Section 1
Plate Tectonics
1. The distance between Mount St. Helens and Loma Prieta, California are about 999km or 620 miles.
2. These two points reside near the North American Plate. The North American Plate covers most of North America, Bahamas, Cuba, Greenland and Iceland. It extends Eastward toward the Mid- Atlantic ridge and westward toward the Chersky Range, which is located in Eastern Siberia. The Plate consists of both continental and oceanic crust. The boundary along the gulf area of California is more complex since there is a Gulf California Rift Zone, an extension of the East Pacific Rise, which extends about 1300km from the Gulf of California to the San Andreas Fault. The red line on the image shows that its upper point is close to Loma Prieta, California. The Eastern Pacific Rise, is a mid-oceanic ridge that is located along the floor of the Pacific Ocean. It separates the Pacific Plate and the North American Plate.
The red line highlights the distance between Loma Prieta and the Gulf California Rift Zone.
The image below is an overview estimate outline of the North American Plate
The red line highlights the distance between Loma Prieta and the Gulf California Rift Zone.
The image below is an overview estimate outline of the North American Plate
3. Studies in the past suggest that most earthquakes and volcanic eruptions do not occur randomly and they are more predominant in areas along plate boundaries. Both Mount St. Helens and the Loma Prieta Earthquake zone reside along the North American Plate.
In March 1980, Mount St. Helens experienced a 4.2 magnitude earthquake and within a week, the steam started to vent from the volcano. On May 18th, a second earthquake occurred with a magnitude of 5.1, and that caused the collapse of the north side of the mountain and sparked the beginning of the massive eruption. There was also an earthquake in Imperial Valley California in October of 1979 with a 6.4 magnitude. The Imperial Valley is located near the Loma Prieta area. This could make for speculation that the Mount St. Helens earthquakes and the eruption could have caused a ripple effect along the North American Plate. Additionally, on May 25 and May 27 1980 Mammoth Lakes California experienced a 6.1 and 6.0 magnitude earthquakes. The area is about 980 km south of Mount St. Helens, also located near the Loma Prieta area.
The Loma Prieta area sits near the San Andreas Fault Zone which separates the Pacific Plate and North American Plate, causing a strike split fault. The Loma Prieta Earthquake of 1989 was a 7.1 magnitude. The area had not seen an earthquake near this magnitude since the San Francisco Earthquake of 1906. In October of 1989 the Loma Prieta earthquake occurred, and in June 1991 Mount Pinatubo, an active stratovolcano in the Philippines erupted. In June of 1990 there was an earthquake on Panay Island in the Philippines with a 7.1 magnitude.
These earthquakes and volcanic eruptions may suggest that there could be a link between the two. It does appear that when there are increased numbers of larger scale earthquakes that the active volcanoes in the area may be more prone to erupt. In the case of Mount St. Helens, there were a few prior to the eruption in nearby California, and there were multiple earthquakes within the same time period and up to a year to follow in California. Also, volcanic activity can also be linked to plate tectonic movement, and most of the world’s active above sea volcanoes are near convergent plate boundaries where subduction occurs, and Mount St Helens is in a subduction zone.
However, due to the distances between the two locations and the decade of elapsed time, it is difficult to determine if there is a relationship. Earthquakes and volcanoes have been reoccurring for centuries, and there is minimal evidence clearly defining the correlation between the two.
In March 1980, Mount St. Helens experienced a 4.2 magnitude earthquake and within a week, the steam started to vent from the volcano. On May 18th, a second earthquake occurred with a magnitude of 5.1, and that caused the collapse of the north side of the mountain and sparked the beginning of the massive eruption. There was also an earthquake in Imperial Valley California in October of 1979 with a 6.4 magnitude. The Imperial Valley is located near the Loma Prieta area. This could make for speculation that the Mount St. Helens earthquakes and the eruption could have caused a ripple effect along the North American Plate. Additionally, on May 25 and May 27 1980 Mammoth Lakes California experienced a 6.1 and 6.0 magnitude earthquakes. The area is about 980 km south of Mount St. Helens, also located near the Loma Prieta area.
The Loma Prieta area sits near the San Andreas Fault Zone which separates the Pacific Plate and North American Plate, causing a strike split fault. The Loma Prieta Earthquake of 1989 was a 7.1 magnitude. The area had not seen an earthquake near this magnitude since the San Francisco Earthquake of 1906. In October of 1989 the Loma Prieta earthquake occurred, and in June 1991 Mount Pinatubo, an active stratovolcano in the Philippines erupted. In June of 1990 there was an earthquake on Panay Island in the Philippines with a 7.1 magnitude.
These earthquakes and volcanic eruptions may suggest that there could be a link between the two. It does appear that when there are increased numbers of larger scale earthquakes that the active volcanoes in the area may be more prone to erupt. In the case of Mount St. Helens, there were a few prior to the eruption in nearby California, and there were multiple earthquakes within the same time period and up to a year to follow in California. Also, volcanic activity can also be linked to plate tectonic movement, and most of the world’s active above sea volcanoes are near convergent plate boundaries where subduction occurs, and Mount St Helens is in a subduction zone.
However, due to the distances between the two locations and the decade of elapsed time, it is difficult to determine if there is a relationship. Earthquakes and volcanoes have been reoccurring for centuries, and there is minimal evidence clearly defining the correlation between the two.
4. The human impact was much different for each of these incidents. The population for Loma Prieta is much denser than the area surrounding Mount St. Helens. Millions of people reside near the active fault zone of the San Andreas, the Loma Pierta Earthquake of 1989 was devastating to multiple cities in the area. There were collapsed buildings, uprooted streets, and damage seen in multiple cities. There were also a few deaths caused by falling debris. While the Mount St. Helens, experienced earthquakes, and the majority of the aftermath that caused problems for the human population surrounding the mountain was the cloud of ash. The rubble from the mountain was limited to the area nearby and did not destroy any of the cities in the area. Additionally, the area is not as populated. The two images below show the major cities and it is clear that Mount St. Helens does have a reasonable distance between the densely populated metropolitan areas.
5. Utah does have the potential for multiple natural disasters, including wildfires, earthquakes, and floods. However the largest natural disaster that would impact the Utah area would be the eruption of the Yellowstone Volcano. Although the volcano is not located within the near vicinity, the massive eruption, devastating earthquakes, and ash clouds could greatly impact the state of Utah. In the last eruption, feet of ash were found in neighboring states such as Nebraska, Idaho, and Montana. In the event, there was an eruption, the entire northwest would be effected.
6. There are multiple factors that contribute to the future potential eruption of the Yellowstone Volcano. The volcano is still active, and unfortunately it is difficult to predict when in the future it will erupt. There are early warning signs that can help as indicators of such an event, however they are not able to provide information decades in advance. Earthquakes in the area could provoke the eruption. During the year, the Yellowstone area experiences 1000-2000 minor earthquakes a year, all with a magnitude of 3.0 or less. However, a significant earthquake of a higher magnitude of 6.0 could cause devastating effects. Additionally, the magma chamber pressure fluctuates, which if the increase or decrease is significant, it could be an indication of increase pressure build up within the volcano.
7. People in the Northwest Region should be prepared for an eruption, and in order to limit their vulnerability during the time of natural disaster, people should prepare an effective disaster relief and emergency action plan. In the event of an eruption, there may be limited time to prepare people for evacuation. In the event of emergency evacuation, people who have a plan set up will be more equipped at dealing with the stress of the situation. An emergency travel kit, supplies, and plan of action should be prearranged. The plan should include where to evacuation to in the time of crisis. It would be helpful to locate multiple destination possibilities, with taking into account, other areas that may be evacuated too. Volcanoes and earthquakes are more difficult to prepare for, making it difficult to fully reduce the vulnerability of being effected by the natural disaster.
Reflection:
For this assignment it was interesting to learn about the Mount St. Helens eruption in 1980 and the Loma Prieta Earthquake. Prior to this assignment I was not aware that there was such a large earthquake in 1989. I was also not aware that there were many larger earthquakes in the California area over the past two decades. The San Andreas fault does appear to be a key contributor to those earthquakes as well.
In regards to any misconceptions that I may have had prior to the assignment was for both the California area, and how Loma Prieta is located so close to multiple cities, including San Jose and San Francisco, and that Mount St. Helens is not that far from Portland, OR. When using Google Earth as an aid to completing these projects, it helps to get a better idea of the distance between areas, and the a better understanding of the general surrounding area.
7. People in the Northwest Region should be prepared for an eruption, and in order to limit their vulnerability during the time of natural disaster, people should prepare an effective disaster relief and emergency action plan. In the event of an eruption, there may be limited time to prepare people for evacuation. In the event of emergency evacuation, people who have a plan set up will be more equipped at dealing with the stress of the situation. An emergency travel kit, supplies, and plan of action should be prearranged. The plan should include where to evacuation to in the time of crisis. It would be helpful to locate multiple destination possibilities, with taking into account, other areas that may be evacuated too. Volcanoes and earthquakes are more difficult to prepare for, making it difficult to fully reduce the vulnerability of being effected by the natural disaster.
Reflection:
For this assignment it was interesting to learn about the Mount St. Helens eruption in 1980 and the Loma Prieta Earthquake. Prior to this assignment I was not aware that there was such a large earthquake in 1989. I was also not aware that there were many larger earthquakes in the California area over the past two decades. The San Andreas fault does appear to be a key contributor to those earthquakes as well.
In regards to any misconceptions that I may have had prior to the assignment was for both the California area, and how Loma Prieta is located so close to multiple cities, including San Jose and San Francisco, and that Mount St. Helens is not that far from Portland, OR. When using Google Earth as an aid to completing these projects, it helps to get a better idea of the distance between areas, and the a better understanding of the general surrounding area.