Earthquake Control Centre

control centre



The cities of Los Angeles and San Francisco are built on a significant fault line: the San Andreas seismic zone. The threat is therefore HIGH.  An affected city may be unable to rely on neighbouring communities for support in the first instance, as they too will be affected. So local emergency resources must be used selectively to prioritise areas of most need.  The emphasis of earthquake response will be directed towards saving the maximum number of lives and providing medical and welfare services to the survivors, until organised relief operations arrive.

Reports of earthquake damage are received and verified to direct emergency response.

Earthquakes produce all or some of the following:
Dead and injured persons, trapped persons, extensive building damage, extensive disruption to services and facilities, fire, evacuation and displacement of persons, disruption to traffic due to roadway and bridge failure, landslides.  To assess the level of damage, the Mercalli Scale is used to sort reports coming in from eyewitnesses in different localities.


You will assess the earthquake damage in different places, then send messages to Liaison Officers who will coordinate urgent rescue/medical responses according to priority need.

Resources for your homework, week beginning 16 October 2017:

First you need to understand the Mercalli Scale and how it is used. (This will be explained in the lesson before your homework.)  The Mercalli Intensity Scale contains DESCRIPTORS of earthquake damage. 

When a member of the public calls the Control Centre they are asked to describe their experience of the earthquake: what have they seen, heard, felt?  Then what they say is matched to one of the following descriptors and the INTENSITY of the earthquake IN THAT LOCATION is estimated.

I. Not felt.

II. Felt by persons sitting still indoors particularly on upper floors.

III. Felt indoors. Hanging objects swing. Vibration like passing of light trucks. May not be recognized as an earthquake.

 IV. Hanging objects swing. Vibration like passing of heavy trucks; or sensation of a jolt like a heavy ball striking the walls. Standing motor cars rock. Windows, dishes, doors rattle. Glasses clink. Crockery clashes. In the upper range of IV, wooden walls and frames creak.

V. Felt outdoors; direction estimated. Sleepers wakened. Liquids disturbed, some spilled. Small unstable objects displaced or upset. Doors swing, close, open. Lamp-posts swaying in the street. Shutters, pictures move. Pendulum clocks stop, start, change rate.

 VI. Felt by all. Many frightened and run outdoors. Persons walk unsteadily. Windows, dishes, glassware broken. Books, objects fall off shelves. Pictures off walls. Furniture moved or overturned. Weak plaster cracked. Small bells ring (church, school). Trees, bushes shaken (visibly, or heard to rustle).

 VII. Difficult to stand. Noticed by drivers of motor cars. Hanging objects quiver. Furniture broken. Damage to buildings, including cracks. Weak chimneys broken at roof line. Fall of plaster, loose bricks, stones, tiles, cornices (also unbraced parapets and architectural ornaments). Waves on ponds; water turbid with mud. Small slides and caving in along sand or gravel banks. Large bells ring. Concrete irrigation ditches damaged.

VIII. Steering of motor cars affected. Damage to brickwork and building fabric; partial collapse. Some damage to some buildings not to others. Fall of some building walls. Twisting, fall of chimneys, factory stacks, monuments, towers, elevated tanks. Frame houses moved on foundations if not bolted down; loose panel walls thrown out. Decayed piling broken off. Branches broken from trees. Changes in flow or temperature of springs and wells. Cracks in wet ground and on steep slopes.

IX. General panic. Building fabric destroyed and heavily damaged, sometimes with complete collapse; general damage to foundations. Frame structures, if not bolted, shifted off foundations. Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in ground. In alluvial areas sand and mud ejected from hillsides etc, earthquake fountains, sand craters.

X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted and flat land. Railway lines bent greatly. Underground pipelines completely out of service. Damage nearly total. Large rock masses displaced. Objects thrown into the air.

Homework TASK:

TITLE:    Mercalli Scale of Earthquake Intensity

Using the above 10-point scale, imagine you have been caught in an earthquake and you are phoning the Earthquake Control Centre with your report.  Somebody who had been in a location with an intensity V, for example, might say:

“I was woken because the bed was shaking and my clock fell off the bedside table.  It stopped when the clock smashed at three o’clock in the morning. I raced to the window and looked outside.  I could see the lamp posts in the street swaying with the shaking of the ground.  The shutters of the windows were knocking loudly against the wall of the house.  My brother came running into my room and said his books had fallen off the shelf and woken him up.  We did not go outside but stood in the door frame of my room, as we had been told to do, to stay safe.  The shaking stopped after two minutes.”

Using your imagination, now write four separate reports for intensities IV, VI, VIII and X