Jets were detected flying low over Beirut, the capital of Lebanon, causing a loud "sonic boom" to be heard over the city.
The loud explosion occurred on Thursday, September 19 during a statement by Hezbollah leader Hassan Nasrallah, warning that "the resistance in Lebanon will not stop" until the conflict in Gaza is resolved.
The attack, which sounded like jets breaking the sound barrier over the city, also happened during Sky’s John Sparks’s live report.
Israel's military said its jets struck hundreds of multiple rocket launcher barrels in southern Lebanon set to be fired immediately towards Israel.
The two countries have a decades-long history of conflict, including during recent months amid the Gaza War.
More than 600 people were injured and at least 25 were killed when Hezbollah's hand-held radios exploded late on Wednesday (September 18) afternoon, according to Lebanon’s health ministry.
The explosions happened throughout the southern part of the nation and Beirut's southern suburbs.
One blast took place near a funeral organised by Iran-backed Hezbollah held in honour of those killed the day before.
But what exactly is a sonic boom and is it harmful to humans?
Here’s what you need to know.
What is a sonic boom?
According to National Geographic, a sonic boom is the noise made when an airplane or another object travels faster than the speed of sound. This is typically around 343 metres per second (1,235 kilometres per hour or 767 miles per hour) at sea level.
When an object exceeds this speed, it compresses air in front of it, creating a shockwave that we hear as a loud boom. The noise is not just a single event; it's a continuous effect when the object moves at supersonic speeds, resulting in a "boom carpet" that can be heard for miles along the flight path.
Sonic booms are generally as loud as thunder or an explosion, with an average decibel level of 110.
Small things like whips and bullets can produce sonic booms, as can natural events like earthquakes, meteor showers, and volcanic eruptions. However, airplanes are most commonly linked to them.
The magnitude of a sonic boom is expressed in pounds per square foot of overpressure, and it rises in proportion to the size and velocity of the initiating item.
It’s not the first time sonic booms have been heard in Lebanon.
Analysts and locals informed Al Jazeera that Israel has been using low-altitude jet flights over Lebanon to produce them during the Gaza War, seemingly with the intention of frightening and intimidating the general population.
Lawrence Abu Hamdan, a sound expert and the founder of Earshot, a nonprofit that employs audio analysis to analyse state aggression and violations of human rights, claims that Israel exploits sonic booms as part of a larger trend of psychological warfare against the Lebanese people.
He said: “Since the truce of 2006, there have been more than 22,000 Israeli air violations of Lebanon. In 2020 alone, there were more than 2,000 [air violations] with no response from Hezbollah. They are an acoustic reminder that [Israel] can turn Lebanon into Gaza at any point.”
Sonic booms have been used before as a method of psychological warfare, not just in Lebanon but in other conflicts.
During the Vietnam War (1955-1975), the US used "Operation Bolo," where supersonic planes created sonic booms to intimidate North Vietnamese forces.
Nasa has been researching quieter supersonic flight technology, known as "low-boom" aircraft, to reduce sonic booms’s environmental and social impact.
Is a sonic boom dangerous to humans?
A sonic boom is generally not dangerous to humans, because the overpressure typically produced is too weak to cause harm.
However, stronger sonic booms can sometimes cause minor structural damage including broken windows.
While not physically harmful, the noise can be startling and cause psychological stress, especially in conflict zones where it's used for intimidation.
