Dr. Muhammad Mahtab Hossain Mazed

Within a few days, Bangladesh was again shaken by an earthquake. The earthquake was felt across the country including the capital Dhaka at 7:05 a.m. on Tuesday (07 January). In addition to Bangladesh, Nepal, India, Bhutan and China's Tibet experienced a very strong earthquake, which was felt from many parts of the country, including Dhaka. The United States Geological Survey (USGS) says that the magnitude of the earthquake was 7.1 on the Richter scale at 7:05 a.m. Bangladesh time on Tuesday. .The epicenter of the earthquake was 93.9 km northeast of Labushe, Nepal, 163 km west-southwest of Rikaze, Tibet, 190.9 km northwest of Sikkim, India. The origin of the earthquake was 10.0 km below the surface.

The assistant meteorologist of Bangladesh Meteorological Department's Earthquake Monitoring and Research Center said that the earthquake occurred in China's Shizhang region (Tibet), 618 kilometers northwest of Dhaka. This earthquake was felt in different parts of the country including Dhaka. Many people were frightened by the tremors for several seconds in Dhaka. Although there is no information about the damage in this earthquake in Bangladesh, at least 36 people have lost their lives in the Chinese media. Earlier on January 3, an earthquake of magnitude 5 occurred in North East Myanmar, which was felt in different areas of BangladeshThe sudden and temporary shaking of the earth's surface is called an earthquake. "An earthquake is a shaking of the earth's crust of the earth." These vibrations, caused by the sudden release of stored energy in underground rocks, can range in magnitude from gentle vibrations to violent rotations. An earthquake is a type of wave motion energy, which originates in a limited area and spreads in all directions from the source of the event. Earthquakes usually last from a few seconds to a minute. Earthquake is not a new natural disaster in the history of the world. Earthquakes have been happening since time immemorial and will continue to happen in the future. People are completely helpless to these natural disasters. That's why today the thought of reducing earthquake damage as much as possible is going on all over the world. It is important to be aware of this. Adhering to proper building codes while constructing a building is important, especially knowing what to do to avoid earthquake damageEarthquake is the shaking of the ground. Earthquakes occur when one rock moves on top of another within the Earth. An earthquake is a sudden change in position or movement of a part of the earth's surface. If something in the house suddenly begins to sway—for example, a wall clock, hanging pictures, or any other furniture, including the bed—you should know that an earthquake is happening. In simple words, the shaking of the earth is an earthquake. And an earthquake is a natural disaster, which scientists have not yet figured out how to predict. In the main cities of our country, along with the increase in population, residential and non-residential buildings are increasing by leaps and bounds. But the quality of those structures, whether they will survive a major earthquake or not, is highly feared. Our big cities don't even have the open spaces needed as safe shelters in disasters like earthquakes. There are complaints that building codes are not followed in the construction of buildings in the country. As a result, even moderate earthquakes can cause severe disasters. And a large earthquake can cause a terrible human disaster. Therefore, in order to be protected from earthquake disasters, all types of structures should be built to cope with this disaster. There are an average of 6,000 earthquakes in the whole world every year. Most of them are subtle, which we don't notice. There are generally three types of earthquakes—major, moderate and mild. According to the depth of the source, earthquakes can be divided into three categories—shallow, intermediate and deep earthquakes. If the epicenter of the earthquake is within 70 km of the earth's surface, it is classified as shallow, between 70 and 300 km as intermediate and below 300 km as deep earthquake.

> Why do earthquakes happen?
When underground gas escapes through fissures or volcanic vents, the gas space is vacated and the pressure of the Earth's surface exerts pressure on the space to maintain equilibrium. It is then that strong tremors are felt on the earth's surface known as earthquakes. Earthquakes are generally caused by three main causes—sudden surface changes, volcanic eruptions, and landslides.

> Earthquake stability
Earthquakes usually last a few seconds. But this can cause massive destruction in a matter of seconds. Depending on the magnitude of the earthquake, there is massive loss of life and damage. The instrument used to measure the magnitude of an earthquake is called the Richter scale. Units on the Richter scale range from 1 to 10. A level higher than 5 on this scale means that there is a threat of severe disaster. A one degree increase in earthquake magnitude can increase from 10 to 32 times. Earthquake magnitude on the Richter scale—5 - 5.99 is moderate, 6 - 6.99 is severe, 7 - 7.99 is severe and 8 is extremely severe.

> How do earthquakes occur?

"Earth's crust is made up of separate bits, or plate tectonics, that float on top of the soft material below. There are seven major such plates and numerous smaller sub-plates all over the Earth. "

"When they move or move or push against each other, elastic energy is stored within the geology." When it exceeds the rock's carrying capacity, the energy is released through existing or new cracks. Then there is a vibration on the surface of the earth, that is an earthquake.

The places where one plate comes into contact with another plate or pushes or cracks are called fault lines.

And where the plate boundary is formed, we call it a fault line. Its surrounding countries are most prone to earthquakes.

The United Nations launched a program called the Global Seismic Hazard Assessment Program to identify earthquake-prone areas of the world. Its purpose was to create a map of the world's earthquake-prone regions to help prepare for damage.

Under that project, the world was divided into regions based on data and research on past earthquakes. Currently, the areas of the world that are of particular interest to scientists are:
> Earthquake risk and Bangladesh context

Among the natural disasters that occur, we have experience of floods, cyclones, floods, floods, etc., but we do not have the bitter knowledge of earthquakes. Incidentally, the United Nations says that Dhaka is one of the 20 most dangerous cities in the world Besides, Bangladesh is the worldDue to its location in an earthquake-prone region, earthquakes occur occasionally in this country since ancient times In addition, the Himalayan range is the most earthquake-prone region in Asia Although fortunately the people of Bangladesh did not have to accept the bitter taste of strong earthquakes, however, a review of the events of the last two centuries shows thatThere is a great fear of earthquakes in the north, north-east region, south-east region of Bangladesh For example, the deadly earthquake that occurred near Shillong in Meghalaya on June 12, 1897 caused many cities in Bangladesh, including Dhaka, Sylhet, and Mymensingh, to collapse and kill many people. Past 21stA major earthquake hit Chittagong and adjoining areas in November 1997, and in July-August 1999, Maheshkhali and surrounding areas were similarly hit by four earthquakes, resulting in several deaths and destruction of houses. In addition, according to records, 10 times in 1998There were 21 earthquakes in 1999 and 14 earthquakes till April 2000, which clearly indicates that earthquakes can strike Bangladesh at any moment. And only in the last year and a half, there have been 19 earthquakes in Bangladesh. Most of the magnitudes were between 4 and 5. According to USGS data, among the recent earthquakes that originated in Bangladesh, the highest magnitude was an earthquake that occurred on July 26, 2003. It is felt in Chittagong and Khagrachari. The magnitude was 5.6.
Bangladesh has experienced three earthquakes of more than magnitude 6 in the last one year. Two were 5.1 magnitudes on August 15, 2022. Most magnitudes were between 4 and 5. 10 were sourced from Chittagong and Cox's Bazar area.

From history it is known that due to earthquakes the course of rivers has changed or mountains and hills have been created Geologists and historians believe that the change in the course of the Brahmaputra river, the creation of Madhupur, is due to an earthquake. In addition, 19 million people live in an area of only 55 thousand square miles, unplanned urbanization andRisky unauthorized buildings will exacerbate potential earthquake damage In such a situation, it is absolutely necessary to gain proper knowledge about earthquakes and take necessary preparations and be aware
> What to do during an earthquake
* If you feel or hear about an earthquake, immediately take shelter in an empty and open place.
* If you are in a tall building and can't get out, stay under a strong beam or table instead of next to a window or wall.
* Deal with the situation patiently without panicking.
* In multi-storied buildings, many people should not stay together in the same place and take shelter separately.
* Keep fire services and useful mobile numbers in your mobile phone as early warning. You will be useful in times of danger.
* Do not jump off buildings to get down quickly.
* During an earthquake, if possible, hold a pillow or other solid object [cardboard, roll of soft cloth] firmly over the head.
* Keep away from gas and electrical connections.
* Do not use elevators to get down quickly from tall buildings.
* If you are in a car during an earthquake, stop the car in an open place and stay in the car.
* Once an earthquake is followed by another smaller earthquake which is called an 'aftershock'. Keep yourself free from danger. Therefore, to keep earthquake damage to a minimum level, public awareness should be developed. The government has to play the main responsibility in this regard, so that the potential damage is kept to a minimum level. From the beginning to the end of the construction of a building, the concerned person or organization must be strictly monitored to see if all the rules are followed or not.
Finally, the government should take proper steps to deal with the earthquake. In particular, provision of machinery to remove concrete piles after major earthquakes, identifying and demolishing or rectification of weak infrastructure in the city, proper adherence to building codes in construction of new buildings, strengthening of RAJUK, eradicating corruption from RAJUK, proper construction of buildings. Formulating and verifying the design, not building more than four-five floors in places, discouraging cluster housing, not constructing buildings by filling up water bodies, enforcing legal punishment for filling water bodies, restoring city canals, keeping rivers free from pollution and various public-private initiatives. About institutions and individualsFormation of earthquake cell etc.There is no substitute for public awareness to reduce earthquake damage.Earthquake awareness campaign in every ward of Bangladesh including Dhaka City Corporation, if earthquake awareness activities are taken occasionally in every office, it will greatly enliven the people of the city and people will be more aware of what to do during an earthquake.

Author, columnist and researcher Founder Chairman, Jatiya Rogi Kallyan Society Chamber, Alankar Shopping Complex Chittagong.