Figure 3 shows the high seismicity of West Sumatera. On the map shows that the density of seismicity of West Sumatera is more visible around the island of Nias (Zone 5), south of Siberut Island, around the Mentawai Islands (Zone 7), along the active fault zone of Sumatra and also in the subduction path. This high seismic density is thought to be influenced by tectonic activity owned by West Sumatra. These tectonic activities include subduction zones located in the western part of Sumatra Island stretching along its coastline, underwater active fault activities such as the Mentawai fault, and the activity of the Sumatran Fault. Most of the earthquakes caused by the subduction zone and the active fault zone of Sumatra are potentially large …show more content…
These three areas are seismic zones (regime stress) are quite dynamic and has the potential to cause significant and destructive earthquake. A region with a low-b value is an active seismic area that is still locked called a locked zone. Locked zone can someday bring significant and destructive earthquakes. Thus, areas with low-b values as mentioned above need to be aware of significant earthquakes. While areas with a high b-value as seen in the north of Nias Island are referred to as creeping zones, are active fault zones that do not experience energy accumulation and do not experience slippage. This is in accordance with previous research that low b-values are associated with rock stress conditions in the area high, and vice versa. [7]
The results of this observation are compared with observations in the period 1980-2016 (Syafriani, 2017: International Conference-Bali) shown in Figure 5 (a), it is found that the b-value in the period (1971-2017) is higher than the b-value in the period (1980-2016). The b-value in the period (1971-2017) is 0.956, while the b-value in the period (1980-2016) is 0.928. This is also indicated by the blue color in the southern island of Siberut (period 1980-2016) more concentrated than the blue color in the southern island of Siberut (period 1971-2017). The difference in this condition is suspected because the area around Siberut Island after 2016 has been
This lab uses earthquake data to construct profiles of two convergent boundaries: the Tonga Trench and the Peru-Chile Trench. Where two tectonic plates converge, if one or both of the plates is an oceanic lithosphere, a subduction zone will form. When crust is formed at a mid-ocean ridge, it is hot and buoyant meaning it has a low density. As it spreads away from the ridge and cools and contracts, or becomes denser, it is able to sink into the hotter underlying mantle. When two oceanic plates collide, the younger of the two plates, because it is less dense will ride over the edge of the older plate. The density of the
In conclusion the recent conception and development of plate tectonic theory has greatly aided our understanding of the distribution of seismic events. We now understand that there is a correlation between earthquakes/volcanoes locations and their proximity to a plate boundary plates are continually moving and earthquakes and volcanoes are found along these boundaries. Exceptions to this rule such as Hawaii also help prove tectonic theory due to their unique creation. Whilst this has helped our understanding we also recognise the fact those in LEDCs with poor access to education are unaware of plate tectonic theory so they cannot understand the hazards that some countries face, nor have the means to mitigate against them thus worsening the
The gravitational stress on the volcano flanks develops large-scale on-shore and off-shore sliding, related to the activity of the rift zones. The M=7.2 earthquake at Kilauea on 1975 was probably related to strain accumulated throughout the south flank from dikes intruded in the rift zone (Swanson et al., 1976). However, the earthquake itself resulted from abrupt southward movement of the south flank across the underlying oceanic crust, activating the Hilina-Pali fault system. Such faulting not only provides a means for the flanks to adjust continuously to intrusions, but also generates the stress patterns needed to constrain future dikes to propagate along the rift axis. Therefore, rift intrusion and lateral spreading are major contributors
According to the research report, it will cause thousands of people die, towns submerged, buildings and bridges damaged once a huge earthquake and tsunamis happened on the Pacific Northwest area near American coast. And losses will be estimated at over 5 billion dollar US dollars. This shocking article was composed by seismic safety advisory committee in Oregon. According to materials, a super-strong earthquake once happened in A.D. 1700 Cascadia Subduction Zone (CSZ) on the Pacific Northwest coast. There are some experts forecast that another super-huge earthquake will occur in the future. The report has shown that once the earthquake occurs, the regions from North California to British Columbia Coastal region will suffer devastation, cause heavy casualties. Water and electricity shortage issues definitely follow this heavy disaster, meanwhile, communication and heating system and gas supply will definitely broken off in the light of this earthquake. The CSZ is a 1,000 km long dipping fault that stretches from Northern Vancouver Island to Cape Mendocino in northern California. It separates the Juan de Fuca (Juan
• This earthquake may not have released all of the strain stored in its rocks next to the fault this reveals a potential earthquake in the Santa Cruz Mountains in the near future. The occurrence of the earthquake showed that the Earth did not exhaust all its strain and hence other earthquakes could be expected. However, the dates could not be predicted. The extent of the damage could have been much more devastating for the region, but with the earthquake occurring near the coast this made half of the felt area westward in the Pacific Ocean. The occurrence of aftershocks ten days later reinforces the unpredictability nature and hence makes Geology to be a study that is always evolving. In conclusion, the Earth and the study of cannot be exhausted as every natural occurrence provides a new puzzle to be solved.
The 1906 San Francisco Earthquake tectonic setting was in the outermost shell of earth known as the crust this is composed of rigid plates that have been moving for hundreds of millions of years. Two of these moving plates meet in western California; the boundary between them is a zone of faults, the principal one being the San Andreas fault. The horizontal sliding of the Pacific Plate relative to the North American Plate, causes earthquakes along the San Andreas fault and similar plates near the region. The San Andreas fault is a transform plate boundary, accommodating horizontal relative motions (usgs.gov).
The tectonic setting for the 1906 San Francisco Earthquake was in the outermost shell of earth consisting of rigid plates that have been moving for hundreds of millions of years. Two of these moving plates meet in western California; the boundary between them is a zone of faults, the principal one being the San Andreas fault. The Pacific Plate (on the west) slides horizontally northwestward relative to the North American Plate (on the east), causing earthquakes along the San Andreas and associated faults. The San Andreas fault is a transform plate boundary, accommodating horizontal relative motions (usgs.gov).
In recorded history, there have been 151 earthquakes in Nevada that were a magnitude of 3.5 or higher. As previously mentioned, the mountain ranges of Nevada are typically bound on one side or the other by a fault. There are quaternary faults that range in ages from less than 150 years to around 1.8 million years in existence. The property damage in Nevada from earthquakes was .2 million dollars between 1196 and 2014 based on information from department of energy for the state. As we studied in our textbook, earthquakes can by a number of things, such as shifting faults, or volcanic
A ‘hazard’ can be defined as a geophysical process operating within the lithosphere, atmosphere, hydrosphere or biosphere which could potentially lead to the loss of human life or property. However, an earthquake only becomes hazardous and therefore needs management if it occurs within close proximity to a vulnerable population. To some extent, any human settlement around the world situated close to or on top of an area of seismic activity is vulnerable. However, not all nations suffer equal devastation.
There are many dangers to an earthquake. Earthquakes can cause damage to cities and many people end up injured or dead. The shaking of the ground can cause mudslides and landslides.Earthquakes can also cause terrible tsunamis.Earthquakes can occur on convergent, divergent, and transform boundaries. They can also can occur on subduction zones. In this case, the earthquake occurred on a subduction zone. Subduction is the process of which the denser plate sinks under the less dense
The 9.0 magnitude Indian Ocean earthquake was caused by subduction under the Indian Ocean. Earthquakes are usually caused by convection currents leading to subduction/convergent currents. Convection currents is caused by magma rising from the deepest part of the earth, then slowly cooling, sinking again then re-heating, then rising upwards basically repeating the rising and cooling then re-heating cycle over and over again. The plates are separated from each other and they move apart, the plates then obviously hit another plate right next to it causing subduction. This earthquake was caused on the Oceanic crust, in the Indian Ocean, creating tsunamis that caused disasters and thousands of life loss throughout the Indian Ocean basin. The
Earthquake Hazards occur when there are adverse effects on human activities. This can include surface faulting, ground shaking and liquefaction. In this essay I will be discussing the factors that affect earthquakes, whether human such as population density, urbanisation and earthquake mitigation or physical such as liquefaction, magnitude, landslides and proximity to the focus.
Earthquakes pose a significant risk in many regions of the Sub-Saharan Africa (SSA), more particularly along the tectonically active East African Rift System (EARS). Further away from this rift system, the remainder of SSA is largely considered a stable intra-plate region characterized by a relatively low rate of seismicity. Nonetheless, several large earthquakes have been reported in historical times. While most of earthquakes in Sub-Saharan Africa occur along the EARS (inter-plate seismicity), it must be noted that a damaging earthquake can occur anywhere, especially as cities grow and many buildings are constructed without taking potential ground shaking into account. Even moderate-sized events can prove disastrous should it occur near
The San Andreas Fault is one of the most widely studied faults in the world. Scientists use an array of methods in collecting data and providing analysis of fault characteristics both past and present. Presently there are many differing hypothesis and models used to describe crustal movements and deformation within the Pacific and North American plate boundary. Historical earthquakes along this fault have proven to be rather large and devastating. This is important since the San Andreas Fault runs along many highly populated areas throughout Northern and Southern California. Through further research and analysis of this fault system scientists hope to solve
It’s recognized as the second deadliest earthquake in New Zealand following the 7.8 Hawkes bay Earthquake (Kaiser et al, 2012). The earthquake was first thought to be an aftershock of the 7.1 Darfield earthquake of September 2010 at the eastern edge. This was an area that originally was of a low earthquake occurrence rate since prior to 2011 there was no knowledge of a fault’s existence thus catching the New Zealand citizens off-guard. The Christchurch earthquake resulted in 185 casualties affecting more than 300,000 people (Kaiser et al, 2012). The earthquake first made contact with in the South Islands, only 10 km away from the center of Christchurch. Ground motions were unusually large near Christchurch measuring 2.2 g and 1.7g at the epicenter, the point directly above