Natural Hazards: Earthquakes and Volcanoes

Correct answer is (1). 

Correct Answer: there has been increased deforestation in the catchment areas

A caldera is a large volcanic crater formed by the collapse of a volcano into itself after a massive eruption empties the magma chamber. This creates a collapsed depression, making option C correct. They are not a type of lava, specific to North America, or simply a synonym for volcanoes.

A seismometer is the scientific instrument used to detect and record the intensity, direction, and duration of seismic waves from earthquakes or explosions. Barometers measure air pressure, hydrometers measure liquid density, and altimeters measure altitude.

The epicentre is the point on Earth's surface directly above the focus (hypocentre), which is the actual location inside Earth where the earthquake originates. The epicentre is therefore the first point on the surface to experience earthquake waves, not the focus/hypocentre which is underground.

All three options listed (Blizzard - severe snowstorm, Lahar - volcanic mudflow, Drought - prolonged water shortage) are natural hazards. Therefore, saying 'None of these' means none of them is NOT a natural hazard, which is correct.

Calderas represent the most explosive volcanic systems, formed by massive eruptions that empty magma chambers causing ground collapse. Shield volcanoes are least explosive (lava flows), composite volcanoes are moderately explosive, while caldera-forming eruptions are the most violent (e.g., Yellowstone, Krakatoa).

Cyclone occurs in the Bay of Bengal.

Water vapor (H2O) constitutes about 60-90% of all volcanic gas emissions by volume. While CO2 and SO2 are significant, water vapor is by far the most abundant. Helium is present only in trace amounts. This makes option A correct.

Frequent earthquakes along the Himalayas and its foothills are caused by the ongoing tectonic collision between the Indian Plate and the Eurasian Plate, which falls under the framework of plate tectonics.