John Q's Geology 9 Blog

                                                                    Figure 1:  This animation illustrates the power of the sea over the land.                        (C oastal erosion at North Cove, Washington. The red line indicates the shoreline in 1990) Coastal Hazards in Indonesia Indonesia has more than 17,500 islands with a total shoreline of approximately 80,000 km. The coasts are the most dynamic areas in this Southeast Asian nation as these are very strategic locations with many natural resources for human livelihood.  Majority of the coastal population subsists on fishing and to a greater extent beach tourism.   Many large cities with dense population such as Jakarta, Semarang, Surabaya, are located in coastal areas.  Indonesia’s coastal areas have geomorphologically complex processes including coastal environmental degradation due to natural hazards (Figure 2).                                                                                       Figure 2:  Coastal dynamics, g

Disaster Risks in Indonesia The Republic of Indonesia is among the nations with the highest disaster risk in the world and ranks second behind Bangladesh on a global scale. This risk is driven by the country's high exposure to a range of geophysical and hydro-meteorological hazards.  Disasters caused by environmental hazards are becoming increasingly costly and severe in Indonesia.  The country's vulnerability to disasters is attributed to its unique geographic characteristics as an archipelago of about 17,500 islands with over 81,000 km of coastline that stretches along the equator.  The country's islands are home to an extremely varied geography, topography, and climate. Figure 1:  Proportion of disasters in Indonesia (1998-2018). Source Disaster database & information BNPB Drought In Indonesia The pie chart above represents the proportion of disasters that have hit Indonesia in the past two decades.  Though flooding remains to be the number one weather related disas

  Mass Wasting and Landslides in Indonesia A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material (bedrock, debris, or earth). Debris flows (commonly referred to as mudflows or mudslides) and rock falls are examples of common landslide types. Almost every landslide has multiple causes. Slope movement occurs when forces acting down-slope (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Causes include factors that increase the effects of down-slope forces and factors that contribute to low or reduced strength. Landslides can be initiated in slopes already on the verge of movement by ra

  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