DK - WOW! The Visual Encyclopedia of Everything

160

MEXICO CITY

1985

Mexico’s capital city

is built on the dried-

out clay bed of an

ancient lake. The

earthquake that hit

the city in 1985 made

the clay shake like

jelly, making the

shock waves six times

as destructive. More

than 400 multistorey

buildings in the city

were shaken to the

ground, and at least

9,000 people died.

ALASKA 1964

On 27 March 1964,

the Pacific Ocean

floor slid 20 m (66 ft)

beneath Alaska in a

few minutes, causing

a colossal earthquake.

So few people live

in this remote region,

however, that only

125 lost their lives.

CHILE 1960

The biggest earthquake ever

recorded struck Chile in 1960.

It reached 9.5 on the Richter

Scale, which was devised in

1935 by American scientist

Charles Richter as a way

of measuring earthquakes

using instruments called

seismographs.

SAN FRANCISCO 1906

The San Andreas Fault in California, USA, marks where the Pacific

plate is sliding past North America. San Francisco is built on the

fault line, and in 1906 the city was almost destroyed when

the fault slipped 6 m (20 ft) and triggered disastrous fires.

The vast rocky plates of Earth’s crust are always moving.

Where the plates meet, the movement causes earthquakes.

Frequent slight movement just causes tremors (shaking),

but often the rocks on each side of a plate boundary lock

together. The strain builds up, distorting the rocks until

the locked section gives way. The rock springs back, often

shifting several metres, and the shock of this can cause a

catastrophic earthquake.

EARTHQUAKES

160_161_Earthquakes.indd 160 10/01/19 2:26 PM