John Q's Geology 9 Blog

  Figure 1: The Anak Krakatau volcano, infamous for its extreme eruptions is seen here launching lava bombs and generating its own lightning during its eruption on October 25, 2018.      Indonesia is a volcanically active country, and is home to numerous major volcanoes.  It has the most volcanoes of any country in the world, with 76 volcanoes that have erupted at least 1,171 times in total within historical times.  The Smithsonian Institution has 141 entries in its volcano database.  Indonesia has around 130 active volcanoes that are part of the Pacific Ring of Fire, and it has suffered the highest numbers of eruptions resulting in fatalities, damage to arable land, debris flows, tsunamis, lava domes, and pyroclastic flows.  Indonesia's most active volcanoes are Kelut and Mount Merapi on the island of Java.  The majority of Indonesia's volcano are located on a 5,000 km long chain called the Sunda Arc.  Here, the heavy oceanic Indo-Australian Plate subducts beneath the continen

       Indonesia's Earthquakes Earthquake Risks in Indonesia Indonesia's geographical location along the boundaries of four major tectonic plates namely the Eurasian, Indo-Australian, Pacific and Philippine Sea plates accounts for the restive seismic activity in the region.    The map below illustrates the earthquake risk zone map of Indonesia.  The risk increases from a minimum risk (Zone I) to a maximum risk (Zone V). Earthquake Intensity The map below shows the countless earthquakes that struck Indonesia since the start of the 20th century.   These seismic activities in Indonesia and the surrounding area provides crucial evidence for the active tectonic processes of this region.  The bigger the circle, the higher the magnitude of the earthquake in the Richter Scale.  The lone black circle represents the most destructive earthquake, the indian Ocean Earthquake of 2004, that devastated the country in its modern history. Indonesia's Active Faults The known principal zones o