Geology and Earthquakes

Importance of Midterms
- Midterms account for 40% of the overall grade in the course.
- Example calculation of grades:
- If a student has a 100% in assignments and scores 60% on the midterm:
  - Calculation:
    $ext{Overall Grade} = rac{(100 + 60)}{2} = 80$
- Emphasis on completing assignments diligently since they significantly impact final grades.
Midterms Content
- Topics covered in the second midterm include:
- Earthquakes
- Volcanoes
- Minerals
- The second midterm is scheduled for the last class before break.

1952 Earthquakes
- Two significant earthquakes occurred near Tehachapi and Arvin, California, in August and September 1952.
- Damage details:
  - Major destruction resulted in downtown buildings collapsing.
  - The Kern County Museum clock tower, historically located at the intersection of Truxton and Chester, was renovated and relocated due to damage.
Earthquake Impact on Bakersfield
- While past earthquakes did not occur in Bakersfield specifically, the affects extended into the city.
- Historical context of downtown architecture changes after severe earthquakes, resulting in the replacement of older brick buildings with newer constructions.

Understanding Local Risks
- Bakersfield's geographic proximity to the San Andreas Fault necessitates awareness of potential seismic activities.
- The importance of awareness and preparation for earthquakes, including personal anecdotes of earthquake experiences.

Tsunamis
- Describes the hazard posed by underwater earthquakes causing massive waves.
- Reference to the 2004 Indian Ocean tsunami:
- Death toll: 230,000 people killed.
Ghost Forests
- Ghost forests consist of dead trees preserved in coastal areas as evidence of past tsunamis.
- Example of radiocarbon dating:
- Trees dated from 1680 to 1720 indicate past seismic activity.

Fault Types
- A fault is defined as a fracture or break in the Earth's crust where movement occurs.
- Major vocabulary:
  - Fault: Break or fracture in the Earth's crust with displacement.
  - Focus: The point where the earthquake originates beneath the surface.
  - Epicenter: The point on the Earth's surface directly above the focus.
  - Fault Scarp: A visible scar on the Earth's surface caused by fault movement.
Types of Faults
- Normal Fault: Occurs when the crust is being pulled apart, causing the rock above the fault to slide down.
- Reverse Fault: Characterized by compression where the crust pushes upwards, causing the top side of the fault to rise.
- Strike Slip Fault: Lateral movement where two blocks of crust slide past one another without vertical displacement.

San Andreas Fault Overview
- The San Andreas Fault is a transform boundary between the Pacific Plate and the North American Plate.
- Notable for having numerous minor fault segments that may activate independently within operational timelines.
- Calculation of recurrence intervals:
- Average recurrence interval for significant earthquakes at specific segments, such as down at Fraser Park, estimated to be approximately 250 years.
- Historical context of last significant earthquake: occurred in 1857.

Seismic Gap Analysis
- Seismic gaps are regions along fault lines that have not experienced an earthquake in a significant period.
- Tools for measurement include satellite-based technology to track minute movements in geological formations.

Personal Anecdote
- Shared experiences of earthquake preparedness in daily life.
- Mention of historical earthquakes in localized areas and their impacts on both natural and human-made structures.
- Concluding thoughts on the psychological effects of anticipated seismic activity, readiness to survive natural disasters, and community awareness.