A shallow magnitude 4.2 earthquake struck Bangladesh early on Friday, May 5, 2023, 20 kilometers (12 miles) southwest of Dhaka. This earthquake’s origin had a very shallow depth of 10 kilometers. Generally, shallow earthquakes have a greater impact than deep earthquakes. The most recent tremor of magnitude 4 has renewed concerns regarding Bangladesh’s earthquake preparedness.
The earthquake is the only natural disaster that cannot be predicted by science and technology. Even the most advanced human-made technology won’t warn us minutes before a tremor, no matter how mild or severe it is, causes chaos in a specific region of the planet Erath. Due to this element of unpredictability, earthquakes are the most resented and can often prove to be deadly.
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It is estimated that an earthquake occurs somewhere on Earth every 30 seconds. However, the majority of them are too tiny to be identified. A magnitude 4.0 earthquake is only equivalent to about six tons of TNT explosives, but since the Richter scale is a base-10 logarithmic scale, the energy released increases exponentially. Increasing the impact, a magnitude 9.0 earthquake can be equal to 99,000,000 tons of TNT. According to the USGS, approximately 99 million tons of TNT is sufficient to destroy anything and is equivalent to approximately 25,000 nuclear weapons.
Frequency of earthquake in Bangladesh
In the past 10 years, 545 earthquakes of magnitude 4 or greater have occurred within 300 kilometers (186 miles) of Bangladesh. This equates to an annual average of 54 earthquakes, or four per month. On average, a tremor takes place near Bangladesh every six days.
In 2020, a significant number of earthquakes occurred near Bangladesh. That year, 86 earthquakes with magnitude 4+ were detected within 300 kilometers of Bangladesh. The greatest magnitude was 5.9 magnitude. Just few days ago, A shallow magnitude 4.2 earthquake struck Bangladesh on early morning.
Why Bangladesh is at high risk of earthquake?
Bangladesh is situated at the juncture of the Indian, Eurasia, and Burmese tectonic regions. The Indian plate is currently migrating approximately 6cm per year to the north-east, while the Eurasian plate is moving approximately 2cm per year above the Indian plate. There are five main fault zones in Bangladesh and surrounding regions, namely the Bogura fault zone, the Tripura fault zone, the Shilong Plateau, the Dauki fault zone, and the Assam fault zone. Thus, Bangladesh is home to thirteen earthquake-prone regions, including Chattogram, Chattogram Hill Tracts, and Jaintapur of Sylhet.
Dhaka, the capital of Bangladesh, had a population density of 30,093 people per square kilometer in 2022, placing it among the world’s most populous cities and has been identified as one of the twenty cities in the globe most prone to earthquakes.
Bangladesh to face fatal consequences with high magnitude earthquakes
When a 7.8 magnitude earthquake struck Turkey and Syria, killing approximately 59,000 people, the entire globe suddenly felt helpless. Countless others were injured, and roughly 0.87 million individuals were displaced. Likewise, the infrastructure was severely damaged, as 6,589 buildings collapsed. The estimated amount of material damage is approximately $ 89.2 billion. The effects of this single earthquake on the two countries are extensive and long-lasting. If an earthquake with that magnitude ever hits Bangladesh, what could happen?
In Dhaka city, where breach of building codes is prevalent and many tall buildings were built before the responsibility of the authorities emerged to make some attempts at enforcing the building codes, the effects of a powerful earthquake will be no less than an unprecedented calamity. Old Dhaka will likely be the epicenter of the worst catastrophe. In recent years, there has been an increase in the number of minor and moderate earthquakes within the country and on its borders. In contrast, the preparation to combat the threat appears inadequate.
According to the latest research, the capital city of Dhaka would also be severely damaged by an earthquake on the Dawki faultline in Sylhet, the second of two faultlines on which Bangladesh is situated. In this scenario, at least 40,935 structures and 16,000 individuals will be destroyed.
Unplanned and unsafe urbanization
There are two phases to managing seismic disasters. The first is pre-earthquake precautions, and the second is adopted by all after the disaster. One Taka spent on prevention saves ten Taka when a disaster occurs. It includes regulations, rigorous monitoring, and an early warning system.
As the most populous city in the world, Dhaka is inherently a high-risk zone for natural and man-made disasters. Furthermore, there is the issue of hazardous buildings, which are built frequently without following construction rules or by filling in wetlands. The majority of them are not resistant to earthquakes and continue to be inadequately maintained, resulting in several fires and explosions in recent weeks. In addition to the absence of concern and greed on the part of building owners, RAJUK is primarily responsible for the unplanned urbanisation of the region and the deplorable condition of many residential and commercial buildings.
Lack of adequate preparation in response to disaster
Clearly, the authorities lack the concepts and initiatives necessary to meet the challenges. A series of building disasters has exposed the deficiency and inadequacy of preparation. Even measures to prevent a recurrence of fire incidents in market buildings susceptible to fire catastrophes could not be taken, let alone for buildings at high risk for earthquakes.
Can we ever prepare for earthquakes?
If the minor tremors are an indication of a much greater threat, preparations should be made immediately. First, the most earthquake-vulnerable structures must be demolished without delay, followed by various other measures such as retrofitting, if feasible, to make buildings marginally safer. Regarding new construction, earthquake-resistant plans and designs must be adhered to.
If experts are to be believed, compliance with building codes may not be enough to prevent disasters if a powerful earthquake of magnitude 7.0 to 8.0 strikes in areas where the soil is soft and brittle. This demonstrates that the expansion of Dhaka on its periphery with housing complexes, particularly in areas of water retention or flood plain, was not prudent. There is a need to prevent similar developments in the future. This brings the issue of halting rural migration to Dhaka back to the forefront.
Now comes the issue of immediate earthquake rescue operations. Several decades ago, the Bangladesh Fire Service and Civil Defence trained volunteers. Block-by-block earthquake exercises are required in residential areas to educate residents on what to do and what not to do in the event of an earthquake. Some government institutions conduct drills from time to time. However, the common populace has the greatest need for such exercises. A major tragedy, like the one we saw during the rescue operation following the Rana Plaza collapse, is waiting for us if we don’t begin doing area-wide drills for them.