# Q2A · Illustrate and explain in detail with neat sketch 3 types of waves for earthquakes. A…

Subject: Disaster Management

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/dm/#tee/papers/paper-2026-05-15/q2a

Canonical: https://deep-learning-study-room.vercel.app/read/dm/tee/papers/paper-2026-05-15--q2a/

Actual TEE paper · 100 marks · 3 hours · Q1 + any four of Q2–Q7

### Q2A. Illustrate and explain in detail with neat sketch 3 types of waves for earthquakes. Also state the 2 types of earthquakes on earthquake on basis of plate boundaries [10 marks]

#### Answer

**Definition.** Seismic waves are disturbances carrying earthquake energy. Body waves travel through the Earth; surface waves propagate along its surface.

Swipe across the diagram to read its labels ↔

![Seismic waves: compare particle motion](https://deep-learning-study-room.vercel.app/dm/fig/waves.3b808bf75c.svg)

Diagram: Seismic waves: compare particle motion. Labels: Seismic waves: compare particle motion | Seismic waves: compare particle motion | P wave · body wave | Push and pull parallel to travel: alternating compression and expansion. | S wave · body wave | Shearing motion perpendicular to the direction of wave travel. | Love wave · surface wave | Horizontal side-to-side shear, shown here from above. | Rayleigh wave · surface wave | Approximately elliptical rolling motion, shown in a vertical side view. | particle | particle | particle | rolling | travel → | travel → | travel → | travel → | Particle paths illustrate local movement; the wave carries energy onward.

Compare the direction of energy travel with the local movement of ground particles.

| Wave | Particle movement | Travel / key point |
| --- | --- | --- |
| P: primary | Compression and expansion parallel to travel direction. | Fastest body wave; travels through solids and fluids. |
| S: secondary | Shearing perpendicular to travel direction. | Slower than P; cannot propagate through liquids as shear waves. |
| Love | Horizontal side-to-side surface motion. | Surface wave; produces strong lateral shaking. |
| Rayleigh | Rolling, approximately elliptical motion in a vertical plane. | Surface wave with vertical and horizontal ground movement. |

“Direction of travel” means where wave energy moves. “Particle movement” means how a small part of the ground moves locally. A particle need not travel all the way from the fault to your city. Do not list Love waves as body waves.

## How shaking is recorded

A **seismometer** senses ground movement. A **seismograph** is the sensing-and-recording system; a **seismogram** is its record. A classical instrument uses inertia: the supporting ground moves relative to a suspended mass. Modern electronic instruments record a time series. Sensor, recorder and timing reference are the three basic components.

## Why P–S arrival separation is useful

P waves arrive first because they travel faster. The P–S time gap generally increases with source distance. Records from several stations constrain earthquake location. One station alone does not uniquely locate an epicentre; real location calculations use travel-time models.

## Interplate and intraplate earthquakes

**Interplate** earthquakes occur at plate boundaries. **Intraplate** earthquakes occur within a plate, commonly on reactivated faults. Boundary setting is different from classification by depth or by tectonic/volcanic origin.

#### Illustrative application · A classroom earthquake illustration

A fault begins to rupture below ground at the focus. The surface point vertically above it is the epicentre. Waves spread outward and shake buildings; the damage also depends on local ground and construction. Use the labelled diagram in the earthquake chapter to connect these terms.