Indonesia
A massive supervolcano erupted at present-day Lake Toba around 70,000 BCE. It is believed to have caused a global volcanic winter and cooling of the climate, and subsequently led to a genetic bottleneck in human evolution, though this is still debated. The 1815 eruption of Mount Tambora and the 1883 eruption of Krakatoa were among the largest in recorded history. The former resulted in 92,000 deaths and created an umbrella of volcanic ash which spread and blanketed parts of the archipelago, and made much of Northern Hemisphere without summer in 1816. The latter produced the loudest sound in recorded history, and resulted in 36,000 deaths that are attributed to the eruption itself and the tsunamis it created. Significant additional effects were also felt around the world years after the eruption. Recent major disasters due to seismic activity include the 2004 Indian Ocean earthquake and the 2006 Yogyakarta earthquake.
Grotta Gigante horizontal pendulums
The movements of the pendulums has contributed to identify the free oscillations of the Earth, and to show that the secular term tilting of the cave is towards the northwest. The marine tides of the Adriatic have a loading effect in the cave, as have also the underground carstic floods of the river Timavo that disappears at the Skocjanske Cave in Slovenia. The Grotta Gigante tiltmeters are the only existing instruments to have recorded four out of five greatest earthquakes in the recent 50 years, which are the earthquakes of Chile 1960 (the greatest earthquake ever instrumentally recorded) and Chile 2010 (the fifth in the scale of recorded worldwide mega-events) the tsunami-generating event of the Sumatra-Andaman islands of 2004 (third greatest event) and the event of Japan 2011 (fourth greatest event), allowing an absolute-amplitude comparison between these events.