Hazard DB schema

The hazard schema stores hazard scenario footprints and probabilistic hazard maps for multiple hazards. Hazards can be further defined into process types, each with a defined intensity unit as in cf_common.imt. For example, earthquake hazard may be represented as ground shaking, liquefaction or ground displacement.

The data structure contains entities nested as follows:

Event_set ( Event ( Footprint_set ( Footprint ( Footprint_data) ) ) )

The "Event set" stores one or more scenarios for a specific hazard. One "Event" represents one specific scenario (e.g. RP100, or one historical event). For each Event, one more "Footprint_set" can be available. This is a container for one or several "Footprints" where each is one possible realisation of an event. Uncertainty in the event characteristics and hazard footprint can be represented explicitly, through the inclusion of multiple events in an event set, and many footprints per event. Hazard footprints can be linked to another 'trigger event' footprint to represent cascading hazards. Hazard footprints can be assigned an occurrence frequency, and can represent a scenario footprint or return period hazard map. Inclusion of an event start and end time enables description of long-duration events.

ERD (hazard schema): hazard table contents (red) and links to common tables (yellow).

Table: hazard.event_set

The "event.set" entity contains information on a set of events for a given area, with event set duration, description, bibliography and defines the event set as probabilistic or deterministic.

Req	Field name	Type	Reference table	Description
*	id	INT		Unique number ID
*	hazard_type	VARCHAR	cf_common.hazard_type	Unique 2-char code
*	creation_date	date		The date of creation [ISO 8601 format]
	time_start	timestamp		The time at which the modelled scenario(s) starts [ISO 8601 format]
	time_end	timestamp		The time at which the modelled scenario(s) ends [ISO 8601 format]
	time_duration	interval		The extent of the time period covered by the events included in the current scenario hazard analysis [ISO 8601 format]
	description	TEXT		General information about this specific scenario hazard analysis
	bibliography	TEXT		Title and authors of studies containing relevant information
*	is_prob	BOOL		Wheter the event set represents a probabilistic (TRUE) or a deterministic (FALSE) analysis.
*	the_geom	GEOM		Associated geometry data (bounding box of data)

Table: hazard.event

The "Event" entity contains information about one specific scenario or hazard map included in an "Event Set". The information comprises event duration, occurrence probability or frequency, the hazard and process type, a link to a possible triggering event (for cascading events) and a text description for more context about magnitude, for example.

Req	Field name	Type	Reference table	Description
*	id	INT		Unique number ID
*	event_set_id	INT	hazard.event_set	Unique number ID of source exposure model
*	calculation_method	ENUM		The methodology used for the calculation of this event
	frequency	FLOAT		The frequency of occurrence of the present event (for the reference period see occurrence_time_span or occurrence_time_start and occurrence_time_end).
	occurrence_probability	FLOAT		The probability of occurrence in a given time interval defined either through the occurrence_time_start and occurrence_time_end or through the occurrence_time_span parameter. [float, adimensional]]
	occurence_time_start	timestamp		The start date (and possibly time) of the time period used to specify either the frequency or the occurrence_probability [ISO 8601 format]
	occurence_time_end	timestamp		The end date (and possibly time) of the time period used to specify either the frequency or the occurrence_probability [ISO 8601 format]
	occurence_time_span	interval		The duration (years) of the period used to specify either the frequency or the occurrence_probability
	trigger_hazard_type	VARCHAR	cf_common.hazard_type	Hazard type that triggered the event
	trigger_process_type	VARCHAR	cf_common.process_type	Process type that triggered the event
	trigger_event_id	INT		The ID of a event which is trigger for the simulation of the corresponding footprints
	description	TEXT		Provides additional information about this specific event

Table: hazard.footprint_set

The "Footprint set" entity contains a sub-group of the "Footprints" computed for an "Event"; all the "Footprint" in a "Footprint Set" have the same unit of measure, represent the same process type and their uncertainty is described in a homogenous way. Every "Footprint Set" instance will have the following attributes.

Req	Field name	Type	Reference table	Description
*	id	INT		Unique number ID
*	event_id	INT	hazard.event	The event.id parameter to which this footprint is associated
*	process_type	VARCHAR	cf_common.process_type	The typology of hazard process
*	imt	VARCHAR		Intensity measure types
	data_uncertainty	VARCHAR		This attribute describes the typology of uncertainty

Table: hazard.footprint

The "Footprint" entity contains information on a specific realisation of an "Event". The uncertainty of a particular event is captured either by the construction of many footprints or by a single footprint which contains information about uncertainty.

Req	Field name	Type	Reference table	Description
*	id	INT		Unique number ID
*	footprint_set_id	INT	hazard.footprint_set	The footprint_set.id parameter to which this footprint is associated
	trigger_footprint	INT
	uncertainty_2nd_moment	FLOAT

Table: hazard.footprint_data

The "Footprint_data" entity contains the footprint data: the value of intensity according to the intensity measure (IMT) described in "Footprint set", and the point location of the intensity value.

Req	Field name	Type	Reference table	Description
*	id	INT		Unique number ID
*	footprint_id	INT	hazard.footprint	The footprint.id parameter to which this footprint data is associated
*	the_geom	GEOM		Associated geometry data (point location)
*	intensity	FLOAT		The hazad process intensity value in the IMT described in "Footprint set"

Types

ENUM name	Types	Description
calc_method_enum	Inferred Simulated Observed	Type of calculation method applied to produce hazard footprint.