In 1812, the caldera began to rumble and generated a dark cloud.The eruption caused a tsunami and, because of the ash and other effects, directly killed as many as 71,000. (Undoubtedly, because of larger populations and greater population densities, the death toll would be much larger today).
On 5 April 1815, a moderate-sized eruption occurred, followed by thunderous detonation sounds, heard in Makassar on Sulawesi, 380 km (240 mi) away, Batavia (now Jakarta) on Java 1,260 km (780 mi) away, and Ternate on the Molucca Islands 1,400 km (870 mi) away. On the morning of April 6, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be sound of firing guns was heard on April 10 on Sumatra island (more than 2,600 km or 1,600 mi away).
At about 7 p.m. on 10 April, the eruptions intensified. Three columns of flame rose up and merged. The whole mountain was turned into a flowing mass of "liquid fire". Pumice stones of up to 20 centimetres (7.9 in) in diameter started to rain down at approximately 8 p.m., followed by ash at around 9–10 p.m. Hot pyroclastic flows cascaded down the mountain to the sea on all sides of the peninsula, wiping out the village of Tambora. Loud explosions were heard until the next evening, 11 April. The ash veil had spread as far as West Java and South Sulawesi. A "nitrous" odour was noticeable in Batavia and heavy tephra-tinged rain fell, finally receding between 11 and 17 April.
Of particular interest to preppers was the global consequences.
The 1815 eruption released sulfur into the stratosphere, causing a global climate anomaly. Different methods have estimated the ejected sulfur mass during the eruption: the petrological method; an optical depth measurement based on anatomical observations; and the polar ice core sulfate concentration method, using cores from Greenland and Antarctica. The figures vary depending on the method, ranging from 10E6 to 120E6 tonnes (11,000,000 to 130,000,000 short tons).Wikipedia elsewhere notes:
In the spring and summer of 1815, a persistent dry fog was observed in the northeastern United States. The fog reddened and dimmed the sunlight, such that sunspots were visible to the naked eye. Neither wind nor rainfall dispersed the "fog". It was identified as a stratospheric sulfate aerosol veil. In summer 1816, countries in the Northern Hemisphere suffered extreme weather conditions, dubbed the Year Without a Summer. Average global temperatures decreased about 0.4–0.7 °C (0.7–1.3 °F), enough to cause significant agricultural problems around the globe. On 4 June 1816, frosts were reported in Connecticut, and by the following day, most of New England was gripped by the cold front. On 6 June 1816, snow fell in Albany, New York, and Dennysville, Maine. Such conditions occurred for at least three months and ruined most agricultural crops in North America. Canada experienced extreme cold during that summer. Snow 30 cm (12 in) deep accumulated near Quebec City from 6 to 10 June 1816.
1816 was the second coldest year in the northern hemisphere since 1400 CE, after 1601 following the 1600 Huaynaputina eruption in Peru. The 1810s are the coldest decade on record, a result of Tambora's 1815 eruption and other suspected eruptions somewhere between 1809 and 1810 (see sulfate concentration figure from ice core data). The surface temperature anomalies during the summer of 1816, 1817 and 1818 were −0.51 °C (−0.918 °F), −0.44 °C (−0.792 °F) and −0.29 °C (−0.522 °F), respectively. As well as a cooler summer, parts of Europe experienced a stormier winter.
This pattern of climate anomaly has been blamed for the severity of typhus epidemic in southeast Europe and the eastern Mediterranean between 1816 and 1819. The climate changes disrupted Indian monsoons causing three failed harvests and famine contributing to worldwide spread of a new strain of cholera originating in Bengal in 1816. Much livestock died in New England during the winter of 1816–1817. Cool temperatures and heavy rains resulted in failed harvests in the United Kingdom of Great Britain and Ireland. Families in Wales traveled long distances as refugees, begging for food. Famine was prevalent in north and southwest Ireland, following the failure of wheat, oat and potato harvests. The crisis was severe in Germany, where food prices rose sharply. Due to the unknown cause of the problems, demonstrations in front of grain markets and bakeries, followed by riots, arson and looting, took place in many European cities. It was the worst famine of the 19th century.
The Year Without a Summer (also known as the Poverty Year, Year There Was No Summer, and Eighteen Hundred and Froze to Death) was 1816, in which severe summer climate abnormalities caused average global temperatures to decrease by about 0.4–0.7 °C (0.7–1.3 °F), resulting in major food shortages across the Northern Hemisphere. It is believed that the anomaly was caused by a combination of a historic low in solar activity with a volcanic winter event, the latter caused by a succession of major volcanic eruptions [in the period 1812 to 1814 at various locations] capped by the 1815 eruption of Mount Tambora, in the Dutch East Indies (Indonesia), the largest known eruption in over 1,300 years.Note this concerning food prices:
In July and August, lake and river ice were observed as far south as Pennsylvania. Rapid, dramatic temperature swings were common, with temperatures sometimes reverting from normal or above-normal summer temperatures as high as 95 °F (35 °C) to near-freezing within hours. Even though farmers south of New England did succeed in bringing some crops to maturity, maize and other grain prices rose dramatically. The price of that staple food, oats, for example, rose from 12¢ a bushel ($3.40/m³) in 1815, equal to $1.52 in today's purchasing power to 92¢ a bushel ($26/m³) in 1816, equal to $12.6 today. Those areas suffering local crop failures had to deal with the lack of roads in the early 19th century, preventing any easy importation of bulky food stuffs.Also:
In China, the cold weather killed trees, rice crops, and even water buffalo, especially in northern China. Floods destroyed many remaining crops. Mount Tambora’s eruption disrupted China’s monsoon season, resulting in overwhelming floods in the Yangtze Valley in 1816. In India the delayed summer monsoon caused late torrential rains that aggravated the spread of cholera from a region near the River Ganges in Bengal to as far as Moscow.(For further information, see these articles at Science Daily, Wired, the Astronomical Society of the Pacific, and the Weather Doctor). LDS readers may find this interesting:
In New York City, the temperature dropped to −26 °F (−32 °C) during the ensuing bitter winter of 1817. This resulted in a freezing of New York's Upper Bay deep enough for horse-drawn sleighs to be driven across Buttermilk Channel from Brooklyn to Governors Island.
The effects were widespread and lasted beyond the winter. In eastern Switzerland, the summers of 1816 and 1817 were so cool that an ice dam formed below a tongue of the Giétro Glacier high in the Val de Bagnes. In spite of the efforts of the engineer Ignaz Venetz to drain the growing lake, the ice dam collapsed catastrophically in June 1818.
The crop failures of the “Year without a Summer” may have helped shape the settling of the "American Heartland", as many thousands of people (particularly farm families who were wiped out by the event) left New England for what is now western and central New York and the Upper Midwest (then the Northwest Territory) in search of a more hospitable climate, richer soil, and better growing conditions.(Underline added).
According to historian L.D. Stillwell, Vermont alone experienced a drop of 10,000 to 15,000 people, erasing seven previous years of population growth. Among those who left Vermont were the family of Joseph Smith, who moved from Sharon, Vermont, to Palmyra, New York. This move precipitated a series of events which culminated in the publication of the Book of Mormon and the founding of the Church of Jesus Christ of Latter-day Saints.
Although there is probably no connection, it is interesting that the New Madrid earthquakes began in late 1811 and went through early 1812--the time the major volcanic eruptions began.
The Astronomical Society of the Pacific makes a further interesting note:
A third factor also could have played a role. During both the Dalton and the Maunder minima, the Sun shifted its place in the solar system — something it does every 178 to 180 years. During this cycle, the Sun moves its position around the solar system's center of mass. This particular trick of gravity is known as "inertial solar motion." Scientists have not yet confirmed whether or not inertial solar motion affects Earth's climate directly, but it remains a possibility.Solar inertial motion, and its possible relationship to climate, is discussed here. (See also here and here and here).
From an eschatology position, it is notable that unlike many other prophecies that describe societal trends (e.g., declining morality), Revelations largely describes "black swan" events--earthquakes and other natural disasters, and the rise of a super-dictator. Looking back at the history of Rome, Rome had major systemic economic and political problems, but was able to keep teetering along. It was the added impact of a series of "black swan" events--pandemics, cooling temperatures, and foreign invasion--that finally brought down the whole edifice. Similarly, the collapse of the Soviet Union was probably hastened by Chernobyl and a disastrous and costly war in Afghanistan.
The trend lines have been clear for a long time in the United States. The long-term debasement of our currency combined with unaffordable social programs and a massive growth of the bureaucracy has put us in a similar position to Rome in the Second Century. Like Rome, we could probably continue for an indefinite period of time like this until a black swan event shakes things up--first crippling the government and then, finally, bringing it down.
Update (Nov. 7, 2014): There is a documentary about the Tambura explosion and its impact on North America and Europe available on Hulu. The documentary is part of a series of Pure History Specials, and entitled "The Year Without A Summer."