Days after the devastating earthquake in Nepal, The Economist has published an article on big earthquakes in the last 20 years and their geographical occurrence, triggering us to write on the issue with an African perspective. Why and where earthquakes happen is controlled by plate tectonics. Seismically most active areas are convergent margins, i.e. where continental and or oceanic plates collide with each other. This includes almost the entire eastern coast of the Americas, a trail from Japan to New Zealand via Indonesia and Fiji, and a belt from Turkey to China, including Himalayas where the recent Nepal earthquake occurred.
Interestingly, the Alps have been spared of massive earthquakes during the timeframe. Historically, a few earthquakes between 6-7 in magnitude occur in the Alps region each century (source), such earthquakes may still cause big damages and hundreds or even thousands of casualties. The map by The Economist shows two earthquakes in Africa. In 1995 There was an earthquake in Sinai, Egypt (magnitude 7.2) while in 2006 earth shook in Mozambique at the magnitude of 7.0. Both are part of the Great Rift Valley system. This rift system is a prime example of a continental divergent margin. While earthquakes there are not uncommon, they tend to be lower of magnitude than in convergent margins. Yet even smaller earthquakes can create substantial damage due to poor infrastructure where buildings collapse even on their own. Earthquakes occur also in the northeastern part of the the continent along the Atlas mountains, which are tectonically related to the convergent margin between African and Eurasian plates. The table below lists major earthquakes in Africa since 1950. The list contains earthquakes exceeding 6 in magnitude, or less if significant casualties. The list is based on available Wikipedia articles (linked), and may miss some notable earthquakes. The magnitudes are either in Richter or Moment Magnitude scale, which differ somewhat from each other. Table 1. List of major earthquakes in Africa since 1950.
|Earthquake (with Wikipedia link)||Location||Magnitude||Deaths|
|1954 Chlef earthquake||Chlef, Algeria||6.8||1250|
|1955 Alexandria earthquake||Alexandria, Egypt||6.3||18|
|1960 Agadir earthquake||Agadir, Morocco||5.7||12000|
|1966 Toro earthquake||DRC/Uganda, Ruwenzori area||6.8||157|
|1969 Sharm_el-Sheikh earthquake||Sharm el-Sheik, Egypt||6.6||2|
|1980 El_Asnam earthquake||Chlef, Algeria||7.3||3500|
|1989 Malawi earthquake||Central Malawi||6.6||9|
|1992 Cairo earthquake||Dashur/Cairo, Egypt||5.8||545|
|1995 Gulf of Aqaba earthquake||Sinai, Egypt||7.3||8|
|2002 Kalehe earthquake||Lake Kivu, DRC||6.2||2|
|2003 Boumerdes earthquake||Thenia, Algeria||6.2||2266|
|2004 Al Hoceima earthquake||Al Hoceima, Morocco||6.4||629|
|2005 Lake Tanganyika earthquake||DRC/Tanzania, Lake Tanganyika||6.8||2|
|2006 Mozambique earthquake||Machaze, Mozambique||7.0||4|
|2008 Lake Kivu earthquake||Lake Kivu, DRC/Rwanada||5.9||44|
|2009 Karonga earthquakes||Karonga, Malawi||6||4|
Other natural disasters are beyond the scope of this article, but many of them like volcanic eruptions, tsunamis, landslides, avalanches may be either triggered by earthquakes or at least be related to same tectonic processes, thus often occurring is same areas as earthquakes. Even if they occur time to time, earthquakes won’t be the foremost safety concern when travelling in Africa. Even in Chile, Japan, Nepal or Indonesia, where major earthquakes are more common, the risk of being caught by one is very slim. These are all great destinations and skipping them because of earthquakes is like not flying because of those few accidents that happen (and thus using less safe modes of transport…).