A seismometer is a scientific instrument designed and invented to record and measure which type of natural activity?

Introduction / Context:
Earthquakes are natural events in which energy stored in the Earth crust is suddenly released, generating seismic waves that travel through the ground. To study these events and to monitor seismic activity, scientists use sensitive instruments called seismometers. This question asks what type of natural activity such an instrument is designed to record and measure.

Given Data / Assumptions:

• The device mentioned is a seismometer.
• The question focuses on the kind of natural activity it records.
• The options include earthquakes, weather related phenomena and other geophysical processes.
• We assume familiarity with basic earth science terminology.

Concept / Approach:
The word seismo comes from a Greek term meaning shock or earthquake. A seismometer detects ground motions caused by seismic waves. It produces a seismogram, a trace that shows how the ground moved over time at a particular location. While other instruments record weather or magnetic field changes, the seismometer is specifically associated with earthquakes and related seismic events.

Step-by-Step Solution:
Step 1: Break the word seismometer into seismo plus meter, where seismo refers to shaking or earthquake. Step 2: Recall that earthquakes generate seismic waves, which are recorded by instruments in observatories. Step 3: Understand that these recordings help determine the time, location and magnitude of an earthquake. Step 4: Therefore, the seismometer records earthquake shocks and seismic waves, making option B correct.

Verification / Alternative check:
Geography and earth science textbooks always mention seismometers and seismographs when introducing earthquakes. Diagrams usually show a mass suspended in a frame that remains relatively still while the ground moves, producing a trace on paper or a digital record. No other natural phenomenon listed in the options uses this specific type of instrument for routine measurement, which confirms that earthquakes and seismic waves are the correct match.

Why Other Options Are Wrong:

• Changes in magnetic fields: Measured using magnetometers, not seismometers.
• Atmospheric pressure changes: Recorded with barometers or barographs.
• Ocean tides: Monitored using tide gauges and satellite altimetry, not seismometers.
• Wind speed in storms: Measured with anemometers, not earthquake recording instruments.

Common Pitfalls:
Some learners confuse seismometer with a general measuring instrument for any kind of natural vibration, including wind or waves in the ocean. Others may mix it up with meteorological instruments if they do not focus on the root word. To avoid these errors, always remember that seismology is the study of earthquakes, so a seismometer is firmly linked with seismic events and ground shaking.

Final Answer:
A seismometer is used to record and measure earthquake shocks and seismic waves.