions are often associated with open-system volcanoes, where magma is constantly present in the conduit.
• Typical eruption column heights range from tens to hundreds of meters.
• Eruptions can last from minutes to days or even weeks.

Vulcanian Eruption

• Vulcanian eruptions are short, violent, explosive events.
• They are named after the Italian island of Vulcano.
• These eruptions are characterized by the ejection of pyroclastic rocks, ash, and gas.
• Vulcanian eruptions often start with the clearing of a solidified plug of lava from the volcanic conduit.
• The explosions are caused by the buildup of gas pressure beneath this plug.
• Vulcanian eruptions can eject material at supersonic speeds.
• The ash columns can reach heights of several kilometers.
• These eruptions are generally more explosive than Strombolian eruptions.
• They are less sustained than Plinian eruptions.
• Vulcanian eruptions are dangerous due to the potential for pyroclastic flows and surges.
• These eruptions can occur at a variety of volcano types.
• They can be a precursor to larger, more explosive eruptions.
• Vulcanian eruptions often produce cauliflower-shaped ash clouds.
• The duration of a Vulcanian eruption is typically short, lasting from a few minutes to a few hours.

Pelean Eruption

• Pelean eruptions are characterized by the occurrence of pyroclastic flows.
• They are named after Mount Pelée on the island of Martinique, where a devastating eruption occurred in 1902.
• These eruptions are associated with viscous magma that tends to form lava domes.
• The lava dome can collapse, generating pyroclastic flows that move rapidly down the volcano's slopes.
• Pelean eruptions are among the most dangerous types of volcanic eruptions.
• Pyroclastic flows are hot, fast-moving currents of gas and volcanic debris.
• These flows can destroy everything in their path.
• Pelean eruptions are often accompanied by powerful explosions.
• They can generate ash clouds that reach high into the atmosphere.
• The 1902 eruption of Mount Pelée destroyed the city of Saint-Pierre.
• More than 30,000 people were killed.
• Pelean eruptions typically occur at stratovolcanoes.
• These volcanoes have steep slopes and are prone to dome collapse.
• The eruption column is often small compared to Plinian eruptions, but the pyroclastic flows are the main hazard.

Hawaiian Eruption

• Hawaiian eruptions are characterized by the effusive emission of basaltic lava.
• They are named after the volcanoes of Hawaiʻi.
• These eruptions are typically non-explosive.
• Lava flows are the primary volcanic hazard.
• Hawaiian eruptions often produce lava fountains.
• Fountains are caused by the release of gas from the lava.
• The fountains can reach heights of several hundred meters.
• Hawaiian eruptions can also produce lava lakes.
• Lava lakes are pools of molten lava that accumulate in craters or depressions.
• These eruptions can build shield volcanoes.
• Shield volcanoes are broad, gently sloping volcanoes formed by the accumulation of lava flows.
• Hawaiian eruptions are generally less dangerous than other types of eruptions.
• The lava flows move relatively slowly, allowing people to evacuate.
• However, lava flows can still cause significant property damage.
• Vog (volcanic smog) is a common byproduct of Hawaiian eruptions.
• Vog is a mixture of volcanic gases and fine particles.
• It can cause respiratory problems.

Phreatic Eruption

• Phreatic eruptions are steam-driven explosions.
• They occur when magma heats ground water or surface water.
• The water flashes to steam, creating an explosion.
• Phreatic eruptions do not involve the direct eruption of magma.
• They primarily eject steam, hot water, ash, and rock fragments.
• Phreatic eruptions can occur with little or no warning.
• They can be dangerous because they can be unexpected.
• These eruptions can occur in volcanic areas or geothermal areas.
• Phreatic eruptions can create explosion craters.
• These craters are often shallow and wide.
• Phreatic eruptions can trigger lahars (mudflows).
• Lahars are a mixture of volcanic ash, rock, and water.
• They can travel long distances and cause significant damage.
• Phreatic eruptions are typically short-lived.
• They can be a precursor to more significant volcanic activity.
• The eruption column is often composed mainly of steam, making it appear white.