Seismology Group 1 PDF

Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Poly...

Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter “GROUP 1” Specific Objectives Seismology Origin of Earthquakes Causes of Earthquakes Types of Earthquakes Seismology - is the scientific study of earthquakes and the propagation of elastic waves through the Earth. - Seismology came from two ancient Greek words “seismos” and “logos”. Seismos means earthquake while logos means science. Seismologist - The one who study about seismology. - Not only study the earthquakes as they happen, but also try to create models to predict when and where might occur. They also the effects of earthquakes, like seismic waves and tsunamis. FAMOUS SEISMOLOGISTS Charles Francis Richter (1900-1985) Developed Richter Scale, to measure the magnitude of earthquakes. He believe that the " The magnitude value was proportional to the logarithm of amplitude of the strong wave during an earthquake" (Matter Project, 1999. Developed Richter Scale in 1953, a device used to measure the magnitude of earthquakes.  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter The Richter Scale has been in use for many years and is an example of a logarithmic scale. Logarithmic scales are linear scales in 'x' such as 1.0, 2.0, 3.0 etc, but they represent magnitude changes of 10, 100 and 1000. Inge Lehmann (1888-1993) Who made a ground breaking discovery of the structure of the earth's core. She analyzed how energy release from earthquake travel through the earth. A Danish seismologist who made a ground breaking discovery of the structure of the earth's core in 1936 SEISMIC WAVES: - Seismic wave is a mechanical wave of acoustic energy that travels through the Earth caused by earthquake. - Earthquakes are caused by the sudden release of energy, producing waves that causes the movement of the earth. Those waves are called Seismic waves. - There are two types of Seismic waves the body waves and the surface waves. The body waves travels internally through the body of the earth that is why it is called body waves. The surface waves spreads across the surface of the earth. Body waves [Primary(P) waves, Secondary(S) waves] Primary(P) waves Secondary(S) waves  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter There are 2 types of waves under body waves. P-waves A.K.A. Primary waves - faster than the S-waves and causes the earth to move forward and backward or it compresses and expands the earth. S-waves A.K.A secondary/shear waves - causes the earth to moves up and down or in a shearing movement. Surface waves [Love wave, Rayleigh Wave] Love wave Rayleigh Wave There are 2 types of waves under surface waves. Love waves - causes the earth to move side to side perpendicular to the direction of the wave Rayleigh waves - causes the earth to move in a rolling circular motion ORIGIN OF EARTHQUAKES Earthquake - any sudden shaking of the ground caused by the passage of seismic waves through Earth's rocks Focus (Hypocenter) - the point on the fault where rapture occurs and the location from which the seismic waves are released Epicenter - the point on the Earths surface that is directly above the focus, the point where the earthquake originated  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter An earthquake is a natural phenomenon caused by the sudden release of energy in the Earth's crust, which creates seismic waves. 1. Focus (Hypocenter): This is the point inside the Earth where the earthquake originates. It's the location where the fault starts to slip. 2. Epicenter: The i the Earth's surface directly above the focus. This is often where the effects of the earthquake are most strongly felt. 3. Fault: A fracture or zone of fractures between two blocks of rock. The movement along the fault causes the earthquake. Common types of faults include normal, reverse (thrust), and strike- slip. 4. Seismic Waves: These are waves of energy that travel through the Earth. They include: - Primary Waves (P-waves): These are compressional waves that travel fastest and arrive first. They move through solids, liquids, and gases. - Secondary Waves (S-waves): These are shear waves that move slower than P-waves and arrive second. They move only through solids. - Surface Waves: These travel along the Earth's surface and usually cause the most damage. They include Love waves (which move horizontally) and Rayleigh waves (which create a rolling motion).  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter 5. Aftershocks: These are smaller earthquakes that occur in the same region after the initial earthquake as the Earth's crust adjusts. 6. Foreshocks:These are smaller tremors that can precede the main earthquake. They may occur days or even years before the main event. 7. Seismograph: An instrument used to detect and record the seismic waves produced by earthquakes. It helps in determining the magnitude and location of the quake. Understanding these components helps in studying earthquakes and mitigating their impact. Causes of Earthquakes Earthquakes are natural phenomena that occur when the Earth's surface experiences sudden and intense shaking due to the release of energy stored in its crust. These tremors can have devastating impacts, from minor vibrations to significant destruction. The causes of earthquakes can be categorized into natural and human-made factors. These are the major causes of earthquakes: VOLCANIC ACTIVITY When boiling lava tries to break through the surface of the earth, with the increased pressure of gases, certain movements are caused in the earth’s crust - When magma rises to the Earth's surface, it creates pressure that can lead to volcanic eruptions, causing the surrounding ground to shake. These volcanic tremors are often localized around the volcano.  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter TECTONIC MOVEMENT The surface of the earth consists of some plates, consisting of the upper mantle. These plates are always moving, thus affecting the earth’s crust. - The Earth's crust is made of large plates that constantly move. When these plates collide, pull apart, or slide past each other, the accumulated stress is released as seismic energy, resulting in an earthquake. Geological Faults A geological fault is known as the displacement of plates of their original plane. The movement of rocks along these planes brings about tectonic earthquakes. - Fault lines are fractures in the Earth's crust where sections of rock have moved. When stress builds up along these faults, it can lead to sudden movements that cause earthquakes. Man-Made The interference of man with nature can also become a cause of the earthquakeNuclear bombing can send specific types of shockwaves throughout the surface of the earth, which can disturb the natural alignment of tectonic plates - Man-Made Causes: Human activities such as mining, drilling, or constructing large reservoirs can induce seismic activity by altering the Earth's natural stress balance, leading to minor or significant earthquakes.  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter Minor Causes Some minor causes such as landslides, avalanches, the collapse of heavy rocks, etc. can also cause minor shockwaves. The gases beneath the surface of earth contract and expand, giving rise to movements in plates beneath the crust. - Natural events like avalanches, landslides, and even large-scale rockfalls can cause the ground to shake, but these tremors are generally less severe and more localized. Types of Earthquakes Causes of Earthquakes from which these are the underlying reasons why earthquakes occur. While these types of earthquakes refer to the different ways earthquakes can manifest based on their causes or characteristics., specifically the 4 types of earthquakes: tectonic, volcanic, explosion and collapse. These natural phenomena can have devastating consequences, but understanding their causes and characteristics can help us better prepare and respond to them. Tectonic Earthquakes - Earthquakes caused by tectonic plates are called tectonic quakes. These are the most occurred earthquakes worldwide and usually occur at the boundaries of the tectonic plates - These are caused by the sudden release of energy stored in rocks deformed by tectonic forces. Earthquakes caused by tectonic plates are called tectonic quakes. These are the most occurred earthquakes worldwide and usually occur at the boundaries of the tectonic plates. Examples of Tectonic Earthquake: San Francisco earthquake of 1906. The devastating quake, caused by the San Andreas Fault, destroyed much of the city.  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter Tohoku earthquake of 2011 in Japan. This powerful quake triggered a devastating tsunami, highlighting the interconnectedness of these natural disasters. And the very latest earthquake was happened in the offshore eastern Mindanao of the southern Philippines on August 3, 2024 resulted from renewed movement of an extinct fracture zone subducting into Earth’s mantle. Volcanic Earthquakes - caused by the movement of magma beneath the Earth’s surface. Occur in conjunction with volcanic activity, usually preceding or following a volcanic eruption. - These earthquakes are associated with volcanic activity, often indicating that magma is on the move beneath the surface. Caused by the movement of magma beneath the Earth’s surface. Occur in conjunction with volcanic activity, usually preceding or following a volcanic eruption. Examples of Volcanic Earthquake: The 1991 eruption of Mount Pinatubo in the Philippines was preceded by a series of volcanic earthquakes. These quakes served as a warning sign, allowing for evacuations and preparations.  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter The Department of Science and Technology-Philippine Institute of Volcanology an Seismology (DOST-PHIVOLCS) reported a sudden phreatic eruption at Mayon Volcano at 6:16 p.m. on July 18, 2024. Explosion Earthquakes - These earthquakes result from the explosion of chemical and nuclear devices. It can be measured by the motion of large tectonic earthquakes using a GPS device because the rocks on either side of the fault are offset during this type of earthquake - These are triggered by human activities, such as mining, reservoir-induced seismicity (due to large dams), or hydraulic fracturing commonly known as fracking, is a technique used to extract oil and natural gas from deep underground rock formations thru drilling and extraction - Whereas explosion earthquakes are immediate and result from a sudden, intense release of energy. - Induced earthquakes and explosion earthquakes are not the same, though they can both be caused by human activities. Example of Explosion Earthquake: The atomic bombings of Hiroshima and Nagasaki, marking the end of World War II, demonstrate the devastating power of nuclear weapons. These were the only instances of atomic bombs used in conflict, causing unimaginable destruction. The tests of nuclear bombs. For instance, the underground nuclear tests conducted by various countries, such as the tests at the Nevada Test Site in the United States, caused small earthquakes. The powerful explosions generated seismic waves similar to natural earthquakes.  Republic of the Philippines CAMARINES SUR POLYTECHNIC COLLEGES Nabua, Camarines Sur PHILIPPINE INSTITUTE OF CIVIL ENGINEERS Camarines Sur Polytechnic Colleges Student Chapter Collapse Earthquakes - Collapse earthquakes are compelled by the pressure produced within the rocks. This kind of earthquake leads to the collapse of the roof of the mines compelling more tremors. - Occur when a cave or underground mine collapses, causing the ground above to shake. - Example of Collapse Earthquake: One example of a collapse earthquake occurred in the Sichuan region of China in 2008. This 7.9 magnitude earthquake was caused by the collapse of mountains around the Wenchuan region. The earthquake left more than 69,000 people dead or missing and damaged thousands of buildings and infrastructure. It also caused landslides and flooding that threatened the safety of local communities. GROUP 1 (Reporters/Discussants) Abayog, Lenard Bermejo, Mark Dennis Bolo, Marlo Regaspi, Samuel Simara, Danilo III Vargas, Neil Christian (PowerPoint Presentation) Jacob, Kent Justin C. (Content/Data) Balana, Mark Edlian M. Llagas, Angelika Ortega, Loriemie Pontillas, Rica Joy