Term
| what is the pattern of the ratio of smaller faults to larger faults? |
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Definition
| the pattern of the ratio of smaller faults to bigger faults is consistent. This means that if there are 10 faults of magntiude 6 and 1 fault of magntiude 7, there will be 100 faults of magntiude 6 |
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Term
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Definition
| risk = probability * consequence |
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Term
| what is the difference between the probability of an event and the existing risk of an event |
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Definition
| the probability of an event is just the liklihood that it occurs. Risk takes into account the consequences of it occuring |
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Term
the estimation of rockfall risk he gave us is
Risklol = PH * PS:H * PT:S * VD:T
what is PH? |
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Definition
in the equation
Risklol = PH * PS:H * PT:S * VD:T
PH is the annual probability of of rockfall-iniating event i.e. earthquake |
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Term
Risklol = PH * PS:H * PT:S * VD:T
what is PS:H |
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Definition
Risklol = PH * PS:H * PT:S * VD:T
PS:H is the probability that a person, if present, is in the path of the boulder. This is asking: how many homes will get hit by boulders? |
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Term
Risklol = PH * PS:H * PT:S * VD:T
what is PT:S |
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Definition
Risklol = PH * PS:H * PT:S * VD:T
PT:S is the probability that a person is present when the event occurs. This changes if it's day and people are at work away from thier homes, or if it's night and everyone is asleep in thier homes |
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Term
Risklol = PH * PS:H * PT:S * VD:T
what is VD:T |
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Definition
Risklol = PH * PS:H * PT:S * VD:T
VD:T is the probability of a person who in the path of the boulder being killed. it's a "V" because that's a question of vulnerability, not probability. |
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Term
| 2 ways risks are reduced: what does Mark think of each? |
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Definition
2 ways to reduce risk from geohazards:
1. traditional hard engineering, trying to change the land to fit our interests. expensive, difficult, futile, and dangerous
2. changing our vulnerability to the existing threat. land use planning, better structures, better evacuation plans, avoiding dangerous areas |
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Term
| faults are like fractals. what implication does this have for predicting seismic hazard? |
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Definition
| because the ratio of smaller to larger faults is constant, we can look at the history earthquakes caused by small fualts, and predict where large faults will be. |
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Term
| predicting geohazards comes relies on measuring statistics of past events, and then using them as probablities of future events. what are three problems with this method? |
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Definition
the method of looking at the history of geohazard events and using that to predict the future has three problems:
1. the past isn't perfectly indicative of the future. changes over long time scales, like climate change need to be considered
2. catastrophic events may have return time that are longer than the history we can confidently analyze
3. the third problem isn't a scientific one, but a human one. We are often incentivized to plan for shorter time scales than we have data for. even if we know a hazard is coming in 200 years, we may only care about the next election cycle, or a couple generations |
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Term
| what law says occurance interval is 1/10 for earthquakes as you go up an order of magnitude? i.e. there are 1/10th as many magnitude 8's as magntiude 7's |
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Definition
| the G-R law says that earthquakes are 1/10th as likely as earthquakes one unit of magnitude lower |
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Term
| difference between hypocenter and epicenter? |
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Definition
| the hypocenter is the source of the earthquake in three dimensions. the epicenter is a pair of coordinates above the hypocenter |
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Term
| there was always a fault underchristchurch, but we didn't see much activity 2000-2010. Then we started to see a ton 2010-13. beyond the fact that large earthquakes spawn aftershocks, what is happening? |
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Definition
| the reason seismic activity jumped up so high in christchurch is a story of stress redistribution. also, earthquakes tend to cluster over time |
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Term
| is rupture velocity magnitude dependant? |
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Definition
| rupture velocity isn't magnitude dependant |
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Term
| if you are closer to the epicenter of an earthquake, how does this affect duration of shaking? |
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Definition
| if you are closer to the epicenter of an earthquake, the duration of shaking is generally longer |
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Term
| where is the most extreme shaking from a fault rupture |
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Definition
| although shaking last longer near the epicenter, shaking is most extreme at the ends of a rupture |
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Term
| why is it irresponsible to build a suburb in the area bexley is? |
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Definition
| the ground bexley was built on liquifies every 75-100 years |
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Term
| 4 imporant question to answer about fault rupture damage to forecast earthquake hazards, design sufficiently resilient structures, land-use reccomendations, and interpreting paleo-earthquakes in the record |
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Definition
4 important questions to answer about fault rupture damage
1. relationship between earthquake magnitude and surface displacement
2. thresholds between surface cracking and folding
3. width of deformation zone
4. return times of earthquakes |
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Term
if we can understand the relationship between fault rupture damage and earthquakes, what does this help us do? 4 things
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Definition
understanding the relationship between earthquakes and fault ruptures allows us to:
1. forecast earthquake hazards
2. make informed reccomendations for land use planning
3. design resilient structures
4. understand what rupture signals in the geologic record are telling us about earthquakes |
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Term
| is surface rupture length the same as fault length? |
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Definition
| surface rupture length may not be indicitive of fault length, which is the length of the whole fault |
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Term
| Mark's team measured surface slip from the darfield earthquake. what did they find? |
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Definition
| when Mark's people looked at surface slip from the darfield earthquake, they found there was large wavelength folding as well as discrete, more noticeable fracturing. if you just look at the more obvious fracturing signal, you miss the larger displacements and will underestimate displacement |
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Term
| how does the nature of surface ruptures make it easy to underestimate the displacement from an earthquake? |
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Definition
| the reason it is easy to underestimate displacement from an earthquake by looking at surface ruptures is that surface ruptures cause the classic fractured ground signal as well as more subtle, large scale bending. it's easy to come across the fracturing and measure it and think you are done, and miss some of the signal |
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Term
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Definition
| SRL is surface rupture length |
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Term
| why was the most damage caused by the second strongest quake in the canterbury earthquake sequence? |
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Definition
| the reason the second strongest quake in the canterbury earthquake sequence caused the most damage is becuse it was closer to CBD |
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