Apr 102019
 

On this date in 1815 the eruption of Mount Tambora, one of the most powerful in recorded history, reached its peak. With a Volcanic Explosivity Index (VEI) of 7, it is the most recently known VEI-7 event and the only unambiguously confirmed VEI-7 eruption since the Lake Taupo eruption in about 180 CE. By comparison, the explosion of Krakatoa in 1883 (http://www.bookofdaystales.com/krakatoa/ ) which produced the loudest explosion ever recorded, was a mere VEI-6 event. Indonesia has its moments.

Mount Tambora experienced several centuries of dormancy before 1815, caused by the gradual cooling of hydrous magma in its closed magma chamber. Inside the chamber at depths between 1.5 and 4.5 kilometers (0.93 and 2.80 mi), the exsolution of a high-pressure fluid magma formed during cooling and crystallization of the magma. An over-pressurization of the chamber of about 4,000–5,000 bar (58,000–73,000 psi) was generated, with the temperature ranging from 700–850 °C (1,292–1,562 °F). In 1812, the volcano began to rumble and generated a dark cloud.

On 5th April 1815, a very large eruption occurred, followed by thunderous detonation sounds heard in Makassar on Sulawesi 380 kilometers (240 mi) away, Batavia (now Jakarta) on Java 1,260 kilometers (780 mi) away, and Ternate on the Molucca Islands 1,400 kilometers (870 mi) away. On the morning of 6th April, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10th April. What was first thought to be the sound of firing guns was heard on 10th April on Sumatra, more than 2,600 kilometers (1,600 mi) away.

At about 7 pm on 10th April, the eruptions intensified. Three columns of flame rose up and merged. The whole mountain was turned into a flowing mass of fire. Pumice stones of up to 20 centimeters (7.9 in) in diameter started to rain down around 8 pm, followed by ash at around 9–10 pm. 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. The ash veil spread as far as West Java and South Sulawesi. A nitrous odor was noticeable in Batavia, and heavy tephra-tinged rain fell, finally receding between 11th and 17th April.

An estimated 41 cubic kilometers (9.8 cu mi) of pyroclastic trachyandesite were ejected, weighing about 10 billion tonnes. This left a caldera measuring 6–7 kilometers (3.7–4.3 mi) across and 600–700 meters (2,000–2,300 ft) deep. The density of fallen ash in Makassar was 636 kg/m3 (1,072 lb/cu yd). Before the explosion, Mount Tambora’s peak elevation was about 4,300 meters (14,100 ft), making it one of the tallest peaks in the Indonesian archipelago. After the explosion, its peak elevation had dropped to only 2,851 meters (9,354 ft), about two-thirds of its previous height. The 1815 Tambora eruption is the largest observed eruption in recorded history. The explosion was heard 2,600 kilometers (1,600 mi) away, and ash fell at least 1,300 kilometers (810 mi) away.

All vegetation on the island was destroyed. Uprooted trees, mixed with pumice ash, washed into the sea and formed rafts up to 5 kilometers (3.1 mi) across. Between 1st and 3rd October the British ships Fairlie and James Sibbald encountered extensive pumice rafts about 3,600 kilometers (2,200 mi) west of Tambora. Clouds of thick ash still covered the summit on 23rd April. Explosions ceased on 15th  July, although smoke emissions were observed as late as 23rd August. Flames and rumbling aftershocks were reported in August 1819, four years after the event.

A moderate-sized tsunami struck the shores of various islands in the Indonesian archipelago on 10th April, with a height of up to 4 meters (13 ft) in Sanggar around 10 pm. A tsunami of 1–2 meters (3 ft 3 in–6 ft 7 in) in height was reported in Besuki, East Java, before midnight, and one of 2 meters (6 ft 7 in) in height in the Molucca Islands. The total death toll has been estimated to be around 4,600.

The eruption column reached the stratosphere at an altitude of more than 43 kilometers (141,000 ft). The coarser ash particles settled out one to two weeks after the eruptions, but the finer ash particles stayed in the atmosphere from a few months to a few years at altitudes of 10–30 kilometers (33,000–98,000 ft). Longitudinal winds spread these fine particles around the globe, creating optical phenomena. Prolonged and brilliantly colored sunsets and twilights were seen frequently in London between 28th June and 2nd July, and 3rd September and 7th October 1815. The glow of the twilight sky typically appeared orange or red near the horizon and purple or pink above.

During the northern hemisphere summer of 1816, global temperatures cooled by 0.53 °C (0.95 °F). This very significant cooling directly or indirectly caused 90,000 deaths. The eruption of Mount Tambora was the most significant cause of this climate anomaly. While there were other eruptions in 1815, Tambora eclipsed all others by at least one order of magnitude (VEI-7 is ten times stronger than VEI-6).

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 by about 0.4 to 0.7 °C (0.7 to 1.3 °F), enough to cause significant agricultural problems around the globe. On 4th June 1816, frosts were reported in the upper elevations of New Hampshire, Maine, Vermont, and northern New York. On 6th 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 6th to 10th June 1816.

Sumbawa’s cuisine contains numerous dishes that are common to Indonesia but with their own twist. Babingka cake can be found throughout the region, but Sumbawa’s is a little simpler than others. It is made with ketan flour, a flour made from glutinous rice.

Babingka

Ingredients

250 gm ketan flour
100 gm grated coconut
250 ml coconut milk
100 gm brown sugar
25 ml white sugar

Instructions

Preheat the oven to 170°C.

Line a greased 8” x 10” baking tin with baker’s parchment.

In a large bowl, mix all the ingredients together thoroughly. Pour into the baking tin, and bake until golden (about 40 minutes).

Cool in the tin a few minutes, then turn on to a wire rack and let cool completely. Cut into squares.