1. Frequency, regularity and predictability of earthquake hazard events
Seismic hazards
Frequency, regularity and predictability of earthquake hazard events

2. Average annual losses from natural disasters 1973 - 1997
Earthquakes are very dangerous!

6. Is it possible to predict earthquakes?
Attempts at prediction and warning include:
modern seismometers
unusual animal behaviour
changes in groundwater chemistry
seismic gap theory
There is as yet no reliable way of predicting earthquakes in terms of when and where. However people need to be prepared and to be prepared people need to know what to prepare for.

8. Seismoscope
132AD Zhang Heng’s seismoscope. Eight dragons attached to side of a bronze jar. Toads below each dragon. Bronze ball in each dragon’s mouth - drops into toad’s mouth when mechanism inside jar shaken by seismic waves. Click on image for animation on internet.

9. Seismometer
Seismometers are very sensitive instruments which measure ground motion including shaking caused by seismic waves. Use electronic sensors, amplifiers and recording devices. Data is sent in digital form back to a computer.

10. Animal behaviour
For thousands of years people have reported unusual animal behaviour shortly before large earthquakes.
Sichuan earthquake (2008) magnitude 7.9 nearly 70,000 dead million homeless 100 schools collapsed
Thousands of frogs crossed a road close to the earthquake epicentre three days before the earthquake.
Not yet understood why. Could be linked with changes in the Earth’s magnetic field linked with changes in rock structure at the atomic level.
Haicheng, China (1975) city (population ~ 1 million) evacuated 5.5 hours before a large earthquake magnitude ,000 people saved. Evacuation advised following warning signs including unusual animal behaviour and foreshocks.

11. Changes in groundwater chemistry
For several decades scientists have suspected that ground water changes its chemistry before an earthquake. Observed at Kobe A more systematic study conducted at Húsavik in Iceland - groundwater chemistry sampled every week from an artesian well. Found that hydrogen and sodium levels in the water significantly increased six months before a 5.6 magnitude earthquake in 2012 and again before a 5.5 magnitude earthquake in 2013.

12. Seismic gap theory
A seismic gap is a region along an active fault which is known to produce significant earthquakes and which has not moved in a long time. This means that a considerable amount of stress will have built up along that segment. Seismic gaps are considered to be the most likely locations to experience a large earthquake in the future. A series of moderate earthquakes may release the stored energy and make a large earthquake less likely.

13. Loma Prieta (USA) 1989
(About 380 miles between SF and LA) Loma Prieta earthquake occurred along a segment of the San Andreas fault system which had experienced significantly less seismic activity in previous decades.

14. Northern Anatolian fault in Turkey
Northern Anatolian fault 1500km long runs E-W across Turkey. Since 1939 earthquakes locations have moved west along the fault. Large earthquake at Izmit in 1999 magnitude km east of Istanbul. Stress has been building up along a 150km segment close to mega city Istanbul – vulnerable because high population, many old buildings not earthquake-resistant, high-rise buildings, lax building codes. Even a large magnitude 7.0 earthquake would cause significant damage. Stress could be released in a series of moderate earthquakes.