Earthquakes

Magnitude: 3.3

Location: N of Koorda, WA

Lat / Long: -30.619, 117.456

Date / Time: 18 May 2013 @ 01:11:06 (AEST)

Depth: 4 km

Damage: None reported

Tremor Radius: 31 km

Last update: 23 May 2013

Source: Geoscience Australia

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There are on average 80 earthquakes of magnitude 3.0 or more in Australia each year. Earthquakes above magnitude 5.5, such as the 5.6 magnitude event in Newcastle in 1989, occur on average every two years. About every five years there is a potentially disastrous earthquake of magnitude 6.0 or more.

World Seismic Monitor
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The table below lists earthquakes that occurred within or along the Indo-Australian Plate during the last 7 days.

It covers Australia, the Pacific Islands, New Zealand and as far as Jakarta, Indonesia. It only reports magnitude 4.5 tremors or greater.

Latest USGS Earthquake ShakeMaps

Earthquakes in the Brisbane Area

Seismic activity occurs in the Brisbane region but generally at such a low level that there is little to no community impact. Less than 10 minor earthquakes have been felt in the city since its founding, some 180 years ago. The largest of these, a magnitude 4.4 event occurred at Mt Glorious on 11 Nov 1960. It caused minor damage and was felt throughout the Brisbane area. That earthquake was enough to rattle windows and crockery but not enough to do any structural damage to buildings in the region.

On 15 December 2002, an earthquake occurred at 11.39pm. Centered under Ferny Grove in the north western suburbs of Brisbane, the event measured 3.0 on the Richter scale (depth 5km) it was felt by many residents. The earthquake woke people who heard loud noises and felt some movement.

A notable earthquake of approximate magnitude 4 was recorded at The University of Qld seismograph station in Brisbane, on 25 October 2000 at 03:43 pm. It was located 193 km offshore from Brisbane.

A magnitude 2.9 event was recorded at Acacia Ridge (about 15 km south of Brisbane city) on 18 July 1996. It was widely felt in Brisbane's southern suburbs and in Logan.

Close to Brisbane, the "Rosewood Earthquake" (Mag 3.2) occurred in 1988 and was felt through out the Brisbane River Valley. No damage was reported.

Australia Earthquake Map
This map depicts areas of Australia which are more or less susceptible to earthquakes Image not available

Since 1950, Australia has experienced 168 earthquakes above magnitude 5.0 and in 2011 there were 82 events recorded at magnitude 3.0 or above

What is an Earthquake?

An earthquake is the shaking and vibration at the surface of the Earth caused by underground movement along a fault plane or by volcanic activity.

The size of earthquakes is determined by measuring the amplitude of the seismic waves recorded on a seismograph. A formula is applied to these which converts them to a magnitude scale, a measure of the energy released by the earthquake.

For every unit increase in magnitude, there is roughly a thirty-fold increase in the energy released. For instance, a magnitude 2.0 earthquake releases 30 times more energy than a magnitude 1.0 earthquake, while a magnitude 3.0 earthquake releases 900 times (30x30) more energy than a magnitude 1.0.

A magnitude 8.6 earthquake releases energy equivalent to about 10,000 atomic bombs of the type developed in World War II.

The effects of an earthquake depend on many factors, such as the distance from the epicentre and the local ground conditions. Generally, for locations near the epicentre, the following effects may be observed:

The Richter Scale

Richter Scale	Description	** TNT Equivalent	Effects	Frequency
Less than 2.0	Micro	2.7 kg	Micro earthquakes, not felt.	About 8,000 per day
2.0-2.9	Minor	480 kg	Generally not felt, but recorded.	About 1,000 per day
3.0-3.9	Minor	11 tons	Often felt, but rarely causes damage.	49,000 per year (est.)
4.0-4.9	Light	480 tons	Noticeable shaking of indoor items, rattling noises. Significant damage unlikely.	6,200 per year (est.)
5.0-5.9	Moderate	15 kilotons	Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings.	800 per year
6.0-6.9	Strong	340 kilotons	Can be destructive in areas up to about 160 kilometres (100 mi) across in populated areas.	120 per year
7.0-7.9	Major	10-15 megatons	Can cause serious damage over larger areas.	18 per year
8.0-8.9	Great	480 megatons	Can cause serious damage in areas several hundred kilometres across.	1 per year
9.0-9.9	Great	2.7 gigatons	Devastating in areas several thousand kilometres across.	1 per 20 years
10.0+	Massive	15 gigatons	Never recorded. Massive devastation across very large areas.	Extremely rare (Unknown)
The Yucatán Peninsula meteor impact 65 million years ago was estimated at magnitude 12.55 on the richter scale or equivalent to 100 teratons of TNT. The impact is widely accepted as causing the extinction of the dinosaurs. 1 kiloton = 1,000 tons, 1 megaton = one million tons, 1 gigaton = one billion tons, 1 teraton = one trillion tons

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The 10 Largest Recorded Earthquakes
Mag	Location	Year
9.5	Valdivia, Chile	1960
9.2	Pr. William Sound, Alaska	1964
9.1	Northern Sumatra	2004
9.0	Honshu, Japan	2011
9.0	Kamchatka Peninsula	1952
8.8	Maule, Chile	2010
8.8	Ecuador	1906
8.7	Rat Islands, Alaska	1965
8.6	Sumatra, Indonesia	2005
8.6	Assam, Tibet	1950

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