VIDEO: Elephants form 'alert circle' to protect their young when earthquake hits southern California

US Geological Survey said that a 5.2-magnitude earthquake shook Southern California on Monday morning, with the tremor centred 2.5 miles (four kilometres) south of Julian, which is around 20 miles from the US border with Mexico. It was eight miles deep and was followed by several aftershocks. There were no immediate reports of death or serious damage, and scientists said structural problems were unlikely.

USGS said that the quake struck at 10:08 am (local time). It was felt as far north as Los Angeles County, about 120 miles (193 kilometres) away. The quake caused panic among people in Julian, which is a mountain town of about 1,500 people that is known for its apple pie shops.

Add WION as a Preferred Source

But amid chaos, a surreal moment was captured at the San Diego Zoo Safari Park where elephants instinctively circled their young, as soon as they felt the earthquake.

The zoo authority said that this behaviour is known as an "alert circle" and is intended to protect the young — and the entire herd — from threats.

The "alert circle" or "flight distance" basically refers to the area around an animal within which it becomes alert or vigilant when a potential threat, such as a predator or human, enters.

The zoo said the herd went back to normal after about 4 minutes, though they did stay close to one another.

When an intruder breaches this invisible boundary, the animal may exhibit behaviours like increased vigilance, freezing, fleeing and defensive posturing.

The size of the alert circle varies depending on the species, individual animal and environment. It is essential for wildlife observation, conservation and animal handling to understanding this concept.

Watch the video here:

More about earthqaukes in the region

Several fault lines cause frequent tremors along the US West Coast, which is the meeting point of tectonic plates. Several major earthquakes have occurred in Southern California, including one that struck Northridge in the Los Angeles region in 1994, leaving thousands injured and dozens dead.

In addition, it damaged homes and infrastructure to the tune of billions of dollars. Up to 3,000 people are believed to have been killed in the 1906 San Francisco earthquake and tsunami, some of whom died in fires that broke out following the strong jolt.