Residents in several parts of Kenya's capital, Nairobi, reported seismic movements on Tuesday at 8:31 p.m., raising concerns about potential structural damage and safety risks. Aftershocks were reported in several areas, including Ruaka, Lower Kabete, and Kangemi.

According to Volcano Discovery, a website that provides information on geological activities, there are no details on the magnitude or depth of the possible quake, which was first reported at 8:31 p.m.

But what is an earthquake, and how does it differ from an earth tremor?

Earthquakes and tremors are natural geological phenomena that cause the Earth's surface to shake or move. However, the two differ in terms of intensity, magnitude, and potential damage.

Earthquake:

• A violent shaking of the ground that usually causes widespread devastation as a result of movements in the Earth's crust or volcanic activity.
• Earthquakes have a higher magnitude on the Richter or moment magnitude scale and can range from minor to catastrophic in intensity.
• They can cause significant damage to property and lives.

Earth Tremor:

• A small, brief movement of the Earth's surface caused by the same forces that cause earthquakes.
• Tremors are typically smaller and less intense, with a lower magnitude than earthquakes.
• They generally do not cause significant damage, though they may cause minor concerns such as windows rattling or objects swaying.

When a tremor exceeds five on the moment magnitude scale (a scale of 0 to 10), it is classified as an earthquake.

Causes:

• Earthquakes: Caused when rocks break under stress against an underground surface known as a fault plane.
• Tremors: Relatively mild and caused by similar geological forces, but they are less intense and shorter in duration, usually lasting about 10 seconds.

Frequency and Impact:

• Earthquakes occur less frequently, with varying time intervals between events, and have the potential to cause significant damage.
• Tremors occur more frequently, with multiple events potentially happening within a short period, but they are less intense and generally do not cause significant damage.

According to Volcano Discovery, since 2022, Kenya has experienced three earthquakes with magnitudes greater than 4 and up to 5.0.