Meanwhile, extreme wet or dry seasons (El Nino or La Nina weather phenomenons) can ruin food crop harvests, trigger inflation and put severe financial pressure on the poorer segments of the Indonesian population. Lastly, man-made natural disasters (such as forest fires caused by the traditional slash-and-burn culture, particularly on the islands Sumatra and Kalimantan) have far-reaching environmental consequences.

One important remark is that the weak conditions of some of its infrastructure and property - which can be the result of mismanagement, too limited financial resources, the lack of skills or corruption - in fact aggravates the devastating impact of a natural disaster. Meanwhile, in the urban centers of Indonesia, particularly the bigger cities such as Jakarta, Surabaya, Medan and Yogyakarta, there is an extremely high population density. The weak state of infrastructure and property in combination with the high population density imply that natural disasters in Indonesia may cause more casualties than they should because it will require smaller force to make a building collapse.

Volcanic Eruptions in Indonesia

Indonesia is the country that contains the most active volcanoes of all countries in the world. The Eurasian Plate, Pacific Plate and Indo-Australian Plate are three active tectonic plates that cause the subduction zones that form these volcanoes. Indonesia is estimated to have 129 volcanoes, all carefully observed by the Centre of Volcanology and Geological Hazard Mitigation (Pusat Vulkanologi dan Mitigasi Bencana Geologi), because a number of Indonesian volcanoes show continuous activity. Moreover, it is estimated more than five million people are living (and/or working) within the "danger zone" of a volcano (who need to be evacuated immediately in case of significantly rising activity).

There is at least one significant volcano eruption in Indonesia every year. However, usually it does not cause great damage to the environment or cause casualties as most of the active volcanoes are located in isolated regions.

Some notable volcanic eruptions in Indonesia's modern history are listed below. This list only contains major eruptions that led to at least 20 fatalities.

Volcano Location Date of Eruption Casualties
Merapi Central Java 03 November 2010       138
Kelut East Java 10 February 1990        35
Galunggung West Java 05 April 1982        68
Merapi Central Java 06 October 1972        29
Kelut East Java 26 April 1966       212
Agung Bali 17 March 1963     1,148
Merapi Central Java 25 November 1930     1,369
Kelut East Java 19 May 1919     5,110
Awu North Sulawesi 07 June 1892     1,532
Krakatau Sunda Strait 26 August 1883    36,600
Galunggung West Java 08 October 1822     4,011
Tambora Sumbawa 10 April 1815    71,000+

The table above shows Indonesia is rocked by a major volcanic eruption (meaning one that takes a significant number of lives), on average, once every 15-20 years.

Besides taking human lives, a volcanic eruption can cause considerable damage to local economies by hurting small and medium enterprises that are involved in tourism, culinary, commercial accommodation, agriculture, plantation, and livestock.

See map of major volcanoes in Indonesia

A positive development is that volcano eruptions take less human lives today (than in the past) due to better volcano observation methods in combination with better organized emergency evacuations. However, considering Indonesia's Centre of Volcanology and Geological Hazard Mitigation carefully monitors activity of the volcanoes and immediately warns authorities and local communities when a volcano shows a dangerously rising level of activity, one would think the number of casualties should actually be very low as people have plenty of time to leave the area (contrary to an earthquake, a volcanic eruption does not strike suddenly and gives plenty of warning signs before it becomes a life threatening disaster).

The problem is that there are plenty of local residents who simply refuse to leave their homes (that are located within the danger zone). This refusal can be related to their livelihood (their farms - their only source of income - are located within the danger zone). But it can also be related to animist believe-systems (the volcano's warning signs - such as ash and thunder - are considered to be acts of their angry ancestors, and by praying to the local gods local communities believe they will be protected from any danger).

Earthquakes in Indonesia

Earthquakes are probably the biggest threat in terms of natural disasters in Indonesia as they come suddenly and can strike in populous areas, such as the bigger cities. Earthquakes with a magnitude of around five or six on the scale of Richter occur almost on a daily basis in Indonesia but usually cause no, or little, damage. When the magnitude of the quake becomes more than seven on the scale of Richter, an earthquake can potentially do a lot of damage. On average, Indonesia experiences about one earthquake per year with a magnitude of seven, or higher, that causes casualties as well as damage to the infrastructure or environment. Below is a selected list with recent earthquakes that caused severe damage and at least 20 fatalities:

Location Date Magnitude Casualties
Sumatra 07 December 2016       6.5       104
Sumatra 02 July 2013       6.1        42
Sumatra 25 October 2010       7.7       435
Sumatra 30 September 2009       7.6     1,117
Java 02 September 2009       7.0        81
Sumatra 12 September 2007       8.5        23
Sumatra 06 March 2007       6.4        68
Java 17 July 2006       7.7       668
Java 26 May 2006       6.4     5,780
Sumatra 28 March 2005       8.6     1,346
Sumatra 26 December 2004       9.2    283,106

Earthquakes form a constant threat in Indonesia due to the meeting of major tectonic plates and volcanic activity in the region. Some earth scientists are currently waiting for the next "great earthquake" in Indonesia due to the building up of stress on one of the earth's great plate boundaries to the west of Sumatra (the collision between the Indian ocean plate and the Asian plate), similar to the disastrous 9.2 magnitude earthquake that occurred on 26 December 2004 and caused a devastating tsunami (read more below). However, scientists do not know when, or where, this next big earthquake will happen.

See map of tectonic plates that make up the Ring of Fire

The high number of Indonesian casualties involved in a big quake is partly inflicted by the bad state of some housing facilities and infrastructure. This is why a moderate earthquake can in fact result in many casualties, the collapse of many buildings and the displacement of many people. A World Bank publication (in October 2010) expressed its concern about the devastating effects an 8.5 magnitude earthquake can have if it would happen in a mega-city such as Jakarta.

Tsunamis in Indonesia

A submarine earthquake or volcanic eruption in the ocean can cause a tsunami water wave which can have devastating effects on the people and objects near the sea. In 2004 a large part of the world was rocked by the Indian Ocean earthquake and subsequent tsunami, killing over 167,000 people in Indonesia (mainly Aceh) alone and resulted in the displacement of more than half a million of people as thousands of homes were wiped away. Although a massive tsunami such as the 2004 tsunami is rare, the Sumatra region is often startled by offshore earthquakes that can potentially trigger a tsunami.

With the 2004 tsunami still fresh in mind, the level of fear is high. Often Indonesians who live in villages or cities close to the coast, flee to the hills (located more inland) after an earthquake has taken place as they are afraid of becoming victim of a tsunami (although it is usually false alarm). On average, once every five years a large tsunami happens in Indonesia, mostly on the islands of Sumatra and Java. In general, damage done to the infrastructure exceeds the loss of lives. There are warning systems installed on many coastal areas but there have been reports that not all of these systems are functioning properly.

Floods in Indonesia

Indonesia's rainy season (which runs from December to March) usually brings plenty of rainfall. In combination with deforestation or waterways clogged with debris, it can cause rivers to overflow and this results in floods. Floods and landslides occur in most parts of Indonesia and can cause hundreds of casualties, destroy houses and other infrastructure, and ruin local businesses. Even in a mega-city as Jakarta, floods occur regularly (basically every year) due to weak water management in combination with heavy monsoon rains. In January 2013, a large part of Jakarta was flooded, affecting more than 100.000 households and resulting in more than 20 fatalities. Also in February 2017 Jakarta was plagued by big floods causing thousands of homes being flooded by murky brown water, sometimes as deep as 1.5 meters.

In the rainy season floods usually disturb the distribution channels and therefore Indonesia tends to experience some rising inflationary pressures during the months January and February when the monsoon rains tend to peak. Wet conditions can be aggravated by the La Nina weather phenomenon. La Nina (basically the opposite of El Nino), a phenomenon that occurs once every five years on average, brings cooler-than-average sea temperatures in the central and eastern tropical Pacific Ocean. It therefore causes wetter-than-usual weather in Southeast Asia, usually in the months November to February.

Man-Made Forest Fires in Indonesia

Generally Indonesians have a low awareness of environmental sustainable practices. This is reflected by farmers' and companies' use of slash-and-burn practices (a strategy to clear land for plantations, usually for the expansion of crude palm oil or pulp and paper plantations), primarily on the islands of Sumatra and Kalimantan. The slash-and-burn strategy is the cheapest option and is therefore frequently used. Although this practice is actually not allowed by Indonesian law, weak law enforcement and corruption make it possible. However, the practice entails serious and far-reaching risks.

For example, forest fires in the months June-October 2015 ran out of hand completely. Based on a World Bank report - released in December 2015 - some 100,000 man-made forest fires destroyed about 2.6 million hectares of land on Kalimantan and Sumatra between June and October 2015. It also caused toxic haze to spread to other parts of Southeast Asia, giving rise to diplomatic tensions. This disaster is estimated to have cost Indonesia IDR 221 trillion (approx. USD $16 billion or 1.9 percent of the country's gross domestic product) and it released some 11.3 million tons of carbon each day (a figure that exceeds the 8.9 million tons of daily carbon emissions in the European Union), thus being one of the worst ever natural disasters in human history.

The forest fires in 2015 ran out of hand partly because of unusual dry weather. The El Nino weather phenomenon, the strongest one since 1997, brought severe dry weather to Southeast Asia and therefore firefighters could not count on support from rain. El Nino, which occurs once every five years on average, causes climatic changes across the Pacific Ocean leading to droughts in Southeast Asia and therefore also has a major impact on harvests of agricultural commodities.

Last update: 23 June 2017