Lessons from an earthquake

19 Jan 2011

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balochistan earthquake
An earthquake survivor collects his belongings from his collapsed house near Ziarat October 31, 2008. - Photo by Reuters (File Photo)

While nature is a good teacher, natural disasters are tough teachers and taskmasters. Natural disasters can cause great harm to some and be fatal for others, however, they also result in many getting trained in the acts of rescue, evacuation and help.

Unfortunately, it is seen that few people learn or try to learn from nature and fewer still from natural disasters. And the lessons learnt are remembered for a short while only. This is particularly true in case of earthquakes. When a seismic contingency occurs, there is lot of passion in all sections of society and everybody tries to help the affected persons. Unfortunately, it has been seen that the print and electronic media try to project the destructive and disastrous part of the earthquake in a disproportionate way. Aspects such as scientific, seismological, geological, geophysical, management of disaster, etc., are either not reported or the coverage is minimal.

Quetta experienced a destructive earthquake on May 31, 1935. Its magnitude was around 7.5 on the Richter scale and the death toll was about 50,000. The then British Army was especially requested to study the engineering aspect of the seismic vibrations and asked to develop suitable measures so that structures could be made strong enough to sustain future seismic vibrations. The Army Corps of Engineers introduced a small but very effective measure to protect the houses from seismic forces. In a brick or stone masonry wall, horizontal holes of about 10mm diameter and the length equal to the wall’s thickness, were provided at vertical distances of 30 to 40cms. Reinforcement was inserted in these holes and fixed with mortar. Suchmeasures strengthened the walls and prevented their collapse. These are known as “Quetta bonds”.

Today, the Quetta bonds are totally forgotten in both Pakistan and India. However, the British Code for reinforced concrete masonry does mention the bond. Not only is the practice in vogue, but it is also known as inserting “headers”.

On October 8, 2005, an earthquake of the magnitude of 8.0 shook Muzaffarabad and its surrounding areas, and the death toll was about 100,000. On October 29, 2008, an earthquake of magnitude 6.5 hit Ziarat, with the epicentre at a distance of about 55 km from Quetta. This was followed by a number of aftershocks. The death toll was more than two hundred. As per reports, a number of reliable seismic precursors were observed.

It has been observed that a potential epicenter of the region experiences a thermal high few weeks before the occurrence of an earthquake. This is seen in the form of rise in minimum and maximum atmospheric temperatures. In the satellite pictures, which are available daily on the internet, a thermal high in maximum and minimum temperatures of about four to seven degrees above average was seen for about two weeks preceding the earthquake of October 29. Others must have seen this too.

For managing any natural disaster it is important to understand the three aspects related to disasters. These are the academic, physical and administrative aspects and there should be close cooperation and coordination between these three groups for the proper management of a disaster. A number of researchers are conducting research in seismology, geology, geophysics and allied subjects, and at present the mechanism of earthquake occurrence has been sufficiently understood. Most of these researchers try to confine their work to teaching or obtaining a degree. They should be made aware of the social responsibility of research as it can help in the seismic safety of several other sectors.

Furthermore, the use of modern equipment such as satellite photos and measurements of several geophysical, seismological and geological parameters are routinely being undertaken by a number of organisations. All these daily measurements need to be properly coordinated for seismic monitoring and observing any seismic precursory trend. This will help in a broad way to see whether the area is heading for any stress building activity and earthquake or not. If so, then some additional instruments can be deployed at the site for intensive monitoring. However, it is a fact that so far it has not been possible to predict the exact date, time, magnitude and location of an earthquake.

So far there has been only one successful case of earthquake prediction and that was in China. At present, most disaster management offices and administration are of the opinion that earthquakes cannot be predicted. They are both correct and wrong to some extent. A number of seismology researchers are claiming with a sufficient degree of confidence that earthquakes can be predicted. This difference of opinion between researchers and disaster managers has to change for an impression is inadvertently created that disaster management experts come into the picture only during post-seismic period to clear the debris and corpses.

The physical aspect of disasters is observed by the people as well as the administration of the place. Generally, the locals have some traditional knowledge and instincts that warn them about all natural happenings. But this traditional knowledge needs to be combined with scientific knowledge to make disaster management more effective. Thus, there is a need to create seismic awareness for this.

The administrative approach to disaster management has to be on scientific basis and need-based. Few administrators are trained in disaster management. Pakistan had suffered heavily in the Muzaffarabad earthquake and the administration had gained some experience in earthquake disaster management from that. This gain needs to be transformed, channelized and modulated in the form of systematic training to government officials and NGOs. Based on this experience, the administration may be geared up and trained to handle seismic disasters. Seismic training has to be imparted to all levels, including senior administrators such as the governor, chief minister, chief justice and speaker of legislative assemblies, and farmers, engineers, doctors, the common people, as well as in schools, colleges, universities, etc.

Farmers can give important seismic precursory information as a few weeks before a moderate to large earthquake, there is a sudden change in the water level of rivers, rivulets, etc. The water in wells suddenly rises. This was seen prior to the October 8 earthquake. Abnormal animal behaviour has been observed prior to an earthquake not only in Pakistan but also at the Bam and Gujarat earthquakes, in Iran and India respectively, and prior to all major earthquakes.

The damage to dwellings can be reduced if the construction is along seismic lines and old structures could be strengthened. To make a small beginning, it would be useful if masons were given suitable training. After Bhuj (Gujarat) earthquake of January 26, 2001, about 23,000 masons were trained in building seismic-resistant houses. Most self-made masons try to overlook or overdo the design or are not ready to accept seismic-resistant provisions. A suitably trained mason will built only a seismically-resistant house and such an activity would be highly effective. This type of work can be taken up immediately in Quetta and other seismically prone areas.

An example from China would help in understanding the point properly. On May 12, 2008, a magnitude 8.0 earthquake shook Sichuan (Wenchuan City) province of China and the death toll was around 70,000. Within two hours of the occurrence of the earthquake, a number of researchers from all over the world, including this scribe, had received e-mails from Chinese experts informing that some researchers informed the Chinese government about the likely occurrence of a destructive earthquake — the likely location, magnitude and date — some five to 15 days in advance.

This scribe was in China in October 2008 to attend the International Conference on Earthquake Engineering. This conference had devoted about five hours in the form of a special session to discuss the Sichuan earthquake.

The earthquake prediction claims could not be verified officially at this conference. But it was observed by the Chinese delegate that there was lack of co-ordination and cooperation between the academic fraternity and the concerned administration in handling the seismic scenario at Sichuan. This contains an important lesson for all future disaster management.

As per statistical calculations, the return periods of earthquakes of large magnitudes (of magnitudes greater than 7.0) in the Quetta region is of the order of about 75 to 80 years (+ or – 20). The last earthquake occurred in 1935. This means it is now a vulnerable time for Quetta and its surrounding areas. Leading seismo-statisticians should look into the probability of the occurrence of an earthquake of a large magnitude in this region.

Keeping this statistical observation in mind, the experience gained during the Muzaffarabad earthquake in 2005 and the small trial test earthquake of 6.5 magnitude, on October 29, the seismic situation at Quetta needs to be pondered over seriously and suitable plans to mitigate the disaster should be drafted and finalised at the earliest. Unfortunately, in most Asian countries, people expect the government to undertake all these activities. However, it would be better if other agencies such as colleges, universities and NGOs also extend a helping hand. Such efforts would need a smaller amount of money as compared to that required during the post-seismic period which includes compensation, rehabilitation, etc.

It is a bitter truth that no government official visits the common man during the pre-seismic period, but a number of officials will visit the earthquake-affected persons during the post-seismic period with food, tents, blanket, medicine, etc. if one is alive, and with large monitory compensation to the relatives, if one is dead. However, if a little effort is made to prepare for a disaster, it will go a long way in limiting the losses when it finally strikes.

Dr. Arun Bapat is a research seismologist from Pune, India.

*Published earlier in Dawn, December 2008