Violent Puffs from Krakatau. #Landsat #NASA #USGS #Earth

Violent Puffs from Krakatau

Anak Krakatau maintains a mighty and sometimes menacing presence in the Sunda Strait between Java and Sumatra, with more than 50 known periods of eruptions in almost 2,000 years. The Indonesian volcano's latest burst of activity has produced numerous plumes and lava flows in 2020, including some relatively small but notable events in April.

On April 13, 2020, the Operational Land Imager (OLI) on Landsat 8 acquired this natural-color image (OLI bands 4-3-2) of the volcano as a plume towered over the peak. The natural-color image is overlaid with the infrared signature detected by OLI of what is possibly molten rock.

"The location of the plume suggests that it is volcanic in origin," said Verity Flower, a USRA volcanologist based at NASA's Goddard Space Flight Center. Flower and colleagues use the Multi-angle Imaging Spectroradiometer (MISR) sensor on NASA's Terra satellite to measure the height of volcanic plumes and to observe the shape, size, and light-absorbing properties of the particles within plumes. "On April 12, I saw a similar feature in one of the angular MISR images with a plume-like feature above the volcano summit."

Based on the color of the plume in the image above, Flower thinks it is likely composed of mostly water vapor and gas. These small, reflective particles make a plume appear white. Conversely, larger and darker ash particles tend to look gray or brown in natural-color images.

Note the darker part of the plume extending toward the north: it appears lower in altitude than the bright, billowy part of the plume directly over the peak. "It is possible the heavier ash particles emitted are staying lower in the atmosphere and are being transported to the north by near-surface winds," Flower said. "In contrast, any water and gases within the plume, which are lighter, would be transported higher and would condense rapidly in the atmosphere."

Indonesia's Center of Volcanology and Geological Hazard Mitigation (PVMBG) reported that incandescent rock had erupted onto the volcano's surface with "insignificant intensity" in the days prior to this image.

"Anak Krakatau volcano has displayed these small eruptive bursts periodically through the last few years," Flower said. "However, it can also display more destructive activity such as tsunami-triggering eruptions."

According to the April 11 statement from PVMBG, the hazards from the volcano's recent activity included fountains of lava, lava flows, and ash rain within a radius of 2 kilometers around the crater. Thinner ash rain could extend even farther from the depending on the strength of winds. Still, the alert level remained at two on a scale of one (low) to four (high).

NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen.

Comments

CREATION OF SPATIAL DATA

Spatial data creation is the process of generating, organizing, and managing geographically referenced information in a Geographic Information System (GIS). It involves converting maps, satellite images, GPS observations, and field survey data into digital datasets that can be stored, analyzed, and visualized. The quality of GIS analysis depends largely on the accuracy of spatial data creation. 1. Creation of Shapefile and Geodatabase A. Shapefile A Shapefile is one of the most widely used vector data formats developed by Esri for storing geographic features. Definition A shapefile stores the geometry and attributes of geographic features such as points, lines, and polygons. Components of a Shapefile A shapefile consists of several files: .shp – Stores geometry (shape) .shx – Shape index .dbf – Attribute table .prj – Coordinate Reference System (CRS) .sbn/.sbx – Spatial index (optional) Geometry Types Point – W...

Geography of Health or Medical Geography

Health Geography (also known as Medical Geography ) is a sub-discipline of Human Geography that studies the relationships between place, environment, society, and health . It examines how spatial location, environmental conditions, and social and economic factors influence human health, disease patterns, and access to healthcare services. Health geography integrates concepts from geography, epidemiology, medicine, public health, environmental science, sociology, and Geographic Information Systems (GIS) to understand and improve population health. Major Components of Health Geography Health geography is generally divided into two major branches : The Geography of Disease and Ill Health The Geography of Health Care 1. The Geography of Disease and Ill Health This branch studies the spatial distribution, determinants, and diffusion of diseases across different geographical scales, from neighborhoods to global regions. It seeks t...

Nature and Scope of Geography

Geography is the scientific study of the Earth's surface, its physical features, human populations, and the interactions between people and their environment. The word Geography is derived from the Greek words Geo (Earth) and Graphien (to describe or write), meaning "description of the Earth." Modern geography goes far beyond description; it seeks to explain where phenomena occur, why they occur there, how they are spatially distributed, and how they change over time. Geography is regarded as a spatial science , an environmental science , and an integrative discipline because it bridges natural sciences, social sciences, and geospatial technologies. Nature The nature of geography refers to the characteristics and fundamental features that define the discipline. 1. Geography as a Spatial Science Terminology: Spatial Science A discipline concerned with the location, distribution, arrangement, organization, and interaction of phenomena in ...

Historical Development of Geography in the Ancient Period

The Ancient Period marks the earliest stage in the evolution of geographical thought, extending from approximately 3000 BCE to the 5th century CE . During this period, geography evolved from simple descriptions of the Earth's surface to systematic scientific inquiry. Early civilizations developed geographical knowledge to meet practical needs such as navigation, trade, agriculture, military expansion, taxation, and administration . The greatest contributions came from the Mesopotamian, Egyptian, Indian, Chinese, Greek, and Roman civilizations , with the Greeks laying the foundations of scientific geography . Meaning Terminology: Historical Development Historical development refers to the gradual evolution of geographical knowledge, concepts, methods, and theories over time. Concept Geographical knowledge evolved through: Observation of the natural environment Exploration and travel Cartography (map-making) Astronomical observations ...

Development of Health Geography

Health Geography (formerly Medical Geography ) is the branch of geography that studies the relationship between health, disease, environment, place, and healthcare systems . The discipline has evolved over more than 2,500 years through contributions from physicians, geographers, epidemiologists, microbiologists, and public health experts. The development of Health Geography can be divided into the following periods: Ancient Period Medieval Period Renaissance and Pre-Modern Period Nineteenth Century (Pre-World War Era) World War Period Post-World War Period Modern Health Geography 1. Ancient Period (5th Century BC – 500 AD) Characteristics Health closely linked with the natural environment. Diseases explained through climate, water, air, and seasons. No knowledge of microorganisms. Medical observations were descriptive. Major Concepts Environmental Determinism Disease Ecology Climate and Healt...

Vineesh V, Geography

Search This Blog