Earthquakes – timeline
A look at some of the historical aspects of earthquakes, find out how our understanding of what causes earthquakes has changed.
1705 – A discovery by Robert Hooke
Robert Hooke realised that earthquakes are connected to land movements.
1755 – Modern studies begin
A huge earthquake and tsunami in Portugal killed over 70,000 people. This marked the start of modern earthquake studies, as people began to collect data to help understand the events.
1840 – Electromagnetic seismograph invented
Luigi Palmieri invented the first accurate electromagnetic seismograph, which could detect earthquakes not felt by humans.
1850 – Seismic waves discovered
Robert Mallet realised that most earthquake damage is due to moving waves caused by a sudden land movement, named seismic waves.
Seismic waves
When an earthquake occurs shockwaves of energy, called seismic waves, are released from the earthquake focus. They shake the Earth and temporarily turn soft deposits, such as clay, into jelly (liquefaction).
1855 – Layer of rocks discovery
John Pratt and George Airy suggested that surface rocks float on a layer of denser rock.
1872 -–Fault lines proposition
Grove Gilbert figured out that earthquakes are centred around fault lines.
1889 – Seismometer detection
For the first time, a seismometer (in Germany) detected an earthquake on the other side of the Earth (in Japan).
1897 – P-waves and S-waves
Richard Oldham realised that there were at least two types of seismic waves that travelled at different speeds. We know these now as P-waves and S-waves.
Earth waves
Seismic waves are waves that travel through or over Earth. They are usually generated by movements of the Earth's tectonic plates (earthquakes) but may also be caused by explosions, volcanoes and landslides. They can tell us much about the Earth's structure.
1904 – Atomic reactions
Ernest Rutherford claimed that the Earth is heated by atomic reactions.
1906 – New thinking about fault lines
After the most destructive earthquake in American history at San Francisco, Harry Reid suggested that earthquakes are the result of stresses built up along faults.
1909 – Probing inside the Earth
Andrija Mohorovicic realised that you could use seismic waves to probe the hidden Earth.
1912 – Continental drift
Alfred Wegener put forward the idea of continental drift. His theory was that the continents were once joined to form a giant supercontinent that he called Pangaea.
1914 – Earth's core estimated 7,000km
Beno Gutenberg used seismic waves to estimate the diameter of the Earth’s core as 7,000 kilometres – a size that is still thought to be correct.
1921 – Colliding supercontinents
Alexander du Toit suggested that mountains are formed by colliding continents. He also suggested that Pangaea divided into two supercontinents. He called the northern supercontinent Laurasia and the southern one Gondwana.
Tectonic plates
This animated video shows the movement of the tectonic plates that make up the Earth’s crust.
Starting 600 million years ago, watch continents form and break apart as the plates move. Pangaea the supercontinent, split up at about 220 million years ago into Laurasia and Gondwana both of which broke up again. Gondwana which comprised Australia, Antarctica (including New Zealand), India, Africa and South America started breaking up about 150 million years ago. Australia departed from the Antarctica group at around 50 million years and around 35 million years ago South America moved away leaving Antarctica to move towards its current position.
1930 – Convection and continental drift
Harry Hess proposed convection currents in the mantle as a mechanism for continental drift.
1931 – How much damage?
Guiseppe Mercalli created the Modified Mercalli Scale to measure earthquake damage, based on a scale originally made in 1902.
1935 – Measuring magnitude
Charles Richter and Beno Gutenberg developed a new magnitude scale for earthquakes, now known as the Richter Scale.
1936 – P-waves measure inner core
Inge Lehmann used data from P-waves to suggest the existence of an inner core to the Earth.
1961 – Monitoring earthquakes worldwide
A worldwide earthquake monitoring system was set up. Several systems now exist, including the Global Seismographic Network. They contribute to the understanding of plate tectonics and other Earth processes.
Late 1960s – Plate tectonics
The realisation that ocean floors behave differently to continents led to the theory of plate tectonics.
1995 – Discovering slow slips
First slow slip events noticed in Japan and Canada. These are helping to explain plate movement and stress build-up in subduction zones.
Slip deficit in the North Island
Slow slip events have occurred in Gisborne, Hastings, Wanganui, Ashurst, Dannevirke, and Paekākāriki. Some take a few days and others take many months.
1996 – Inner core movement
Xiaodong Song and Paul Richards, using P-waves, discovered that the solid inner core rotates freely within the fluid outer core and at a different speed to the rest of the Earth.
2002 – New Zealand’s slow slip
First slow slip events recorded in New Zealand.
Slow slip event – an animation
Slow slips are silent earthquakes that occur below the Earth’s surface over a large area, unlike traditional earthquakes we feel that occur in a relatively small region.
Before discovering slow slip events, earthquakes were thought to be the only way the Earth’s crust could relieve the pent-up stresses caused by the moving tectonic plates.
Scientists are now actively working to understand the relationship between slow slips and earthquakes. There is evidence of earthquake swarms accompanying some slow slip events, suggesting a slow slip may increase stress in surrounding areas and could push an already stressed fault closer to rupture. However, in other cases, slow slip events can relieve stress on a fault, and this might postpone an earthquake.
Understanding the relationship between slow slip events and earthquakes and the collation of slow slip data will enable better earthquake forecast modelling.
This animation is a visualisation of a slow slip event.
2016 – Rethinking hazards in plate boundary zones
Kaikoura's 7.9 earthquake was so complex and unusual that it is likely to change conventional seismic hazard models.
Learning from the past
Seismic engineering makes use of the latest technology, but some of its breakthrough ideas are based on knowledge of the ancient world. Dr Stefano Pampanin of Canterbury University explains how we can learn from buildings that are still standing after thousands of years.
Related content
Frank Evison was one of New Zealand’s esteemed scientists who was a pioneer in the field of earthquake prediction. During his lifetime, our understanding of earthquakes improved dramatically. Frank believed passionately that, as a scientist, he had a duty to society, and his dedication to producing a reliable method of earthquake forecasting continued until his death in 2005. See his life, work and how it changed scientific thinking in our heritage scientist profile and interactive timeline.
