An earthquake is a sudden and unpredictable movement that takes place in the Earth, where brittle fracture of rock can occur. This abrupt motion releases accumulated energy (called stress by scientists) along a fault in the Earth; this is what generates the earthquake. Brittle fractures occur in the shallow portion of the Earth called the lithosphere, which consists of the crust and uppermost mantle. Brittle fracturing can also occur in old oceanic plates that have been subducted into the mantle. Deep earthquakes ranging from 300-700 km in depth all occur within old, cold oceanic plates that are located within the Earths mantle. For more information check: https://www.usgs.gov/faqs/what-earthquake-and-what-causes-them-happen?qt-news_science_products=0#qt-news_science_products

Earthquakes mainly happen as a result of the movement of Earth's tectonic plates. Earthquakes, however, may also be caused by volcanic activity as well as induced by human activity, primarily by wastewater injection wells. The lithosphere, the brittle portion of the Earth's crust and uppermost mantle, is fractured in plates that are known as tectonic plates that move about the Earth over time due to mantle convection (process by which the Earth is cooling). http://redsismica.uprm.edu/English/education/images/structure.gif. As these tectonic plates move, they may separate, clash against each other, or move laterally past one another. Earthquakes in the Puerto Rico and Virgin Islands region are predominately produced from the interaction of the North American Plate with the Caribbean Plate. https://www.usgs.gov/faqs/what-earthquake-and-what-causes-them-happen?qt-news_science_products=0#qt-news_science_products

Magnitude is the measure of the size of an earthquake based on the amount of energy released by it. It's based on the records obtained by the seismometers. The concept of magnitude was first developed in 1935 by Dr. Charles Richter. The Richter magnitude scale was developed for local earthquakes recorded on Wood-Anderson seismometers in California. Today, scientists use a more sophisticated scale called Moment Magnitude to determine the size of significant earthquakes, as this new scale directly relates the amount of energy released by the earthquake to the physical properties of the fault. On the magnitude scale, each increase of a complete number translates into 32 times more energy.

https://www.usgs.gov/faqs/how-are-earthquakes-recorded-how-are-earthquakes-measured-how-magnitude-earthquake-determined?qt-news_science_products=0#qt-news_science_products

Earthquake intensity is a subjective measure that determines the impact of an earthquake on people and structures. To measure intensity, scientists use the Modified Mercalli Scale (MM), that goes from I-XII, where I mean it was registered on the seismometers but not felt by people, and XII means the total collapse of structures. https://earthquake.usgs.gov/learn/topics/mercalli.php

By definition, aftershocks are of the same or lower magnitude than the main earthquake. An aftershock occurs in the same region as the main event. Aftershocks are generated by the displacement of the plates when they're adjusting and getting to their point of equilibrium after the main shock. These aftershock sequences can further damage and/or collapse structures that have already been damaged by the major event. If the earthquake is of high magnitude, it is very likely that it will continue generating aftershocks for a long time, even years. This phenomenon is common in seismically active areas.

No. It is determined that animals have a strange behavior before a seismic event occurs because they have sharper senses and can detect seismic waves from the ground before us humans. Their change in behavior it's not a reliable factor because it's still not known for sure that the nature of said behavior is precisely caused by an earthquake, since it could be caused by a flood, hurricane, fire, or other natural phenomenon. https://www.usgs.gov/faqs/can-animals-predict-earthquakes

Earthquakes happen without warning and can be so violent that they don't let people run nor crawl, for it will tumble you down to the ground wherever you are. "Dropping, Covering, and Holding On" will give you a better opportunity for protecting yourself during an earthquake, even during quakes that make furniture move between rooms and even in buildings that could ultimately collapse. Dropping, covering your head (and the body under a strong table if it's possible), and holding onto furniture (even if it's moving) offers you better level of protection in most situations. The triangle of life proposes that dropping next to a large object so that, if an object falls, it will form an angle or a free space which would serve as protection. The scenario used to determine this method was an implosion, which doesn't represent the earth's movements caused by an earthquake. Studies of injuries and deaths from earthquakes since the past decades indicate that is more likely to be injured by objects that may fall or are thrown into the air (televisions, lamps, glass, bookshelves, etc.) than dying in a collapsed building. The technique of "Dropping, Covering and Holding On" will protect you against most injuries.

http://www.earthquakecountry.org/dropcoverholdon/

A lot of people may think that the occurrence of many small earthquakes could prevent the chance of a major one happening. The magnitude scale is logarithmic; every unit of magnitude is about 30 times larger than the unit before it. Which means, ~30 earthquakes of magnitude 3.0 are required to release the energy of an earthquake of magnitude 4.0. Therefore, to release the energy of an earthquake of magnitude 7.0, it would require a million earthquakes of magnitude 3.0. Small earthquakes release some of the energy from the fault, but it doesn't mean they'll prevent a large earthquake from occurring.

In Puerto Rico, we are surrounded by seismic faults, which are areas where the greatest number of earthquakes occur. To the north we have The Puerto Rico Trench and the 19°N Fault Zone, to the east we find the Sombrero Seismic Zone and the Anegada Passage, to the south the Muertos Trough, and to the west the Mona Passage, Mona Canyon, and the Septentrional Fault. Consequently, all of Puerto Rico is prone to earthquakes. Additionally, on land there are the Great Northern Puerto Rico Fault Zone and the Great Southern Puerto Rico Fault Zone. For more information, visit: http://redsismica.uprm.edu/Spanish/educacion/terremotos/sismicidad.php (look for another link since the English version isn't updated -> http://redsismica.uprm.edu/English/education/earthquakes/prediction.php)

The number of earthquakes in Puerto Rico hasn't increased in the last few years. The Puerto Rico Seismic Network has made improvements, including modernizing seismic monitoring equipment and automatic detection systems, as well as adding new stations to the network to detect small, commonly unfelt earthquakes, which previously went undetected. Nowadays, the increased access to different sources of information such as TV, radio, newspaper, and social media, keeps the public better informed about any geologic event that happens both in our region and the rest of the world.

It's the occurrence of a set of earthquakes of similar magnitudes in the same general area, without the occurrence of a major event of greater magnitude. At the Puerto Rico Seismic Network a few swarms a month are often detected as part of the normal seismic activity in the region.

NO. Earthquakes cannot be predicted. Despite the efforts of many scientists such as geologists, physicists, mathematicians, engineers, biologists, and other specialists to date, it hasn't been possible to predict the location, time or magnitude (size) of an earthquake in a specific region. https://www.usgs.gov/faqs/can-you-predict-earthquakes?qt-news_science_products=0#qt-news_science_products

There isn't a known connection between weather conditions and earthquakes. Earthquakes are the result of physical processes within the earth and may occur during sunny or rainy weather, summer or winter, temperate or tropical regions, etc. Earthquakes originate miles below the earth, out of reach of weather conditions or its changes, such as pressure, winds and clouds that only affect the surface of the Earth. https://www.usgs.gov/faqs/there-earthquake-weather?qt-news_science_products=0#qt-news_science_products

Some shallow cracks are formed during earthquakes and these can lead to landslides or land settlements. Now, faults don't open during an earthquake. None of these swallow people or the buildings. The movement of the fault occurs along its own plane. If the fault separated then there wouldn't be an earthquake, as there would be no friction between them. https://www.usgs.gov/faqs/can-ground-open-during-earthquake?qt-news_science_products=0#qt-news_science_products

When two plates move towards each other they cause a collision. If the collision is continuous, the denser layer slides (subducts) below the other one, being pushed into the Earth's mantle. The largest magnitude earthquakes on record occur in subduction zones. As such, the most powerful event recorded by instruments was a 9.5 Moment magnitude earthquake that occurred on May 22, 1960 in Chile. In our region, subduction occurs between the Caribbean plate and the North American plate; the denser North American Plate is subducting beneath the lighter Caribbean plate. The resulting clash between these plates is the main cause of many earthquakes that impact the Island.

It happens when the plates separate from one another. The separation creates a gap which allows hot, new material from the mantle to rise upwards. The combination of the hot material with the decrease of pressure as the material moves upwards generates melt (aka magma). When this melt reaches the surface, it generates basalt lava flows that fill in the gap created by the separating plates. In oceans, these boundaries appear as mid-ocean ridges such as the Mid-Atlantic Ridge. On land, these boundaries generate rift valleys such as the East African Rift Valley.

It happens when two tectonic plates slide laterally next to each other, along a fault. In this case there are no separations or collisions, but there are intense frictions along the fault. Both plates move laterally, like in the San Andreas Fault in California. In these zones, earthquakes can be strong, historically reaching up to magnitude 8.