Geohazard Flashcards
A weak to violent shaking of the ground produced by the sudden movement of rock materials below the earth’s surface
Earthquake
Movement caused by forces deep within the earth’s interior
Earthquake
Origin of earthquake
- Volcanic Activity
- Tectonic Activity
The origin of an earthquake occurs at depths between ____ and ________ km at the focus
5 and 700 km
A number that characterizes the relative size of an earthquake
Magnitude
The reading or graph produced to read the magnitude
Seismogram
The machine that records the magnitude
Seismograph
Scales used in measuring magnitude
- Richter Magnitude/ local magnitude (ML)
- Surface-wave magnitude (Ms)
- Body-wave magnitude (Mb)
- Moment of magnitude (Mw)
A quantitative measurement that relies on data gleaned from seismic records to estimate the amount of energy released at an earthquake source
Magnitude
Describing the severity of an earthquake in terms of its effects on the earth’s surface and on humans and their structures
Intensity
Used to measure the earthquake’s intensity
Modified Mercalli Scale
The point on the earth’s surface vertically above the focus of an earthquake
Epicenter
The location where the earthquake begins
Focus / Hypocenter
It is released during an earthquake
Seismic Waves
Small Tremors that follows strong earthquakes, sometime they are stronger than the actual quake
Aftershock
Gradually diminish in frequency and intensity over a period of several months
Aftershock
Small earthquake that precede a major earthquake by days or in some cases year
Foreshock
Magnitude of 1986 Casiguran Earthquake
Ms 7.3
Magnitude of 1973 Ragay Gulf Earthquake
Ms. 7.0
Magnitude of 1976 Moro Gulf Earthquake
Ms. 7.9
Magnitude of 1983 Laoag Earthquake
Ms 6.5
Magnitude of 1990 Luzon Earthquake
Ms 7.8
Magnitude of 1990 Bohol Earthquake
Ms 6.8
Magnitude of 1990 Panay Earthquake
Ms 7.1
Magnitude of 2002 Sultan Kudarar Earthquake
Ms 6.8
Magnitude of 2003 Masbate Earthquake
Ms 6.2
Magnitude of 2012 Negros Earthquake
Ms 6.9
Magnitude of 2012 Guiuan, Eastern Samar Earthquake
Ms 7.6
Magnitude of 2013 Bohol Earthquake
Ms. 7.2
Magnitude of 2017 Batangas Earthquake
Ms 5.5 Earthquake Swarm
Magnitude of 2017 Jaro, Leyte Earthquake
Ms 6.5
Magnitude of 2017 Nasugbu, Batangas Earthquake
Ms 6.2
Year of the Ms. 7.3 Casiguran Earthquake
1968
Year of the Ms. 7.0 Ragay Gulf Earthquake
1973
Year of the Ms. 7.9 Moro Gulf Earthquake
1976
Year of the Ms. 6.5 Laoag Earthquake
1983
Year of the Ms. 7.8 Luzon Earthquake
1990
Year of the Ms. 6.8 Bohol Earthquake
1990
Year of the Ms. 7.1 Panay Earthquake
1990
Year of the Ms. 6.8 Sultan Kudarar Earthquake
2002
Year of the Ms. 6.2 Masbate Earthquake
2003
Year of the Ms. 6.9 Negros Earthquake
February 2012
Year of the Ms. 7.6 Guiuan, Eastern Samar Earthquake
August 2012
Year of the Ms. 7.2 Bohol Earthquake
October 2013
Year of the Ms. 5.5 Batangas Earthquake
April 2017
Year of the Ms. 6.5 Jaro, Leyte Earthquake
July 2017
Year of the Ms. 6.2 Nasugbu, Batangas Earthquake
August 2017
Earthquake Preventive Measures
- Seek Shelter under stable table or under door frames
- If outside, stay away from buildings, bridges and electricity pylons and move to open areas
- Avoid areas at risk from secondary processes, such as landslides, rockfall and soil liquefaction
- After an earthquake, check gas, water and electricity pipes and lines for damage
- Listen to the radio and follow the instructions issued by the authorities
A process by which water-saturated sediment temporarily loses strength and acts as a fluid when you wiggle your toes in the wet sand near the water at the beach
Liquefaction
Ensure that the structure has ductility, the ability to accommodate large deformations and adjustable supports to correct against differential settlements of the soil
Building Liquefaction Resistant Structures
Increasing the density and/or improving the drainage characteristics of liquefiable soil reduce liquefaction hazards by limiting increases in water pressure within the soil during and earthquake
Soil Improvement Techniques
A technique in which a vibrating prove is used to penetrate the soil up to a depth of 100 feet and the vibration of the probe caused the grain structure surrounding probe to collapse and consequently increase in density. The soil is then probe in a grid like pattern to achieve densification of the soil in a given area
Vibroflotation