Volcanoes and Earthquakes

Seismology

Step 1: Each natural science has its own branch of study. Step 2: Geology is the study of the earth's structure and rocks. Step 3: Meteorology is the study of weather and atmosphere. Step 4: Vulcanology (or volcanology) is specifically the study of volcanoes. Step 5: SEISMOLOGY comes from the Greek word 'seismos' meaning earthquake — it is the science dedicated to the study of earthquakes. The instrument used to record earthquake waves is called a Seismograph. So the correct answer is Seismology.

Epicentre

Step 1: An earthquake originates at a point inside the earth. Step 2: The point of origin INSIDE the earth is called the FOCUS or HYPOCENTRE. Step 3: The point on the earth's SURFACE that is directly above the focus is called the EPICENTRE. Step 4: The shaking is strongest at the epicentre because it is closest to the source of the earthquake. Step 5: As we move away from the epicentre, the intensity of shaking decreases. So hypocentre = underground origin, epicentre = point on surface above it.

1935

Step 1: Earthquakes are measured using two main scales — the Mercalli Scale (intensity) and the Richter Scale (magnitude). Step 2: The Richter Scale measures the magnitude of an earthquake based on the energy released at the earthquake centre. Step 3: It was devised by the eminent seismologist Charles F. Richter in the year 1935. Step 4: It was later modified in 1965 by Richter and his colleague Beno Gutenberg. Step 5: Note: 1965 refers to when it was modified, not when it was originally created — 1935 is the correct year of origin.

The volcanic belt along the borders of the Pacific Ocean

Step 1: Volcanoes are not randomly distributed on the earth — they follow specific belts. Step 2: The most important volcanic belt in the world is found along the borders (coasts) of the Pacific Ocean. Step 3: This belt contains about 403 active volcanoes out of the world's total — that is about 83% of all active volcanoes. Step 4: Because of the intense volcanic and earthquake activity along the Pacific coasts, this belt is dramatically called the 'Ring of Fire'. Step 5: The Alpine-Himalayan belt (option C) is called the Mid-World Belt, not the Ring of Fire.