Natural Hazards and Disasters

Hurricanes are the specific name for cyclonic storms that occur in the North Atlantic Ocean, particularly in the West Indies and Gulf of Mexico region. The same storm is called a typhoon in the western Pacific and simply a cyclone in the Indian Ocean.

Volcanic eruptions produce materials in all three states of matter: solid (pyroclastics like ash and rocks), liquid (lava/molten rock), and gas (water vapor, CO2, sulfur dioxide). This makes option C the correct answer.

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.

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.

Natural hazards are hazards which are caused because of natural phenomena (hazards with meteorological, geological or even biological origin). Examples of natural hazards are cyclones, tsunamis, earthquake and volcanic eruption which are exclusively of natural origin. Landslides, floods, drought, fires are socio-natural hazards since their causes are both natural and man made. For example flooding may be caused because of heavy rains, landslide or blocking of drains with human waste.

Willy-willy, most commonly known today as dust devils, is an upward spiralling, dust filled vortex of air that may vary in height from a few feet to over 1,000. They are usually several metres in diameter at the base, then narrowing for a short distance before expanding again. They mainly occur in desert and semi-arid areas, where the ground is dry and high surface temperatures produce strong updrafts.

Correct Answer: landslides

Caldera is the most explosive volcano.

Shield volcanoes are built almost exclusively of basalt, a type of volcanic rock that forms from low-viscosity lava flows. This lava can travel long distances before cooling, creating the broad, gently sloping shield shape. Other options are incorrect: salt is not volcanic, mercury and copper are individual metals not found in volcanoes, and gasoline is a refined petroleum product.

Severe Acute Respiratory Syndrome (SARS) is a viral respiratory disease of zoonotic origin caused by the SARS coronavirus.

Circum-Pacific belt is the most susceptible to earthquakes.

The Gulf of Mexico region is known for experiencing tornadoes, particularly during spring months when warm, moist air from the Gulf collides with cold continental air. Willy-willy is a term used in Australia for tropical cyclones, while cyclone is a general term and typhoon specifically refers to Northwest Pacific storms.

The condition of absence/deficit of rainfall from the normal is known as meteorological drought.

‘Seismograph’ measures the amount of energy released by an earthquake.