Mount Tambora 1815 eruption

Mount Tambora experienced several centuries of inactive dormancy before 1815, as the result of the gradual cooling of hydrous magma in a closed magma chamber. Inside the chamber at depths between 1.5–4.5 km (0.93–2.8 mi), the exsolution of a high-pressure fluid magma formed during cooling and crystallisation of the magma. Overpressure of the chamber of about 4,000–5,000 bar (58,000–73,000 psi) was generated, and the temperature ranged from 700–850 °C (1292–1562 °F). In 1812, the caldera began to rumble and generated a dark cloud.

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 6 April, 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 10 April on Sumatra island more than 2,600 km (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 cm (7.9 in) in diameter started to rain down at approximately 8 p.m., followed by ash at around 9–10 p.m. 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.

The explosion is estimated to have been VEI 7. It had roughly four times the energy of the 1883 Krakatoa eruption, meaning that it was equivalent to an 800 Mt (3.3×1012 MJ) explosion. An estimated 160 km3 (38 cu mi) of pyroclastic trachyandesite was ejected, weighing approximately 1.4e14 kg (3.1×1014 lb) (see above). This has left a caldera measuring 6–7 km (3.7–4.3 mi) across and 600–700 m (2,000–2,300 ft) deep. The density of fallen ash in Makassar was 636 kg/m² (130.3 lb/sq ft). Before the explosion, Mount Tambora was approximately 4,300 m (14,100 ft) high, one of the tallest peaks in the Indonesian archipelago. After the explosion, it now measures only 2,851 m (9,354 ft).

The 1815 Tambora eruption is the largest observed eruption in recorded history. The explosion was heard 2,600 km (1,600 mi) away, and ash fell at least 1,300 km (810 mi) away. Pitch darkness was observed as far away as 600 km (370 mi) from the mountain summit for up to two days. Pyroclastic flows spread at least 20 km (12 mi) from the summit. Due to the eruption, Indonesia's islands were struck by tsunami waves reaching a height of up to 4 m (13 ft).


Katyn massacre

The Katyn massacre, also known as the Katyn Forest massacre (Polish: zbrodnia katyńska, mord katyński, 'Katyń crime'; Russian: Катынский расстрел Katynskij ra'sstrel 'Katyn shooting'), was a mass execution of Polish nationals carried out by the People's Commissariat for Internal Affairs (NKVD), the Soviet secret police, in April and May 1940. The massacre was prompted by Lavrentiy Beria's proposal to execute all members of the Polish Officer Corps, dated 5 March 1940. This official document was approved and signed by the Soviet Politburo, including its leader, Joseph Stalin. The number of victims is estimated at about 22,000, with 21,768 being a lower bound. The victims were murdered in the Katyn Forest in Russia, the Kalinin and Kharkiv prisons and elsewhere. Of the total killed, about 8,000 were officers taken prisoner during the 1939 Soviet invasion of Poland, another 6,000 were police officers, with the rest being Polish intelligentsia arrested for allegedly being "intelligence agents, gendarmes, landowners, saboteurs, factory owners, lawyers, officials and priests."

The term "Katyn massacre" originally referred specifically to the massacre at Katyn Forest, near the villages of Katyn and Gnezdovo (approximately 19 kilometers/12 miles west of Smolensk, Russia), of Polish military officers in the Kozelsk prisoner-of-war camp. This was the largest of several simultaneous executions of prisoners of war. Other executions occurred at the geographically distant Starobelsk and Ostashkov camps, at the NKVD headquarters in Smolensk, and at prisons in Kalinin (Tver), Kharkiv, Moscow, and other Soviet cities. Still more executions took place at various locations in Belarus and Western Ukraine, based on special lists of Polish prisoners, prepared by the NKVD specifically for those regions. The modern Polish investigation of the killings covered not only the massacre at Katyn forest, but also the other mass murders mentioned above. Polish organisations, such as the Katyn Committee and the Federation of Katyn Families, consider the victims murdered at the locations other than Katyn as part of the overall massacre.

The government of Nazi Germany announced the discovery of mass graves in the Katyn Forest in 1943. When the London-based Polish government-in-exile asked for an investigation by the International Red Cross, Stalin immediately severed diplomatic relations with it. The Soviet Union claimed the victims had been murdered by the Nazis, and continued to deny responsibility for the massacres until 1990, when it officially acknowledged and condemned the perpetration of the killings by the NKVD, as well as the subsequent cover-up.

An investigation conducted by the Prosecutor General's Office of the Soviet Union (1990–1991) and the Russian Federation (1991–2004), has confirmed Soviet responsibility for the massacres. It was able to confirm the deaths of 1,803 Polish citizens but refused to classify this action as a war crime or an act of genocide. The investigation was closed on grounds that the perpetrators of the massacre were already dead, and since the Russian government would not classify the dead as victims of Stalinist repression, formal posthumous rehabilitation was ruled out. The human rights society Memorial issued a statement which declared "this termination of investigation is inadmissible" and that their confirmation of only 1,803 people killed "requires explanation because it is common knowledge that more than 14,500 prisoners were killed." In November 2010, the Russian State Duma approved a declaration blaming Stalin and other Soviet officials for having personally ordered the massacre.