Landslides, also known as landslips, or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides.
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding. Examples for human changes are land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees. Global environmental issues also influence causes of floods, namely climate change which causes an intensification of the water cycle and sea level rise. For example, climate change makes extreme weather events more frequent and stronger. This leads to more intense floods and increased flood risk.
A natural disaster is the very harmful impact on a society or community after a natural hazard event. Some examples of natural hazard events include avalanches, droughts, earthquakes, floods, heat waves, landslides, tropical cyclones, volcanic activity and wildfires. Additional natural hazards include blizzards, dust storms, firestorms, hails, ice storms, sinkholes, thunderstorms, tornadoes and tsunamis. A natural disaster can cause loss of life or damage property. It typically causes economic damage. How bad the damage is depends on how well people are prepared for disasters and how strong the buildings, roads, and other structures are. Scholars have been saying that the term natural disaster is unsuitable and should be abandoned. Instead, the simpler term disaster could be used. At the same time the type of hazard would be specified. A disaster happens when a natural or human-made hazard impacts a vulnerable community. It results from the combination of the hazard and the exposure of a vulnerable society.
A lahar is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley.
Atami is a city located in Shizuoka Prefecture, Japan. As of 1 May 2019, the city had an estimated population of 36,865 in 21,593 households and a population density of 600 persons per km2. The total area of the city is 61.78 square kilometres (23.85 sq mi).
A geologic hazard or geohazard is an adverse geologic condition capable of causing widespread damage or loss of property and life. These hazards are geological and environmental conditions and involve long-term or short-term geological processes. Geohazards can be relatively small features, but they can also attain huge dimensions and affect local and regional socio-economics to a large extent.
Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep, solifluction, rockfalls, debris flows, and landslides, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth, Mars, Venus, Jupiter's moon Io, and on many other bodies in the Solar System.
A mudflow, also known as mudslide or mud flow, is a form of mass wasting involving fast-moving flow of debris and dirt that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/second. Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows, allowing them to travel farther and across lower slope angles. Both types of flow are generally mixtures of particles with a wide range of sizes, which typically become sorted by size upon deposition.
The Vargas tragedy was a natural disaster that occurred in Vargas State, Venezuela on 15 December 1999, when torrential rains caused flash floods and debris flows that killed tens of thousands of people, destroyed thousands of homes, and led to the complete collapse of the state's infrastructure. According to relief workers, the neighborhood of Los Corales was buried under 3 metres (9.8 ft) of mud and a high percentage of homes were simply swept into the ocean. Entire towns including Cerro Grande and Carmen de Uria completely disappeared. As much as 10% of the population of Vargas died during the event.
The Mandakini River is a tributary of the Alaknanda River in the Indian state of Uttarakhand. The river runs for approximately 81 kilometres (50 mi) between the Rudraprayag and Sonprayag areas and emerges from the Chorabari Glacier. The Mandakini merges with river Songanga at Sonprayag and flows past the Hindu temple Madhyamaheshwar at Ukhimath. At the end of its course it drains into the Alaknanda, which flows into the Ganges.
There have been known various classifications of landslides. Broad definitions include forms of mass movement that narrower definitions exclude. For example, the McGraw-Hill Encyclopedia of Science and Technology distinguishes the following types of landslides:
An earthflow is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity. It is an intermediate type of mass wasting that is between downhill creep and mudflow. The types of materials that are susceptible to earthflows are clay, fine sand and silt, and fine-grained pyroclastic material.
Wildfires are outdoor fires that occur in the wilderness or other vast spaces. Other common names associated with wildfires are brushfire and forest fire. Since wildfires can occur anywhere on the planet, except for Antarctica, they pose a threat to civilizations and wildlife alike. In terms of emergency management, wildfires can be particularly devastating. Given their ability to destroy large areas of entire ecosystems, there must be a contingency plan in effect to be as prepared as possible in case of a wildfire and to be adequately prepared to handle the aftermath of one as well.
On 20 August 2014, Hiroshima Prefecture in Japan was struck by a series of landslides following heavy rain. The rain triggered 166 slope failures which included 107 debris flows and 59 shallow slides. The landslides hit residential areas including Kabe, Asakita Ward, Yagi, Yamamoto, Midorii, and Asaminami Ward. Of these areas, the Asakita and Asaminami Wards in Northern Hiroshima were hit the hardest.
Zimbabwe experienced severe floods from December 2016 through March 2017 due to heavy rains that followed a two-year drought.
Climate change is having serious impacts in the Philippines such as increased frequency and severity of natural disasters, sea level rise, extreme rainfall, resource shortages, and environmental degradation. All of these impacts together have greatly affected the Philippines' agriculture, water, infrastructure, human health, and coastal ecosystems and they are projected to continue having devastating damages to the economy and society of the Philippines.
During the heavy rainfall over the monsoon period from 1 June to 18 August 2020, all 14 districts in Kerala were affected with 104 dead and 40 injured. Four districts in Kerala were flooded on 7 August 2020. Major reported incidents in relation to flooding include a landslide in Idukki district on 6 August, claiming 66 lives and an Air India plane crash that caused the death of 21 people. The 2020 flood in Kerala marked the third year in a row of severe monsoon flooding.
Urban flooding is the inundation of land or property in cities or other built environment, caused by rainfall or coastal storm surges overwhelming the capacity of drainage systems, such as storm sewers. Urban flooding can occur regardless of whether or not affected communities are located within designated floodplains or near any body of water. It is triggered for example by an overflow of rivers and lakes, flash flooding or snowmelt. During the flood, stormwater or water released from damaged water mains may accumulate on property and in public rights-of-way. It can seep through building walls and floors, or backup into buildings through sewer pipes, cellars, toilets and sinks.
In 2016 Pakistan experienced higher rainfall than normal (10-20%), especially in the pre-monsoon season. Heavy monsoon rains are common in the region. This led to multiple periods of flooding, landslides, and damage particularly in Northern Pakistan. The Swat River overflowed and multiple landslides occurred around Pakistan including in Khyber Pakhtunkhwa, Gilgit-Baltistan, Azad Jammu, and Kashmir.
From January 31 to February 1, 2022, heavy rainfall impacted Ecuador, which caused multiple landslides, floods, and mudflows. It was caused by the country's biggest rainfall in nearly 20 years, which fell on the capital.
