Cipong's Blog: The Biggest Earthquakes in Indonesia

Gempa Bumi Terbesar di Indonesia

10. 2009 Papua Earthquake
The 2009 Papua earthquake was a 7.6 Mw earthquake, which struck on January 4, 2009 at 04:43:51 local time (January 3, 19:43 UTC) killing at least four and injuring dozens of people, with an epicenter 150 kilometers (95 miles) west-northwest of Manokwari and about 170 km (105 miles) east-northeast of Sorong in Indonesia's West Papua province on the Bird's Head Peninsula. An official of World Vision said ten buildings had been totally destroyed, including several hotels and the house of a government official. Officials said three people, who had been staying at the Mutiara hotel in the city of Manokwari, were pulled alive from the rubble and taken to a hospital. Two hotels collapsed in the quake. There have been twenty-three aftershocks above magnitude 5.0, with one having a magnitude of 7.4 occurring at 07:33:42 local time (January 3, 22:33 UTC),[2] and another at magnitude 6.0. The earthquake was also felt in nearby Papua New Guinea and Darwin, Australia.
Japan's Meteorological Agency told Reuters news agency the earthquake also triggered a small 40 cm-high tsunami which hit the Japanese coast, but did not cause any damage.

9. 2009 Sumatra Earthquakes
The September 2009 Sumatra earthquake occurred just off the southern coast of Sumatra, Indonesia. The major shock hit at 17:16:10 local time on September 30, 2009 (10:16:10 UTC) and had a moment magnitude of 7.6. The epicenter was 45 kilometres (28 mi) west-northwest of Padang, Sumatra, and 220 kilometres (140 mi) southwest of Pekanbaru, Sumatra. Early death-toll estimates extended beyond 1300. Government reports have to date confirmed 1,115 dead, 1,214 severely injured and 1,688 slightly injured. The most deaths occurred in the areas of Padang Pariaman (675), Padang (313), Agam (80) and Pariaman (37).[2] In addition, around 135,000 houses were severely damaged, 65,000 houses were moderately damaged and 79,000 houses were slightly damaged.[2] An estimated 250,000 families (1,250,000 people) have been affected by the earthquake through the total or partial loss of their homes and livelihoods.

8. July 2006 Java Earthquake
The July 2006 Java earthquake was a magnitude 7.7 earthquake off the southwestern coast of Java, Indonesia. It occurred on July 17, 2006, at 08:24 UTC (15:24 local time).
The U.S. Geological Survey placed the epicentre of the quake at 9°17′42″S 107°20′49″E / 9.295°S 107.347°E / -9.295; 107.347, and its hypocentre at a depth of 48.6 km below the seabed.This is 225 km (140 miles) NE of Christmas Island, 240 km (150 miles) SSW of Tasikmalaya, Indonesia, and 358 km (222 miles) S of Jakarta, the capital and largest city of Indonesia.
According to the U.S. Geological Survey "The earthquake occurred as a result of thrust-faulting on the boundary between the Australia plate and the Sunda Plate. On this part of their mutual boundary, the Australia plate moves north-northeast with respect to the Sunda plate at about 59 mm/year. The Australia plate thrusts beneath the Sunda plate at the Java Trench, south of Java, and is subducted to progressively greater depths beneath Java and north of Java. The earthquake occurred on the shallow part of the plate boundary, about 50 km north of the Java trench."

7. September 2007 Sumatra Earthquakes
The September 2007 Sumatra earthquakes were a series of megathrust earthquakes that struck the Java Trench off the coast of Sumatra, Indonesia, three greater than magnitude 7. A series of tsunami bulletins was issued for the area. With a magnitude of 8.5, it is the fifth largest earthquake ever recorded on a seismograph.
The first earthquake occurred at 11:10:26 UTC (18:10 local time) on 12 September 2007, and was an 8.5 Mw earthquake on the moment magnitude scale. It was centered about 34 km underground, at 4°31′12″S 101°22′26″E / 4.520°S 101.374°E / -4.520; 101.374, about 130 km southwest of Bengkulu on the southwest coast of Sumatra, Indonesia, and some 600 km west-northwest of Indonesia's capital city, Jakarta. It was followed by several earthquakes of magnitude 5 through 6 along the same fault, west of Sumatra.
The second largest earthquake, 7.9 Mw,[4] occurred later the same day at 23:49:04 UTC (06:49:04 local time the following day). It was centred about 10 km underground, at 2°30′22″S 100°54′22″E / 2.506°S 100.906°E / -2.506; 100.906, some 185 km (115 miles) south-southeast of Padang, Indonesia and about 205 km northwest of Bengkulu (about 225 km northwest of the magnitude 8.5 earthquake).
After further aftershocks above magnitude 5, a third earthquake, 7.0 Mw,occurred at 03:35:26 UTC (10:35:26 local time) on 13 September. It was centred about 10 km underground, at 2°09′36″S 99°51′04″E / 2.160°S 99.851°E / -2.160; 99.851, some 165 km south-southwest of Padang and 345 km west-northwest of Bengkulu.
Aftershocks continued into 13 September and 14 September , with more earthquakes ranging up to magnitude 6.4. Most of the aftershocks have been northwest of the original magnitude 8.4 earthquake. A 6.7 struck Southern Sumatra on Sept 20, 2007.
Tidal buoys positioned in the Indian Ocean and other seismic tools have led scientists to issue a series of tsunami bulletins.
The tremors of the 8.5 Mw earthquake lasted for several minutes. It caused buildings to sway in Jakarta, and some buildings were reported to have collapsed in the city of Bengkulu, Province Bengkulu, about 100 km from the epicenter. Tremors felt in Jakarta were described as being "violent" It was reported that several high-rise buildings were evacuated. The earthquake also led to a power outage in Bengkulu, which crippled communications. The death toll of the earthquakes is 21 with 88 people injured.
Tremors were felt in neighbouring countries as far away as Southern Thailand.In Singapore, which is about 670 km from the epicenter, the tremor was felt at around 11:10 UTC (19:10 local time).Most of the Central and Eastern part of Singapore has felt the tremor. In Peninsular Malaysia, tremors were reported after 19:15 local time, including Kuala Lumpur, Putrajaya, Johor Bahru, Malacca and Penang. Like Singapore, the tremors were most severe on high-rises, resulting in minor panic and evacuations. No casualties were reported in the country, as of 13 September.

6. 2005 Sumatra Earthquake
The 2005 Sumatra earthquake, referred to as the Nias Earthquake by the scientific community, was a major earthquake on 28 March 2005, located off the west coast of northern Sumatra, Indonesia. Approximately 1,300 people were killed by the earthquake, mostly on the island of Nias. The event caused panic in the region, which had previously been devastated by the massive tsunami triggered by the 2004 Indian Ocean earthquake, but this earthquake generated a relatively tiny tsunami that caused limited damage. It was the 2nd most powerful earthquake since 1965.
The earthquake occurred at 16:09:36 UTC (11:09:36 P.M. local time) on 28 March 2005. The hypocenter was located at 2°04′35″N 97°00′58″E / 2.07639°N 97.01611°E / 2.07639; 97.01611, 30 kilometres (19 mi) below the surface of the Indian Ocean, where subduction is forcing the Indo-Australian Plate to the south-west under the Eurasian plate's Sunda edge. The area is 200 kilometres (120 mi) west of Sibolga, Sumatra, or 1,400 kilometres (870 mi) northwest of Jakarta, approximately halfway between the islands of Nias and Simeulue. Seismic recordings give the earthquake a moment magnitude of about 8.7, and effects were felt as far away as Bangkok, Thailand; over 1,000 kilometres (620 mi) away.
The earthquake lasted for about two minutes in total. In the twenty-four hours immediately after the event, there were eight major aftershocks, measuring between 5.5 and 6.0. A debate arose among seismologists over whether this should be considered an aftershock of the December 2004 event, or a "triggered earthquake" as it was larger than typical aftershocks but on the same fault.
On the Indonesian island of Nias, off the coast of Sumatra, hundreds of buildings were destroyed by the earthquake. The death toll on Nias was at least one thousand, with 220 dying in Gunungsitoli, the island's largest town. Nearly half of Gunungsitoli's population (27,000) fled the town.
The earthquake was strongly felt across the island of Sumatra, and caused widespread power outages in the Indonesian city of Banda Aceh, already devastated by the December 2004 tsunami, and prompted thousands to flee their homes and seek higher ground.
It was also strongly felt along the west coast of Thailand and Malaysia, and in Kuala Lumpur high-rise buildings were evacuated. The earthquake was felt less strongly in the Maldives, India, and Sri Lanka.

5. 1938 Banda Sea Earthquake
The 1938 Banda Sea earthquake occurred in the Banda Sea region on February 1, 1938, and was the ninth largest earthquake in the 20th century. It registered a magnitude of 8.5 on the Richter magnitude scale, and intensities as high as VII. It generated Tsunamis of up to 1.5 metres, but no human lives appear to have been lost.

4. 1797 Sumatra Earthquake
The 1797 Sumatra earthquake was the first in a series of great earthquakes that ruptured part of the Sumatran segment of the Sunda megathrust. It caused a damaging tsunami that was particularly severe near Padang, where a 150-200 ton English ship was driven 1 km inland up the Arau river.
The island of Sumatra lies on the convergent plate boundary between the Indo-Australian Plate and the Eurasian Plate. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust, and near pure strike-slip faulting along the Great Sumatran fault. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797, 1833, 1861, 2004 , 2005 and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during these larger events, in 1935, 2000 and 2002.

3. 1861 Sumatra Earthquake
The 1861 Sumatra earthquake occurred on February 16, 1861. It was the last in a sequences of earthquakes that ruptured adjacent parts of the Sumatran segment of the Sunda megathrust. It caused a devastating tsunami which led to several thousand fatalities. The earthquake was felt as far away as the Malay peninsula and the eastern part of Java. The rupture area for the 2005 Sumatra earthquake is similar to that estimated for the 1861 event.
The island of Sumatra lies on the convergent plate boundary between the Indo-Australian Plate and the Eurasian Plate. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust, and near pure strike-slip faulting along the Great Sumatran fault. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797, 1833, 1861, 2004 , 2005 and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during the larger events, in 1935, 2000 and 2002.

2. 1833 Sumatra Earthquake
The 1833 Sumatra earthquake occurred on November 25, 1833, about 22:00 local time, with an estimated magnitude in the range Mw= 8.8–9.2. It caused a large tsunami that flooded the southwestern coast of the island. There are no reliable records of the loss of life, with the casualties being described only as 'numerous'. The magnitude of this event has been estimated using records of uplift taken from coral microatolls.
The island of Sumatra lies on the convergent plate boundary between the Indo-Australian Plate and the Eurasian Plate. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust, and near pure strike-slip faulting along the Great Sumatran fault. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797, 1833, 1861, 2004, 2005 and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during the larger events, in 1935, 2000 and 2002.
There is only sparse information available regarding the extent of damage associated with either the earthquake or the subsequent tsunami. However, the tsunami was clearly devastating along the southwest coast of Sumatra from Pariaman to Bengkulu. There is also a lone report of significant damage in the Seychelles.

1. 2004 Indian Ocean Earthquake
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake. The resulting tsunami itself is given various names, including the 2004 Indian Ocean tsunami, Asian Tsunami, Indonesian Tsunami, and Boxing Day Tsunami.
The earthquake was caused by subduction and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing nearly 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 feet) high. It was one of the deadliest natural disasters in recorded history. Indonesia, Sri Lanka, India, and Thailand were the hardest hit.
With a magnitude of between 9.1 and 9.3, it is the second largest earthquake ever recorded on a seismograph. This earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes. It caused the entire planet to vibrate as much as 1 cm (0.4 inches)and triggered other earthquakes as far away as Alaska.
The plight of the many affected people and countries prompted a widespread humanitarian response. In all, the worldwide community donated more than $7 billion (2004 U.S. dollars) in humanitarian aid.
The energy released on the Earth's surface only, ME which is the seismic potential for damage, by the 2004 Indian Ocean earthquake and tsunami was estimated at 1.1×1017 joules or 26.3 megatons of TNT. This energy is equivalent to over 1502 times that of the Hiroshima atomic bomb, but less than that of Tsar Bomba, the largest nuclear weapon ever detonated. However, this is but a tiny fraction of the total work done MW (and thus energy) by this quake, 4.0×1029 ergs (40 ZJ), the vast majority underground. This equates to 4.0×1022 J, over 363,000 times more than its ME. This is a truly enormous figure, equivalent to 9,560 gigatons of TNT equivalent (550 million times that of Hiroshima), or about 370 years of energy use in the United States at 2005 levels of 1.08×1020 J.
The only recorded earthquakes with a larger MW were the 1960 Chilean and 1964 Alaskan quakes, with 2.5×1023 joules (250 ZJ) and 7.5×1022 joules (75 ZJ) respectively.
The earthquake generated a seismic oscillation of the Earth's surface of up to 20–30 cm (8–12 in), equivalent to the effect of the tidal forces caused by the Sun and Moon. The shock waves of the earthquake were felt across the planet; as far away as the U.S. state of Oklahoma, where vertical movements of 3 mm (0.12 in) were recorded. By February 2005, the earthquake's effects were still detectable as a 0.02 mm complex harmonic oscillation of the Earth's surface, which gradually diminished and merged with the incessant free oscillation of the Earth more than 4 months after the earthquake.
Because of its enormous energy release and shallow rupture depth, the earthquake generated remarkable seismic ground motions around the globe, particularly due to huge Rayleigh (surface) elastic waves that exceeded 1 cm in vertical amplitude everywhere on Earth. The record section plot below displays vertical displacements of the Earth's surface recorded by seismometers from the IRIS/USGS Global Seismographic Network plotted with respect to time (since the earthquake initiation) on the horizontal axis, and vertical displacements of the Earth on the vertical axis (note the 1 cm scale bar at the bottom for scale). The seismograms are arranged vertically by distance from the epicenter in degrees. The earliest, lower amplitude, signal is that of the compressional (P) wave, which takes about 22 minutes to reach the other side of the planet (the antipode; in this case near Ecuador). The largest amplitude signals are seismic surface waves that reach the antipode after about 100 minutes. The surface waves can be clearly seen to reinforce near the antipode (with the closest seismic stations in Ecuador), and to subsequently encircle the planet to return to the epicentral region after about 200 minutes. A major aftershock (magnitude 7.1) can be seen at the closest stations starting just after the 200 minute mark. This aftershock would be considered a major earthquake under ordinary circumstances, but is dwarfed by the mainshock.
Vertical-component ground motions recorded by the IRIS/USGS Global Seismographic Network
The shift of mass and the massive release of energy very slightly altered the Earth's rotation. The exact amount is not yet known, but theoretical models suggest the earthquake shortened the length of a day by 2.68 microseconds, due to a decrease in the oblateness of the Earth.It also caused the Earth to minutely "wobble" on its axis by up to 2.5 cm (1 in) in the direction of 145° east longitude, or perhaps by up to 5 or 6 cm (2.0 to 2.4 in). However, because of tidal effects of the Moon, the length of a day increases at an average of 15 µs per year, so any rotational change due to the earthquake will be lost quickly. Similarly, the natural Chandler wobble of the Earth, which in some cases can be up to 15 m (50 ft), will eventually offset the minor wobble produced by the earthquake.
More spectacularly, there was 10 m (33 ft) movement laterally and 4–5 m (13–16 ft) vertically along the fault line. Early speculation was that some of the smaller islands south-west of Sumatra, which is on the Burma Plate (the southern regions are on the Sunda Plate), might have moved south-west by up to 36 m (118 ft), but more accurate data released more than a month after the earthquake found the movement to be about 20 cm (7.9 in).Since movement was vertical as well as lateral, some coastal areas may have been moved to below sea level. The Andaman and Nicobar Islands appear to have shifted south-west by around 1.25 m (4.1 ft) and to have sunk by 1 m (3.28 ft).
In February 2005, the Royal Navy vessel HMS Scott surveyed the seabed around the earthquake zone, which varies in depth between 1,000 m and 5,000 m (3,300 ft and 16,500 ft). The survey, conducted using a high-resolution, multi-beam sonar system, revealed that the earthquake had made a huge impact on the topography of the seabed. 1,500-meter (5,000 ft) high thrust ridges created by previous geologic activity along the fault had collapsed, generating landslides several kilometers wide. One such landslide consisted of a single block of rock some 100 m high and 2 km long (300 ft by 1.25 mi). The momentum of the water displaced by tectonic uplift had also dragged massive slabs of rock, each weighing millions of tons, as far as 10 km (7 mi) across the seabed. An oceanic trench several kilometres wide was exposed in the earthquake zone.
The TOPEX/Poseidon and Jason 1 satellites happened to pass over the tsunami as it was crossing the ocean.[33] These satellites carry radars that measure precisely the height of the water surface; anomalies of the order of 50 cm (20 in) were measured. Measurements from these satellites may prove invaluable for the understanding of the earthquake and tsunami. Unlike data from tide gauges installed on shores, measurements obtained in the middle of the ocean can be used for computing the parameters of the source earthquake without having to compensate for the complex ways in which close proximity to the coast changes the size and shape of a wave.