Day_205 : The story of a massive landslide that occasionally triggered a massive tsunami: The 1970 Peru earthquake and the 1984 Mount Ontake landslide

In 1970, a major earthquake (magnitude 7.7) in Peru caused a massive collapse of the summit of Mount Huascaran in the Andes. The large amount of rock and ice (about 100 million cubic metres) that fell from the mountain flowed down for about 14.5 kilometres at more than 300 kilometres per hour. This flow over a 230-meter-high ridge covered the town of Yungai, with a population of 25,000, in a 5-meter-thick layer, killing around 15,000 people.

Meanwhile, in Japan, a 6.8-magnitude earthquake in 1984 in western Nagano Prefecture caused the collapse of some 36 million cubic metres of earth and rock at Kiso-Ontake; in 1792, Mount Unzen-Mayuma probably collapsed in an earthquake, causing some 340 million cubic metres of rock to collapse and flow into the Ariake Sea, causing a tsunami of up to 23 metres.

In an ordinary landslide, the coefficient of friction that indicates the distance and speed at which rocks and soil move is around 0.5, but in a particularly large debris avalanche, this can drop to 0.1 and move much further and faster. Large volcanoes are more prone to such large landslides because of the instability of their internal structure.



Day_87 : North and Central Americas – Mt. St.Helens and Mt.Pelee

1.Volcanic Disasters

North America
Mount St.Helens erupted in 1980. 57 people were dead.
St.Helens volcanic eruption was really huge. You can see this from the following video.


From environmental and sociological perspectives, the difference between the U.S. and Japan is the people’s and nature’s relationships. This case indicated that somehow. The people are living far from nature, on Mt.Helens. That is why the fatality number was not so large compared to the huge eruption. In Japan, people tend to live near and with nature. This is called “Satoyama” in Japanese. Other Asian countries are the same with Japan.
This will be discussed later.

Mount Pelee
St.Pierre City was destroyed completely in 1902 by Mt. Plee’s eruption.
The population of the city was approx. 28000; almost all were dead, only 2 survived. One of the only two survivors was in prison. The story can be seen from the following video.

2. Climate, meteorological, and hydrological disasters: Hurricanes

North America
In 1900, Galveston’s death toll was over 6,000
2005 Katrina, the death toll was over 1400, and the cost was $100 billion . UDS
In 1998, Mitch reported that 13,700 people were victimized in Honduras and 3,300 in Nicaragua
Hurricane Jeanne,  2800 were killed in Haiti

Disaster data, such as death toll, is sourced from the NIED DIL homepage.

Day_138 : Natural Disasters in Europe (1)

Natural disasters in Europe mainly consist of hydrological, meteorological, climatological, earthquake and volcano eruption disasters.

Figure   The Europe

Earthquake disasters mainly occur in the Aegean Sea, the south-western coast of Balkan Peninsula, and the southern part of Italy. Volcanoes are active in the central and southern parts of Italy, the southern Aegean Sea, and Iceland area.

Concerning hydrological, meteorological, and climatological disasters, heavy rain and storm disasters are caused by low  pressure in the Icelandic area developed in the winter season. A cold atmospheric current coming from Arctic gains a warmer vapor stream from the Gulf Stream and develops a strong atmospheric depression in the area. This causes the strong winds and high tidal waves along the coastal areas of the North Sea.

Netherlands and England can be highlighted. The Netherlands had storm surges in 1530 and 1570. The death tolls were approximately 400,000 (1530) and 70,000 (1570) for each. The 1953 depression took an 1800-person death toll. This disaster also reached England. England’s disasters were the 1703 Thames river flood and the 2003 Heatwave. The temperature was 8–10 over the average year in August 2003.

With regard to earthquake disasters, Italy, Greece, and Portugal are the main countries to be affected.

The following past article explains the recent earthquake cases in Italy.

To be continued…

Day_183: Introduction of Understanding Earthquakes

Earthquakes, being a natural phenomena, have generated both attraction and fear among people worldwide. We are aware of earthquakes leading to enormous devastation, fatalities, property damage, and potentially initiating tsunamis. Despite the numerous technological developments, earthquakes remain unpredictable and have the potential to occur at any given moment and location.

An earthquake is the result of a sudden slip between two blocks of the earth’s crust, which leads to the release of energy in the form of seismic waves. Seismic waves propagate through the Earth’s crust and can be monitored by devices known as seismometers. Earthquakes occur in various regions of the planet, encompassing terrestrial areas, subaquatic environments, and even within the earth’s mantle. The seismic intensity of an earthquake is quantified using the Richter scale, which spans from 1 to 10.

Earthquakes result from a multitude of sources, encompassing tectonic plate displacement, volcanic eruptions, and even anthropogenic operations like mining and drilling.

Day_114 : World Disaster Chronology-1980


Date Place Disaster Type Situations
1980.01- US, East Cold Wave 100 (DM)
1980.01- India, North Cold Wave 80 (DM) Bihar 
1980.04- Peru Heavy Rain, Flood 90 (DM)
1980.05- US, Northwestern Volcano  Mount St.Helens Volcanic Eruption*  80 (DM), A summit was disappeared by landslide and huge volcanic eruptions.
1980.06- India Heavy Rain, Flood Over 600 (DM)
1980 India Disease Over 550 (D)
1980.07- Japan Cool weather damage Damage cost was over 6,900 mil, yen
1980.07.28 Nepal Inland Earthquake (not confirmed), 90(DM)
1980.08- Japan Heavy Rain, Flood 26 (DM),Injured 50, Destroyed 400, Inundation over 39,000
1980.08- US, East Heat Wave 1,000-1,300 (DM)
1980.08- India, East Heavy Rain, Flood Over 1,500 (DM)
1980.08- Haiti Storm, Flood 270 (DM)
1980.08- China Heavy Rain, Flood Unknown (DM)
1980 Bangladesh Heavy Rain, Flood Over 650 (DM)
1980.09- India, Southeastern Heavy Rain, Flood 200 (DM), Orrisa
1980.10.10 Algeria, Northwestern Inland Earthquake  M7.1-7.5, El Asnam Earthquake 2,600-5,000(DM)
1980.10- India Infectious disease Over 400 (D)
1980.10.24 Mexico, Central Inland Earthquake (unknown), 65 (DM)
1980.11.23 Italy, South Inland Earthquake 1980 Irpinia earthquake** M6.9   2,500-4,700 (DM)
1980.12- Japan Heavy Snow 103 (DM)Injured over 1,300, Destroyed over 5,800, Inundation over5,500

D: Dead number DM: The dead and missing number

*St.Herens volcanic eruption


**1980 Irpinia earthquake


Day_78 : Disaster statistics – Overview

The following is the overview of disasters in the World. The data 1970-2010, over 2000 death toll disasters which have 50 events, was analyzed (Total death toll approx. 3mil.).

Vulnerable Areas:
1. Southeast Asia –West Asia
Over 50% of the world pop.is living.
events 68%
death 56%
Countries : The Philippines, Indonesia, China, Myanmar, Bangladesh, India,Pakistan, Afghanistan, Iran, Armenia, Turkey

2. Central America
event 18%
death 14%
Countries: Mexico, Guatemala, Nicaragua, Honduras, Haiti, Venezuela,Columbia, Peru

3. Africa
Drought: 3event, total death toll 0.9mil. (29%)

4. By country
India 8, Iran 6, Bangladesh 4, China/Indonesia/The Philippines 3

India : Earthquake and Flood
Iran : Earthquake 1/4 of the world earthquake disasters (over 1000 death toll)
Bangladesh : Storm Surge 1/10 year has over 1000 death toll event.

5. Others
Volcanic Disaster
Indonesia : 13/30 events (over 1000 death toll after 1960s) in the world.

Affected People
Populated Countries: China and India: Flood and drought

These analyses referred the NIED DIL homepage (in Japanese).


Day_65 : 1991 Unzen Fugendake Volcano Eruption

1991 Unzen Fugendake Volcano Eruption Killed 43 people. This disaster has taught a lot of lessons. The key words are media, volunteer firefighters, police officers, and an evacuation area. The people were all dead in the evacuation area. During the volcano eruption, media people tried to get into the area to shoot pictures, videos, and report. They went into the local people’s houses. The residents were worried about their belongings in their houses. So many volunteer firefighters (12) also went into the area to check, and police officer (2) also did that. The taxi drivers (4) bring them into the area. They all died in the area. Katia Krafft and Maurice Krafft, world’s famous French volcanologists were also dead during the disaster.


Wikipedia (Katia and Maurice Krafft)

Wikipedia (Unzen Fugendake Pyroclastic flow, Japanese)

Day_64 : 1985 Nevado del Ruiz Volcano Eruption

One of the most significant volcano disaster we must know is 1985 Nevado del Ruiz volcano eruption. Approx.23000 citizens in Armero city were dead. The cultural aspects were embedded in this disaster. The disaster was predicted. The hazard maps indicated the city would be affected by the volcano eruption and lahars. The both, priest and mayor, told the citizens to stay in the same place because they were afraid of panic before the time, did not tell them to evacuate. That made tragedy. The people in the city tended to follow the both persons because of the culture, a religious and vertically‐structured society. There were also other factors*.