Mr. Longoria's Earth Science

The South American arc extends over 7,000 km, from the Chilean margin triple junction offshore of southern Chile to its intersection with the Panama fracture zone, offshore of the southern coast of Panama in Central America. It marks the plate boundary between the subducting Nazca plate and the South America plate, where the oceanic crust and lithosphere of the Nazca plate begin their descent into the mantle beneath South America. The convergence associated with this subduction process is responsible for the uplift of the Andes Mountains, and for the active volcanic chain present along much of this deformation front. Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 mm/yr in the south to approximately 65 mm/yr in the north. Although the rate of subduction varies little along the entire arc, there are complex changes in the geologic processes along the subduction zone that dramatically influence volcanic ac...

The April 1, 2014 M8.2 earthquake in northern Chile occurred as the result of thrust faulting at shallow depths near the Chilean coast. The location and mechanism of the earthquake are consistent with slip on the primary plate boundary interface, or megathrust, between the Nazca and South America plates. At the latitude of the earthquake, the Nazca plate subducts eastward beneath the South America plate at a rate of 65 mm/yr. Subduction along the Peru-Chile Trench to the west of Chile has led to uplift of the Andes mountain range and has produced some of the largest earthquakes in the world, including the 2010 M 8.8 Maule earthquake in central Chile, and the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile. Additional information on the northern Chile earthquake can be found at  USGS Summary of M8.2 Earthquake 2014 in Northern Chile .

Recent events in Haiti, have shown us the vast destruction and lost of life that a major earthquake causes. The 2010 Haiti earthquake was a catastrophic magnitude 7.0 Mw earthquake . Its epicenter was near the town of Léogâne , approximately 25 km (16 miles) west of Port-au-Prince , Haiti's capital. The earthquake occurred at 16:53 local time (21:53 UTC ) on Tuesday, 12 January 2010. By 24 January, at least 52 aftershocks measuring 4.5 or greater had been recorded. An estimated three million people were affected by the quake; news states that 200,000 people have been identified as dead and that an estimated 300,000 injured have been treated so far. It is also estimated that 250,000 residences and 30,000 comercial buildings have collapsed or severely damaged. Most earthquakes result from the strain that builds up at tectonic plate boundaries. More than 3 million earthquakes occur each year. Most of these are too small to be noticeable. Each year, however, a number of powerful e...

Earthquakes are measured using intensity and magnitude scales. The Mercalli scale measures the intensity of an earthquake based on the reports of people who experienced or observed the amount of destruction it caused. The most dependable measurements of earthquakes, however, are made with seismographs. Seismographic records of earthquakes have established magnitude scales. The Richter scale is one such magnitude scale. A seismograph records the magnitude of an earthquake and the time the seismic waves arrive. Seismologists use the difference in the speeds of P- and S-waves to locate the epicenter of earthquakes. Assignments : the Volcano Reports are due Monday, April 20, 2009. Homework # 10 : Due Thursday, April 23, 2009 In Review Book, read pages 54-58. Do questions 1-16 Welcome back! I hope everyone had a great spring break.