{"id":2583,"date":"2023-12-12T10:42:03","date_gmt":"2023-12-12T03:42:03","guid":{"rendered":"https:\/\/qyudos.co.id\/survey-hidrografi\/?p=2583"},"modified":"2023-12-12T11:14:49","modified_gmt":"2023-12-12T04:14:49","slug":"marine-geohazard-identification-part-i","status":"publish","type":"post","link":"https:\/\/qyudos.co.id\/survey-hidrografi\/marine-geohazard-identification-part-i\/","title":{"rendered":"Marine Geohazard Identification (part-I)"},"content":{"rendered":"\n

Submarine Landslide<\/strong><\/h3>\n\n\n\n

Hazard and Risk<\/strong><\/h4>\n\n\n\n

Hazard (Potential Hazard) is the intrinsic properties of a substance, equipment or work process that can cause damage or harm to the surrounding.  The potential hazard will remain a hazard without causing an impact or developing into an accident if there is contact (exposure) with humans.<\/p>\n\n\n\n

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Figure 1. Hazard, Exposure, and Risk.<\/figcaption><\/figure><\/div>\n\n\n\n

DIS\/ISO 45001 defines hazards as “sources or situations that have the potential to cause injury and illness” (clause 3.19).<\/p>\n\n\n\n

In the context of marine hazards based on causal factors, hazards can be divided into 2 types, namely:<\/p>\n\n\n\n

  1. Natural is a potential hazard caused by nature. The causes included in this natural factor are tectonics, gravity (slope), ocean dynamics, and erosion and accumulation.<\/li>
  2. Man-made are potential hazards caused by human activities.<\/li><\/ol>\n\n\n\n

    Hazards related to geological conditions are known as geological hazards or geohazards. One example of a geohazard is a submarine landslide.<\/p>\n\n\n\n

    <\/div>\n\n\n\n

    Submarine Landslide<\/strong><\/h4>\n\n\n\n
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    Figure 2. Schematic representation of submarine landslide evolution (Bryn et al., 2005).<\/figcaption><\/figure><\/div>\n\n\n\n

    Submarine landslides can be defined as any material movement that makes up the slope, downward toward the continental shelf. James Jonathan Hance, B.S. (2003) analyzed 534 submarine landslide events and concluded that there were 14 triggering mechanisms. In the database, 366 events had reported triggers and the rest (168 events) were unknown. The distribution of events is shown in the following graph.<\/p>\n\n\n\n

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    Figure 3. Trigger distribution of submarine landslide events (Hance, 2003).<\/figcaption><\/figure><\/div>\n\n\n\n

    225 landslides (40%) were triggered by earthquake and fault activity, 25% by rapid sediment accumulation, 11% by gas and gas hydrate dissociation, 9% by erosion, and the rest by other triggers.<\/p>\n\n\n\n

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    Figure 4. Slope angle distribution of submarine landslides (Hance, 2003).<\/figcaption><\/figure><\/div>\n\n\n\n

    Only 399 of the 534 events in the database have information on the slope angle, and the slope angle data is plotted in Figure 4. Figure 4 shows that the slope angle with the most events is between 3 – 4 degrees, which is a gentle slope.<\/p>\n\n\n\n

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    Figure 5. Cumulative frequency distribution of submarine landslide slope angles (Hance, 2003).<\/figcaption><\/figure><\/div>\n\n\n\n

    The cumulative frequency diagram shows that 80% of the 399 events had a slope angle of less than 10 degrees. Events occurring at gentle slope angles are not caused by gravity itself but by other mechanisms operating simultaneously. However, this does not eliminate the fact that submarine landslides can occur at gentle slope angles.<\/p>\n\n\n\n

    <\/div>\n\n\n\n

    Submarine Landslide Cases<\/strong><\/h4>\n\n\n\n

    In some cases, submarine landslides can cause other types of hazards and result in casualties. Here are some examples of the cases:<\/p>\n\n\n\n