As Hong Kong experienced a magnitude 4.1 earthquake yesterday (14th March 2022) morning at around 2:28 am, it shook Hong Kong people from their sleep and also from the myth that major natural hazards do not threaten Hong Kong. Concerns arise surrounding the earthquake and whether Hong Kong is prepared for the worst-case scenario.
The epicenter was located approximately 92 kilometers east-northeast of Hong Kong, near the coast of Southeastern China (22.51 N, 115.04 E). The Hong Kong Observatory has recorded over 10000+ reports on the felt earthquake.
As Hong Kong is located within the Eurasian Plate far away from the Circum-Pacific Seismic Belt that often affects the United States, Japan, Taiwan, Philippines, and more, the Observatory states that a local major quake is unlikely.
Even though we are far from the seismic zone, The Observatory has recorded 85 felt earthquakes (earthquakes larger than about magnitude 3.0) since 1979. Locally felt earth tremors happen more often than we thought, with an average of two felt earthquakes every year.
According to a recent study conducted by the Geotechnical Engineering Office, the return period for an Intensity V tremor and an Intensity VII tremor would be 30 – 40 years and 500 – 600 years, respectively.
Regarding the absence of the alert on yesterday’s earthquake, the Observatory states that they usually will issue quick earthquake reports via social websites and RSS to the public, and SMS and emails to media and news outlets when there is an Intensity V or above earthquake.
The Observatory also reassures the public that they collect timely seismic waveform data, earthquake and tsunami information from global and local seismograph networks to compute the origin time, epicenter, and magnitude.
Some may express concerns over whether buildings in Hong Kong are safe from earthquakes, especially when we are known for our extremely high residential density with high-rise buildings. Even though local construction is not seismic-resistant, most of it is built with a relatively high load-resisting capacity to withstand strong winds, and therefore, also meets the international standard on earthquake-resistant buildings, according to a consultation paper published by the Buildings Department.
Even though it is unlikely for Hong Kong to experience a major tremor, what should we do when we really encounter one? Follows the Drop, Cover, Hold principle:
- Stay calm.
- Drop down onto your hands and knees before the tremor intensifies.
- Cover your head and neck (and your entire body if possible) once you are sheltered.
- Hold on to your shelter until the shaking stops.
- Do not try to move around when the shaking is still happening.
To find your shelters nearby:
- If you are indoors, stay indoors, take cover under a sturdy piece of furniture, such as tables or desks, and stay away from windows, hanging objects, and glass.
- If you are unable to move from a bed or chair, protect yourself by covering yourself up with blankets and pillows.
- If there is no shelter nearby, get near the interior wall or low-lying furniture without loose objects on it. Try to grab something to cover up yourself from falling objects or shattered glass.
- If you are in a wheelchair or are unable to drop to the ground, remain seated and cover up your head and neck. Try to stay away from outer walls, windows, hanging objects and lock your wheelchair when sheltered.
- If you are near the shore, and the shaking has lasted for more than 20 seconds, immediately move to higher ground as the earthquake might have generated a tsunami.
- If you are in a moving vehicle, stay in the vehicle and stop driving until the shaking stops.
- If you are outside, move away from buildings, steep slopes, utility wires, trees, and try to move to open space.
Earthquake safety rules: