VOLCANIC ERUPTIONS- 5 ITEMS-ASSESSMENT

JAKARTA, Indonesia (AP) — Indonesia’s highest volcano on its most densely populated island released searing gas clouds and rivers of lava Sunday in its latest eruption. Monsoon rains eroded and finally collapsed the lava dome atop 3,676-meter (12,060-foot) Mount Semeru, causing the eruption, according to National Disaster Management Agency spokesperson Abdul Muhari. Several villages were blanketed with falling ash, blocking out the sun, but no casualties have been reported. Several hundred residents, their faces smeared with volcanic dust and rain, fled to temporary shelters or left for other safe areas. Thick columns of ash were blasted more than 1,500 meters (nearly 5,000 feet) into the sky while searing gas and lava flowed down Semeru’s slopes toward a nearby river. Increased activities of the volcano on Sunday afternoon prompted authorities to widen the danger zone to 8 kilometers (5 miles) from the crater, said Hendra Gunawan, who heads the Volcanology and Geological Hazard Mitigation Center. He said scientists raised the volcano’s alert level to the highest and people were advised to keep off the southeastern sector along the Besuk Kobokan River, which is in the path of the lava flow. Semeru’s last major eruption was in December last year, when it blew up with fury that left 51 people dead in villages that were buried in layers of mud. Several hundred others suffered serious burns and the eruption forced the evacuation of more than 10,000 people. The government moved about 2,970 houses out of the danger zone. Semeru, also known as Mahameru, has erupted numerous times in the past 200 years. Still, as is the case with many of the 129 active volcanoes in Indonesia, tens of thousands of people continue to live on its fertile slopes. Indonesia, an archipelago of more than 270 million people, sits along the Pacific “Ring of Fire,” a horseshoe-shaped series of fault lines, and is prone to earthquakes and volcanic activity.

3. Volcanoes are often found at meeting points of “tectonic plates”. These plates are pieces of the Earth’s surface that fit together just like a jigsaw puzzle. 4. Volcanoes can also occur over “mantle plumes”. Ever heard of mantle plumes? They’re super-hot areas of rock inside the Earth! Did you know that we have a FREE downloadable Volcanoes of Ecuador primary resource? Great for teachers, homeschoolers and parents alike! 5. Approximately 350 million people live within “danger range” of an active volcano. That means that around one in 20 people live in an area at risk of volcanic activity. Volcano facts 6. Volcanoes are classified as active, dormant or extinct. This refers to the amount of volcanic activity. “Active” means there’s regular activity, “dormant” means there’s been recent activity but the volcano is currently quiet, and “extinct” means it’s been so long since the last eruption that it’s unlikely to ever erupt again. 7. Volcanoes can be a variety of shapes. These geographical wonders come in various shapes and sizes, but there are two main types – composite volcanoes, which are cone-shaped with steep slopes, and shield volcanoes, which are wide with gentle slopes. 8. Magma and lava are two different things! Magma is the name given to hot liquid rock inside a volcano. Once it leaves the volcano, it’s known as lava. Psst! Make sure you download our awesome volcano facts infographic – show your friends, family, or stick it on your wall!

Volcanic Eruptions Earthquakes are sometimes used in predicting volcanic eruptions. An earthquake alerts the authorities to observe a nearby volcano. When a volcano shows signs of eruption, evacuation of the nearby villages should be immediately implemented Active volcanoes are the ones that are usually closely monitored by volcanologists These are commonly located along plate boundaries specifically along the Pacific Ring of Fire. The Philippines is one of the countries that have a lot of volcanoes. The Pacific Ring of Fire is a region in the Pacific where most active volcanoes are located. The dots in the figure represent the active volcanoes in the world. Active volcanoes are those that have a recorded volcanic eruption in their history. There are two types of volcanic eruptions depending on the magma composition: the explosive type and the Hawaiian or nonexplosive type. The types of eruptions depend on the viscosity and amount of dissolved gases in a magma. Explosive eruptions have magma that is highly viscous and contains large amounts of dissolved gases. On the other hand, the Hawaiian type or nonexplosive eruptions have magma that has low viscosity and low amount of dissolved gases. Viscosity determines the ability of magma to flow. The lower the viscosity, the easier it is for the magma to flow. This viscosity of the magma is affected by silica content and temperature. Low-temperature magma with high silica content are highly viscous, high-temperature magma with low silica content has low viscosity. Therefore, in explosive eruptions, the magma could not easily get out of the vent. This impedes the remaining magma below, causing an increase of pressure. Once the pressure is released. an explosive eruption occurs. Volcanic Hazards Explosive volcanic eruptions release pyroclastic flows and materials that are considered to pose the greatest threat. The pyroclastic flows often render people in a shock state since they become overwhelmed with what they are seeing Too much pyroclastic material (eg., tephra), may bury people and severely damage the agricultural land and livestock. Damaged agricultural land could lead to famine. After an eruption, pyroclastic materials that have settled along the slope of the volcano get mixed with rainwater. This would start a mudflow or lahar moving at high speed, destroying everything along its path. Poisonous gases are also released by volcanoes. These gases can be lethal to people, animals, and plants. Just like earthquakes, violent volcanic eruptions may also happen underwater, which can trigger a tsunami.

Predicting volcanic eruptions

Effects of Volcanic Eruptions

Factors of Volcanic Eruptions

SCIENCE 6 - Q4 – M1: EARTHQUAKES AND VOLCANIC ERUPTIONS

The effects of earthquake and volcanic eruptions

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