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Mercalli Intensity Scale
The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or strength of an earthquake — an event occurring at greater or lesser depth. (The "" scale is widely used.) The MMI scale measures intensity of shaking, at any particular location, on the surface. It was developed from Giuseppe Mercalli's Mercalli intensity scale of 1902. While shaking experienced at the surface is caused by the seismic energy released by an earthquake, earthquakes differ in how much of their energy is radiated as seismic waves. They also differ in the depth at which they occur; deeper earthquakes have less interaction with the surface, their energy is spread throughout a larger volume, and the energy reaching the surface is spread across a larger area. Shaking intensity is localised. It generally diminishes with dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake
An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. In its most general sense, the word ''earthquake'' is used to describe any seismic event that generates seismic waves. Earthquakes can occur naturally or be induced by human activities, such as mining, fracking, and nuclear weapons testing. The initial point of rupture is called the hypocenter or focus, while the ground level directly above it is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2012 El Salvador Earthquake
An tsunamigenic earthquake occurred on 26 August 2012 at 22:37 CST with an epicenter off the coast of Usulután, El Salvador. It measured 7.3 on the moment magnitude scale () and had a focal depth of . It was felt along the country's coast and in San Salvador, although there was no damage. Along the San Juan del Gozo Peninsula, a tsunami triggered by the shock left 40 people injured. Waves were measured with a maximum run-up of . The earthquake and tsunami was caused by a rupture on a subduction zone along the Middle America Trench. Tectonic setting A convergent plate margin extends along the west coast of Central America where two tectonic plates collide. Oceanic lithosphere of the Cocos plate subducts beneath the continental crust of Central America. This continental crust is part of the Caribbean plate. Subduction occurs along the Middle America Trench, and the Cocos plate moves towards Central America at an estimated per year. The subduction zone is seismically active ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Liquefaction
Soil liquefaction occurs when a cohesionless saturated or partially saturated soil substantially loses Shear strength (soil), strength and stiffness in response to an applied Shear stress, stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid. In soil mechanics, the term "liquefied" was first used by Allen Hazen in reference to the 1918 failure of the Calaveras Dam in California. He described the mechanism of flow liquefaction of the embankment dam as: The phenomenon is most often observed in saturated, loose (low density or uncompacted), sandy soils. This is because a loose sand has a tendency to Compressibility, compress when a force, load is applied. Dense sands, by contrast, tend to expand in volume or 'Reynolds' dilatancy, dilate'. If the soil is saturated by water, a condition that often exists when the soil is below the water table or sea level, then water fills the gap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2025 Istanbul Earthquake
On 23 April 2025 at , a 6.2 earthquake struck the Sea of Marmara, southeast of Marmara Ereğlisi, Tekirdağ Province, Turkey, near Istanbul. One person died of a heart attack, 359 others were injured and moderate damage was recorded across the Marmara Region. Tectonic setting Istanbul lies close to the western end of the North Anatolian Fault Zone (NAFZ), which is a right-lateral strike-slip fault zone, forming the northern boundary of the Anatolian plate. The Anatolian plate is being forced westwards relative to the Eurasian plate by the northward movement of the Arabian plate. It extends from the Gulf of Saros in the west to Karlıova in the east. The western end of the fault zone consists of two main strands, the northern of which runs through the Sea of Marmara. It began to form around 13–11 million years ago in the eastern part of Anatolia, propagating gradually westwards. The fault eventually reached the Sea of Marmara around 200,000 years ago. Before the discrete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2005 Nias–Simeulue Earthquake
The 2005 Nias–Simeulue earthquake occurred on 28 March off the west coast of northern Sumatra, Indonesia in the subduction zone of the Sunda megathrust. At least 915 people were killed, mostly on the island of Nias. It was among the top 10 most powerful recorded worldwide since 1900, with a magnitude of 8.6 that caused a relatively small tsunami. Damage ranged from hundreds of buildings destroyed in Nias to widespread power outages throughout the island of Sumatra. Following the mainshock, eight major aftershocks occurred ranging from 5.5 to 6.0 magnitudes. The earthquake occurred at 16:09:37 UTC (23:09:37 local time) on 28 March 2005. The hypocenter was located below the surface of the Indian Ocean, where subduction is forcing the Indo-Australian plate to the southwest under the Eurasian plate's Sunda edge. The area is west of Sibolga, Sumatra, or northwest of Jakarta, approximately halfway between the islands of Nias and Simeulue. Effects were felt as far away as Bangk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2009 Sumatra Earthquakes
The first of the 2009 Sumatra earthquakes () occurred on 30 September off the coast of Sumatra, Indonesia with a moment magnitude of 7.6 at . The epicenter was west-northwest of Padang, West Sumatra, and southwest of Pekanbaru, Riau. Government and authorities 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). In addition, around 135,000 houses were severely damaged, 65,000 houses were moderately damaged and 79,000 houses were slightly damaged. 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.http://www.reliefweb.int/rw/rwb.nsf/db900SID/EDIS-7WSKEP Tectonic setting Many of Indonesia's islands, including Sumatra, are situated within a zone of high seismic activity known as the Ring of Fire. Along the Sunda megathrust, the Indo-Australian plate is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2002 Hindu Kush Earthquakes
The 2002 Hindu Kush earthquakes struck in northern Afghanistan, with the two most destructive events striking during the month of March. At least 169 people were killed with a very large and intermediate-depth 7.4 event on March 3. Three weeks later, at least 1,200 were killed during a moderate but shallow 6.1 event that had a maximum Mercalli intensity of VII (''Very strong''). A 5.9 aftershock on April 12, which had a Mercalli intensity of VII (''Very strong''), killed an additional 50 people. The 7.4 and 6.1 reverse events were focused in the Hindu Kush mountain range area. Tectonic setting Northern Afghanistan lies within the broad zone of continuing collision between the Indian plate and the Eurasian plate. The area is seismically active, particularly as a result of faulting at just over 200 km depth within the descending slab. Many large events of M ≥ 7 have been observed in the Hindu Kush, all with similar epicenters, with an approximate periodicity of abou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
May 1998 Afghanistan Earthquake
An earthquake occurred in northern Afghanistan on May 30, 1998, at 06:22 UTC in Takhar Province, with a moment magnitude of 6.5 and a maximum modified Mercalli intensity of VIII (''Severe''). At the time, the Afghan Civil War was underway; the affected area was controlled by the United Islamic Front for the Salvation of Afghanistan (the "Northern Alliance"). Overview This earthquake was the second large earthquake in the area in 1998 after another earthquake on February 4. Between 4,000 and 4,500 people died in Takhar and Badakhshan provinces. Nearly 7,000 families were affected, and it was estimated that 16,000 houses were destroyed or damaged. Approximately 45,000 people became homeless. More than 30 villages were destroyed, and another 70 were severely damaged. Several thousand animals were killed, and crops and infrastructure were destroyed. Like many least developed nations, Afghanistan was ill-equipped to face this kind of natural disaster. The country had no forms of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2000 Enggano Earthquake
On 4 June 2000, at 23:28 WIB, southern Sumatra in Indonesia was struck by an earthquake of with a maximum Mercalli intensity of VI (''Strong''). The event occurred off the coast near Enggano Island. There were more than 100 fatalities and up to 2,585 injuries. Over 340 aftershocks shook the area throughout the rest of 2000, one just eleven minutes after the mainshock. This was the first and southernmost in a series of very large to great Sumatran earthquakes in the 2000s to rupture almost the entire western part of the Sunda megathrust, most notably including the 2004 Indian Ocean, 2005 Nias–Simeulue and 2007 Bengkulu earthquakes. Background and tectonics Indonesia is well known for strong earthquakes: the 2000 Enggano event marked the beginning of an ongoing period of seismic activity in the area, highlighted by the 2004 Indian Ocean earthquake. The 2000 Enggano earthquake took place at the southeastern end of the fault segment that ruptured during the 1833 Sumatra eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2021 West Sulawesi Earthquake
A Moment magnitude scale, moment magnitude () 6.2 earthquake struck Majene Regency in West Sulawesi, Indonesia, on 15 January 2021, at 02:28 Time in Indonesia, WITA (18:28 UTC). The reverse faulting shock initiated at depth with an epicenter inland, located south of Mamuju (city), Mamuju. It was preceded by a 5.7 foreshock several hours prior. Shaking from the mainshock was assigned a maximum Modified Mercalli intensity of VI (''Strong'') in Majene and Mamuju. Four of the five regencies in West Sulawesi were affected. More than 6,000 structures were damaged or destroyed; damage was estimated at Rp829.1 billion rupiah. At least 105 people were confirmed dead; nearly 6,500 were injured and thousands were displaced. Tectonic setting Sulawesi lies within the complex zone of interaction between the Australian plate, Australian, Pacific plate, Pacific, Philippine Sea plate, Philippine and Sunda plates in which many small microplates have developed. The main active structure onsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plaster Veneer
Plaster veneer (American English) or plaster skim (British English) is a construction methodology for surfacing interior walls, by applying a thin layer of plaster over a substrate—typically over specially formulated gypsum board base, similar in nature to drywall. History Until the mid twentieth century, it was standard practice in Western construction to surface interior walls using wooden lath and a layer of plaster about a half-inch thick ("lath and plaster"). Later, drywall became a standard. Typically, drywall is surfaced using the "mud-and-tape" method, where non-adhesive paper or mesh tape and drywall joint compound ("mud") is used to fill joints, cover nail heads, and repair any flaws. Plaster veneer was developed as a way of taking advantage of the reduced labor of modern drywall, while providing a genuine plaster surface for a wall. Applications In much of the world, plaster veneer is a very rare wall surface. Consequently, it can be difficult to find a local trade ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2010 Mentawai Earthquake And Tsunami
The 2010 Mentawai earthquake occurred with a Moment magnitude scale, moment magnitude of 7.8 on 25 October off the western coast of Sumatra at 21:42 local time (14:42 UTC). The earthquake occurred on the same fault that produced the 2004 Indian Ocean earthquake. It was widely felt across the provinces of Bengkulu and West Sumatra and resulted in a substantial localized tsunami that struck the Mentawai Islands. Tectonic setting The island of Sumatra lies above the Sunda megathrust, the interface between the Subduction, subducting Australian plate and the overriding Sunda plate. Movement on this structure has been responsible for many large historical megathrust earthquakes. The most recent sequence of large ruptures started with the 2004 Indian Ocean earthquake and included the 2005 Nias–Simeulue earthquake and the 2007 Sumatra earthquakes (other), 2007 Sumatra earthquakes. Earthquake The earthquake occurred around west of Bengkulu, close to the Mentawai Islands, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
