With yet another quake off the coast of Australia, South Africans all over the world may be wondering whether they are safe or whether or not they need to be on the lookout for warnings of seismic activity.

In this issue of Travel Tuesday we’ll take a look at danger zones across the world.

Plate tectonics – the science behind quakes

Plate tectonics is the theory that the Earth’s outer shell is divided into several plates that glide over the mantle. The plates are hard and rigid shells compared the Earth’s mantle and the strong outer layer is called the lithosphere.

The theory of plate tectonics supposes that there is a large-scale motion of Earth’s lithosphere. The theory is based on the concept of continental drift and was developed during the 20^th century.

Why do plate tectonics cause earthquakes?

Plate movement, quite obviously, involves the movement of tectonic plates under earth’s surface. Although the Earth appears to be one solid spherical object, it is more like a bunch of puzzle pieces which are constantly moving around.  The mantle which is below the earth’s crust is not entirely solid and is instead a viscous fluid, causing the pieces on top of it to move around. Since these pieces don’t move congruously these ‘pieces’ slip past each other or crash into each other.

When this occurs, there is a sudden release of energy causing seismic waves which make the ground shake. These movements can also cause magma from Earth’s upper mantle to erupt or flow to the surface as is the case in volcanoes or it could cause massive waves called tsunamis.

Which areas of earth are most affected?

In general the areas along earth’s fault lines are most affected by earthquakes and volcanoes.

Fault lines

Image: courtesy of Creation and Science

Active volcanoes

Image: courtesy of The Volcano

Some of the biggest earthquakes recorded across the world (5+ on the Richter Scale) in the last week include:

• 20 July: 6,0 – 77 km from Tanna, Vanuatu
• 21 July: 5,4 – 278 km from Nuku’alofa, Tonga
• 23 July: 5,7 – 328 km from Yuzhno-Sakhalinsk, Russia
• 23 July: 4,3 – 4 km from Kealakekua, USA
• 23 July: 5,4 – 349 km from Bengkulu, Indonesia
• 23 Jul: 5,4 – 460 km from Acapulco, Mexico
• 23 July: 5,7 – 205 km from Savai’i, Samoa
• 25 July: 5,9 – 1904 km from Adelaide, Australia
• 25 July: 6,1 – 30 km from Chanaral, Chile
• 25 July: 6,4 – 127 km from Papua New Guinea

Of course, earthquakes and tremors occur every day, and in general they don’t affect human populations that much.  The problem comes in where dense populations are grouped closely along fault lines or in areas which may be affected by secondary disasters like tsunamis, volcanic eruptions landslides or fires.

Some of the greatest natural disasters in history linked to earthquakes include:

• 1556 Shaanxi earthquake – death toll of 830 000
• 1976 Tangshan earthquake – death toll of 450 000
• 2004 Indian Ocean earthquake and tsunami – death toll of 280 000
• 1920 Haiyuan earthquake – death toll of 273 400
• 526 Antioch earthquake – death toll of 250 000+
• 2010 Haiti earthquake – death toll of 100 000 – 316 000 (contested figures)

Cities which are most likely to be hit by an earthquake include:

• Tokyo, Japan
• Jakarta, Indonesia
• Manila, Philippines
• Los Angeles, USA
• San Francisco, USA
• Osaka, Japan
• Islamabad, Pakistan
• Mexico City, Mexico
• Tarapaca, Chile
• Izmir, Turkey
• Delhi, India
• Istanbul, Turkey
• Tehran, Iran
• Antofagasta, Chile
• Coquimbo, Chile
• Manus, Papua New Guinea
• Salta, Argentina
• Manabi, Ecuador
• Atacama, Chile

(sources: World Atlas,  Listaka and Earthquake Track)

What to do if you are travelling to high-risk earthquake zones?

Although many areas which are frequently affected by earthquakes (those along the ring of fire) have warning systems and disaster management in place for these eventualities, it’s good to be prepared.

Firstly, check for seismic activity in the area you will be visiting. You could check the latest news or visit Earthquake Track for more in depth earthquake maps.

Here’s our earthquake checklist for those travelling to high risk areas:

• If there has already been an earthquake, pack some portable chargers and Wi-Fi cards and be prepared for some delays as transportation may be a problem.
• Keep emergency numbers and contact information on your person so you and others will know who to contact in case of emergency.
• If an earthquake occurs while you are in the city/area – if you are indoors, take cover under heavy furniture like tables and steer clear of furniture which could topple, shatter or catch fire, if you are outdoors, try to steer clear of buildings, utility wires and roads.
• If you’ll be in the area for a while, stock up on some non-perishable food supplies, fresh water, and flash lights with spare batteries.
• You can purify water by adding 1 – 10 drops of bleach to it and letting it stand for at least 30 minutes before drinking. 1 Drop per litre if the bleach contains 7 – 10% of chlorine, 2 drops per litre if the bleach contains 4 – 6% chlorine, 10 drops per litre if the bleach contains 1% chlorine.
• Have a first aid kit available on your person, in your car or in your home.
• Remember special needs items like medication, glasses, contact lens solution, infant formula and diapers as well as sanitation supplies.
• Pre-determine a gathering point with your family or fellow travellers so you know where to reach each other in case of an emergency.
• Turn off any gas supplies and electrical supplies.
• If you are near the coast, try to move inland as soon as the ground has stopped shaking.
• Put on shoes before you venture outside or seek help as you may have to walk across debris.
• Find out in advance where emergency services are located so you can easily make your way there or contact them in case of emergency.

We wish all our readers safe travels and hope you will not be affected by any natural disasters.