Submarine slope failures associated — 1964 M9.2 Great Alaska Quake in fjords of southcentral Alaska

Introduction

This tutorial explores the submarine slope failures associated with the 1964 Mw 9.2 Great Alaska Earthquake, focusing on the geological impacts observed in the fjords of southcentral Alaska. Understanding these events is crucial for assessing the risks of similar occurrences and their potential to generate tsunamis. Utilizing high-resolution data, this guide will outline the factors influencing sediment stability and slope failure in underwater environments.

Step 1: Understand the Context of the 1964 Earthquake

• Familiarize yourself with the basics of the 1964 Great Alaska Earthquake, which was one of the most powerful earthquakes recorded.
• Recognize the affected area, particularly Prince William Sound, which is directly over the epicenter.
• Understand that the earthquake produced significant ground shaking that led to widespread sediment destabilization in submerged fjords.

Step 2: Examine the Physical Characteristics of Fjords

• Study the unique physiography of fjords, including their depth, shape, and sediment composition.
• Analyze how these features influence sediment accumulation and stability.
• Consider the role of shaking intensity in determining how each fjord reacts to seismic activity.

Step 3: Investigate Sediment Response to Seismic Activity

• Utilize high-resolution Chirp sub-bottom profiles and shallow gravity cores to collect data on sediment layers.
• Focus on the following parameters:
  • Total volume of sediment remobilized during the earthquake.
  • Thickness of deposits left behind after failure.
• Compare fjords that experienced slope failures with those that remained stable to identify key differences.

Step 4: Assess the Potential for Tsunami Generation

• Understand the connection between submarine slope failures and tsunami generation.
• Evaluate how the characteristics of sediment deposits can influence tsunami size and impact.
• Analyze historical data from the 1964 event to quantify the relationship between sediment failure and tsunami generation.

Step 5: Apply Findings to Future Risk Assessment

• Use the insights gained from the 1964 earthquake to inform current geological assessments.
• Consider how similar seismic events could affect other coastal regions, particularly those with similar fjord characteristics.
• Advocate for monitoring and research in vulnerable areas to enhance tsunami preparedness.

Conclusion

In summary, the 1964 Great Alaska Earthquake serves as a vital case study for understanding submarine slope failures and their consequences. By investigating the interplay between sediment characteristics, shaking intensity, and tsunami potential, we can better prepare for future seismic events. Continued research and monitoring are essential to mitigate risks in affected coastal communities.