Geologic

Process and
Hazards
Geologic processes
• are naturally occurring mechanism that happens on earth.
• It affects human life all the time but are not mostly noticeable if they don’t cause threat like loss
of life or property.
• Such life or property threatening processes are called natural disasters.
• Among these geological processes are,
❖Earthquakes
❖volcanic eruptions
❖Landslides
❖Tsunamis
❖Floods
❖Drought
❖Hurricanes
❖tornadoes etc.
❖All of these processes have existed throughout the history of the earth and they have become
hazardous because of their negatives effects on human.
Earthquake
• Earthquake is the sudden movement of the Earth’s
crust that results from the release of accumulated
strain from tectonic and volcanic activities. It is
usually classified according to its depth.
• Shallow earthquakes happen at depths less than 70
km.
• Intermediate earthquakes happen at depths of 70
to 300 km.
• Deep earthquakes take place at depths more than
300 km.
 Effects of Earthquake
• Ground shaking is the vibration of the
ground during an earthquake.
• Liquefaction refers to the phenomenon
where soil loses strength temporarily
and behaves as a liquid rather than
solid.
• Surface faulting is the tearing of the
ground surface caused by displacement
along faults during earthquakes.
• Fire is an indirect hazard of earthquakes.
When structures collapse, gas and
electrical lines are at risk of starting fires.
Volcanic Eruption
• Volcanic eruption is the discharge of materials and gas
from the interior of the volcano to the surface and to
the atmosphere.
Movements of Materials during Volcanic Eruption
• Pyroclastic flows are the rapid movement of masses of
hot and dry pyroclastic materials and gases along the
surface during an eruption.
• Lahar is a catastrophic mudflow on the slopes of
volcanoes.
Landslides or Mass
Wasting
• Landslides or mass wasting is the general term that
refers to the movement of Earth material down slopes.
• Mudflows are fast moving wet flows. It is synonymous
to lahars but the latter is composed of mixture of
water and volcanic materials.
• Earthflows forms on hillsides during heavy rains or
melting of snow.
• Rockfall is the movement of unconsolidated material
downslope caused by gravity.
Tsunamis
• Tsunamis are created by weather disturbances such as
an earthquake, landslide, volcanic eruption or meteorite.
Thus, creating series of enormous waves.
• Earthquake is the sudden movement of
Earth’s crust caused by movements along
faults.
• Volcanic eruptions may cause pyroclastic
flows and lahar and may release toxic gases.
• Landslides may be in the form of mudflow,
earthflow or rockfall. All can impose danger to
human lives and structures.
• Tsunamis are seismic sea waves that are
brought about by various natural phenomena
such as earthquakes and volcanic eruptions.
 Hazard Maps
• Hazard maps are simply maps that show areas that are
prone to particular hazards. These maps are developed
using advanced software and tons of data.
Government Involvement in Hazard Map Generation
• In the Philippines, agencies such as the following create
hazard maps to prevent damages in the event of
earthquakes, volcanic eruptions and landslide.
• Philippine Institute of Volcanology and Seismology (PHIVOLCS)
• Department of Science and Technology (DOST)
• Mines and Geosciences Bureau (MGB)
• National mapping and Resource Information Authority (NAMRIA).
 Parts of a Hazard Map
• Hazard maps contain elements that are vital to
information dissemination.
• The title of the map gives you the name of the area
mapped. This serves as the identification of the map.
• Legends and symbols in a hazard map includes routes
to evacuation centers, evaluation of disaster
possibility or frequency, warning and evacuation
system and disaster-related basic information.
• North arrow gives the user a sense of direction. This
can be used to properly navigate the map.
• Scale of the map is the ratio between the distance on
a map and on the ground.
Hazard Maps for Geologic
Hazards in the Philippines
• Earthquake Prone Areas Map
• The base map of the Philippines appear to have
colors ranging from white to orange to dark
orange. This color range corresponds to the
frequency of earthquakes that have taken place
in the area within a given time frame.
• The red circles represents the magnitude of the
earthquakes. Smaller circles suggest lower
magnitude values starting from magnitude 5.5.
 Tsunami Prone Areas Map
• Coasts that are delineated
suing sky blue color have high
potential to hazards.
• Coasts that are designated
with pink color suggest
potential tsunami generated
by local earthquakes.
• The coasts on the east of the
Philippine Archipelago is
characterized by yellow edges
which means that the areas
are at risk of locally and
foreign generated tsunamis.
Distribution of Volcanoes Map Areas Susceptible to Landslide Map
• Three differently colored triangles represent • Different shades of brown were used to denote
three types of volcanoes – active, potentially susceptibility levels. Areas in dark brown color are high
active and inactive. danger zones.
 Coping With Geological hazards
Coping with Earthquake
• The following activities are needed to do before, during and after an earthquake.
• Before: Keep a kit that contains flashlights and batteries, first-aid-kit, fire
extinguisher, ready-to-eat food, and water.
• During: Stay calm and do not panic. DROP-COVER-HOLD should be done if one is
indoor during the earthquake

• After: Aftershocks may happen after an earthquake, always listen and read news.
Coping with Volcanic Eruption
• The following activities are needed to do before, during and after an eruption.
• Before: Have an emergency supply kit containing food, water, batteries,
flashlights and first-aid kit.
• During: Evacuation orders are issued by authorities and these should be
followed. Use a dust mask to help in breathing.
• After: Listen to radio or news about updates on the disaster.
Coping with Landslides
• The following activities are needed to do before, during and after a landslide.
• Before: Get a ground assessment of the property. Protect the property by planting
trees and land cover.
• During: Stay alert and awake and listen for unusual sounds that may indicate
landslides.
• After: Stay away from affected areas. Listen to news about the disaster. Watch
for flooding that may occur after landslides and debris flow.
Coping with Tsunamis
• The following activities are needed to do before, during and after a landslide.
• Before: Create and practice an evacuation plan for your family. Familiarity may
save your life.
• During: Save yourself - not your possessions. If you are not injured and offer
help to your neighbors. Prioritize people who may require special assistance.
• After: Do not return home immediately. Make sure to wait for the advice of
authorized officials. It is possible that there are still incoming waves.
 Landslides

Landslides Caused by Natural Phenomena and Human Activities

• Human activities that trigger landslides are mainly associated with construction that cause
changes in slopes,changes in surface water and groundwater regimes, removal of
vegetation and mining activities.
• Changes in groundwater and surface water regimes may be brought in due to changes in irrigation. If
done improperly, this may lead to increase in erosion.
• Removal of soil cover may cause an increase in groundwater level resulting in landslides.
• Mining activities may weaken the ground and cause it to collapse.

Ways on how to Lessen the Probability of Landslides

• Design structures properly, construct them in the best possible location
• Plant more soil cover like trees to prevent increase in erosion.