Hazard Management in
Response to Earthquake
Occurrences :
Newcastle 1989 vs. Kobe 1995

Vivian Vu

Hazard Management in Response to Earthquake Occurrences - Newcastle 1989 vs. Kobe 1995

Characteristics of the Hazards
The Newcastle earthquake of 1989 is still, until this day, known as one of Australia’s most severe natural disasters. With the epicentre at Boolaroo, occurring roughly 15 kilometres west south west from the heart of Newcastle (32.967° S,
151.619° E), at the shallow depth focus of 10 kilometres, the earthquake hit 5.6 on the Richter scale. Although the duration only lasted around 5 to 6 seconds, the earthquake was felt in quiet a vast amount of area, stretching along the majority of the southern New South Wales coast, also reaching close to and along Victorian borders
(refer to figure 1). This is most likely the case as of the earthquake’s shallow depth focus, therefore it was able to be felt in areas such as Canberra and
Wollongong, and the capital of the state, Sydney.
It is believed that coal mining in the hunter region was a factor contributing to the cause of the quake, due to the human disturbance to tectonic activity.

FIGURE 1

Another major and disastrous earthquake of the 20th century was the Kobe earthquake in Japan, otherwise known as the ‘Great Hanshin’ earthquake. The epicentre occurred on the northern side of Awaji Island (34°45'N,
135°10'E), just 20 kilometres from Kobe. The focus of the earthquake was 22 kilometres, reaching an extremely destructive level of magnitude at 7.2 on the Richter scale. On the 17th of January, 1995, in the early hours of the morning at 5:46 a.m., the quake shook Kobe for a duration of 20 seconds. Although the earthquake was such a strong and catastrophic disaster, it was barely felt in the country’s capital, Tokyo, but felt in other main populated areas such as Osaka and Kyoto.

Frequency & Intensity
As Australia is a continent which does not sit on any major tectonic fault lines, the country is one to not be prepared for major damaging earthquakes. Although Australia is in the middle of the Indo-Australian plate, often portraying to people that it’s not a very seismically active area, earthquakes still occur due to convergence with the Eurasian and Pacific plates. This convergence causes stress to build up within the continental plate, resulting in fractures possibly occurring on the continent. This, along with tectonic disturbance due to coal mining, is what caused the Newcastle earthquake. It has been seen that previous earthquakes have occurred in Newcastle before, in the 19th century around 1840 and 1870, both with a magnitude of 5.3. The next noted earthquake in Newcastle was then the one recorded on 28th December 1989. The fact that this earthquake was not a oneoff, and was the most disastrous earthquake in Australia to date, the probability of the hazard reoccurring is likely. Although, as Australia does not lie on any tectonic fault lines, it is unlikely that the hazard is to cause catastrophic damage including many deaths and injuries.The intensity of the earthquake rated VIII - Destructive on the Mercalli Intensity Scale (refer to bottom right hand corner of figure 1), which is relatively intense for an Australian earthquake but not compared to places like Japan where constant seismic activity occurs.
Japan is a country which is constantly at the exposure of hazards such as earthquakes. This is due to their situation between all three converging plates of the Eurasian, Philippine and Pacific plate (refer to figure 2). As they lie on top of this area, the frequency of earthquakes is extremely high. They are situated in an area which is also known as the ‘Pacific Ring of Fire’ border, where most of the worlds hazardous tectonic activity is occurring to create volcanoes, earthquakes, tsunamis, trenches and more geomorphic hazards. Japan’s earthquakes are caused by the tectonic process of convergence, where two or