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Geology LibreTexts

1: Introduction

Course Mechanics . . .
Syllabus, lecture topics, exam dates, and other information is on ***

What you can expect to learn in this course . . .
This class will focus on seven major Earth Hazards: earthquakes, volcanoes, fires, tsunami, landslides, floods, and hurricanes

Plate Tectonics: The driving engine
We’ll start with a global view, looking at plate tectonics and how it drives many natural disasters.

Earthquakes
Earthquakes can occur anywhere, but tend to occur more frequently along plate boundaries.
The class will be global in extent, but will use many examples of geologic hazards in California. We’ll talk about important earthquakes in California such as San Francisco 1906, Loma Prieta 1989, and Northridge 1994. We’ll take a tour along the San Andreas and discuss its effects on the seismicity of California from south to north. We’ll talk about important earthquakes around the world – why they happen where they do, important effects such as the 2011 Tōhoku earthquake and tsunami off the coast of Japan, the 2010 Haiti earthquake, and others, and about likely future events. We’ll talk about why it’s proven so difficult to predict earthquakes, about the concepts of hazard and risk, and about earthquake preparedness. We’ll even have an in-class earthquake drill!

Tsunami
Earthquakes, landslides, and volcanic eruptions can also generate tsunami.
- 2004 Indonesian earthquake and tsunami killed ~220,000 along the margins of the Indian Ocean
- 2011 earthquake in Japan generated a tsunami that killed more than 15,000 people, destroyed communities, and triggered a nuclear disaster.
- 1964 Alaska earthquake killed several people on the beach at Crescent City in northern Calif
- 1960 earthquake in Chile killed almost a hundred people in Hilo Hawaii

Volcanic Hazards
Tectonics also controls the distribution of volcanoes worldwide, but not all volcanoes are created equal, with some being much more hazardous than others. We’ll talk about the different types of eruptions and the hazards they represent, and take a tour of some historically important eruptions. We’ll talk about how volcanic eruptions can affect people and cultures far away from the volcano.

Landslides and mudflows
In contrast to volcano and earthquake hazards, landslide hazards and mudflows are typically local phenomena that require local research and mitigation. We’ll talk about the process of mass wasting and the events that trigger landslides.

Floods
Floods kill more people every year than any other geologic hazard. We’ll talk about how rivers behave when they are not flooding, and what happens when they flood. We’ll learn about the concept of the 100 year flood, and about significant floods around the world and here in California.

Fires
The confluence of drought, past forest management practices, and human development at the urban-forest interface has increased the risk of major wildfires in California. As of the start of the quarter, we are seeing the impact right now. We will learn about how fires behave and their impact on humans – and how policy decisions can affect the risk.

Hurricanes and Typhoons
Many parts of the world are vulnerable; population growth in coastal areas increases vulnerability. In the US, the Atlantic coast and Gulf of Mexico states are most vulnerable. Costs of hurricanes have increased, while the number of deaths have decreased.

Hurricanes and Typhoons
Many parts of the world are vulnerable; population growth in coastal areas increases vulnerability. In the US, the Atlantic coast and Gulf of Mexico states are most vulnerable. Costs of hurricanes have increased, while the number of deaths have decreased.

Summary:
Understanding combined scenarios can help societies and individuals plan and mitigate risk.
We’ll always return to the human element. We don’t just focus on the scientific reasons for disasters. Human decision-making, population density and socioeconomic status are all factors that can turn a geologic event into a natural disaster.
Throughout the course, we’ll touch upon how each of these geohazards affect people. You’ll learn about forecasting & preparedness and how you can protect yourself from personal danger caused by each of these hazards. You’ll gain a greater appreciation of the violence of these events and learn how to avoid them or live through them.

Some concepts will come up again and again:
Recurrence interval: The average time between past events.
Random events: Like a coin toss, these are independent of previous events.
Forecast: The future likelihood of a random event
Hazard: something that can cause harm (contrast with RISK)
Risk: the likelihood that a hazard will cause harm (contrast with HAZARD)

Summary
1. GEL 17 focuses earthquakes, tsunamis, volcanoes, fires landslides, floods, and hurricanes.
2. Plate tectonics drives of many of these hazards (earthquakes, tsunami, volcanoes, and landslides).
3. Natural hazards are common: they occur in many places and are occurring somewhere all the time.
4. Natural disasters are result of people living in places with natural hazards.
5. Understanding the origins of natural hazards helps us to mitigate their effects