GEOLOGICAL ACTIVITIES

• Geological activities - basis of scientists in dividing lithosphere
• Earthquakes are not randomly scattered. they are located on the edges of plates or near water. there are no earthquakes to places far from the edges of plates.
• volcanoes are not randomly distributed. they are located on edges of plates. volcanoes are present where earthquakes are located
• volcanoes, mountains, and earthquakes are distributed near each other
• to compute the distance in finding the epicenter, use the formula

  d = time difference / 8 seconds * 100km
• 8 seconds is the interval between times of arrival of the P wave and S wave at a distance of 100km
• to find the scale in finding the epicenter, use this formula

  distance * 1.5 cm / 200km
• Triangulation Method - uses distance information from 3 seismic stations in order to locate the epicenter of earthquake.
• the method used to determine the depth of an earthquake is called Seismogram Analysis
• Geophysical Hazard Maps - includes places that are prone to earthquakes, disasters, and prone to hazards.
• Since 1968, PHIVOLCS has recorded 12 destructive earthquakes in the Philippines
• Seismology - study of earthquakes and seismic waves that move through and around the earth
• Seismologist - person who studies seismology
• Fault - the rupture and slippage along fractures of earth's crust which is caused by violent shaking of the earthquake.
• Manila trench involves La Union and Pampanga
• Philippine Trench involves Surigao del sur and Davao.