Portfolio Summary

Maximum California Earthquake Portfolio

Total Insured Value

$4.61B

Properties

1,232

California Counties

Largest Single Risk

$272M

01 — Geographic Distribution

Geographic distribution

Top five counties account for 93% of TIV; Los Angeles and Monterey together account for 82%. Monterey holds the largest property count (mid-market wood-frame residential); Los Angeles holds the largest TIV.

TIV Share by County

County	Properties	Total TIV	% of TIV
Los Angeles	140	$2.25B	48.8%
Monterey	977	$1.55B	33.6%
San Francisco	5	$232.9M	5.0%
Santa Barbara	15	$173.2M	3.8%
Santa Cruz	12	$85.0M	1.8%
All Other (25)	83	$311.6M	6.8%

02 — Composition

TIV distribution and construction

56.6% of properties carry TIV under $1M; 1.4% of properties account for 22% of TIV. Wood frame is the dominant construction type at 88% of count.

TIV Distribution by Band

< $1M

$1M - $5M

$5M - $10M

$10M - $25M

$25M - $50M

$50M+

Construction Type

Wood frame

Tilt-up

Steel

Concrete

03 — Vintage

Vintage distribution

Year built relative to California seismic-code milestones. From the 1,143-property sub-sample with year-built data (87% LightBox coverage). Median year built: 1966.

Properties by Construction Era (n=968)

Era	Properties	% of Subset	Code Era
Pre-1933	81	8.4%	Pre-Long Beach quake
1933 - 1971	436	45.0%	Pre-Sylmar
1971 - 1994	293	30.3%	Pre-Northridge
1994 - 2008	97	10.0%	Post-Northridge
2008+	61	6.3%	Modern IBC

04 — Building Geometry

Building footprint and orientation

Per-property building geometry derived from satellite footprint extraction. Long-axis azimuth, axes, area, and height are reported on a 1,296-property sub-sample (98%) with successful footprint extraction.

Median Aspect Ratio

1.42

long ÷ short

Median Footprint

249 m²

Median Height

5.1 m

Median Azimuth

89°

long axis

Building Height (n=920)

< 4m (≈1 story)

164 · 17.8%

4-7m (≈2 story)

612 · 66.5%

7-12m (≈3 story)

129 · 14.0%

12-30m

14 · 1.5%

30m+ (high-rise)

1 · 0.1%

Aspect Ratio (long ÷ short, n=999)

Square 1.0-1.25

337 · 33.7%

Compact 1.25-1.5

217 · 21.7%

Moderate 1.5-2

261 · 26.1%

Elongated 2-3

147 · 14.7%

Highly elongated 3+

37 · 3.7%

Footprint Area (n=999)

< 100 m²

56 · 5.6%

100-200 m²

275 · 27.5%

200-300 m²

275 · 27.5%

300-500 m²

192 · 19.2%

500-1,000 m²

133 · 13.3%

1,000+ m²

68 · 6.8%

Distribution shows a mild bias toward east-west and ESE-WNW alignment, consistent with the LA / Monterey street-grid mix. Orientation can affect torsional response under non-axial ground motion.

05 — Retrofit

Seismic retrofit status

50 confirmed retrofits to date. Additional properties are being validated as we integrate a newly discovered datasource.

Status

Status	Count	TIV
Seismically retrofitted	50 (4.1%)	$498M
Not retrofitted or unconfirmed	1,182 (95.9%)	$4.11B

Retrofit Rate by Fault Distance

Distance	Retrofit Rate
< 1 km	4.0%
1 - 5 km	3.0%
5 - 10 km	10.2%
10 - 25 km	2.7%
> 25 km	0.0%

06 — Fault Proximity

Distance to nearest mapped fault

Computed against California Geological Survey fault traces for the 1,320-property enriched set. Median distance: 1.16 km; mean: 2.53 km. The bearing distribution reflects the strike of the San Andreas system.

Properties by Fault Distance (n=1,320)

< 1 km

624 · 47.3%

1 - 5 km

538 · 40.8%

5 - 10 km

112 · 8.5%

10 - 25 km

36 · 2.7%

> 25 km

10 · 0.8%

Distance to Nearest Fault	Properties	% of Subset
< 1 km	624	47.3%
1 - 5 km	538	40.8%
5 - 10 km	112	8.5%
10 - 25 km	36	2.7%
> 25 km	10	0.8%

Top Fault Exposures by TIV

07 — Fault Age

Fault age — CGS classification of the nearest fault

CGS classifies faults by most-recent rupture age. The age of the nearest fault is one input to seismic hazard. Two-thirds of the enriched set sits closest to a Quaternary fault; about one-third is closest to a Late Quaternary fault.

Distribution by Age Class (n=1,320)

Holocene/Historical

10 · 0.8%

Late Quaternary

415 · 31.4%

Quaternary

895 · 67.8%

Age Class of Nearest Fault	Properties	%	Hazard Tier
Holocene / Historical (< 11,700 yr)	10	0.8%	Highest
Late Quaternary (< 130,000 yr)	415	31.4%	Moderate
Quaternary (< 1.6 M yr)	895	67.8%	Background

08 — Composite Score

Majelyn Earthquake Risk Score (MERS)

A proprietary 0-100 risk score grounded in peer-reviewed research and industry-accepted weighting factors. MERS combines ground motion intensity (USGS NSHM 2023), fault proximity, site conditions (ASCE 7-22 Vs30 / NEHRP), CGS geologic hazard zones, and structure vulnerability. Higher scores indicate higher modeled seismic risk.

v0.1 · Beta

Median MERS

of 100

Mean MERS

50.5

σ = 5.9

Q1 - Q3

47 - 53

interquartile range

Min / Max

22 / 80

portfolio range

Score Legend & Portfolio Distribution (n=1,320)

0-20

Low

3 (0.3%)

21-40

Moderate

202 (20.1%)

41-60

Elevated

793 (78.9%)

61-80

High

7 (0.7%)

81-100

Very High

0 props

Score Distribution (10-point bins)

Sub-Score Composition (Mean, 0-100, n=1,320)

Sub-Score Breakdown

Ground Motion

90.4

Site Conditions

50.1

Fault Proximity

47.1

Structure Vuln.

33.8

Geologic Hazards

2.6

Ground Motion saturates near the cap (California baseline seismicity). Geologic Hazards mean is lifted by the 70 properties (5.3%) inside a CGS overlay zone; the median is 0 because the rest sit outside.

09 — Per-Site Vs30 / NEHRP

Site class — per-site Vs30 and NEHRP classification

Per-site Vs30 derived from CGS MS-48 (Wills 2015 / Thompson 2022 30m raster). NEHRP class assigned per ASCE 7-22. Reported on the full 1,320-property enriched set. Median Vs30 is 447 m/s; range 226 - 935 m/s.

Median Vs30

447 m/s

Mean Vs30

429 m/s

Vs30 Range

226 - 935

Site-Specific Required

0 of 1,320

NEHRP Class Distribution

NEHRP Class	Vs30 Range (m/s)	Properties	% of Subset
BC	540 - 760	3	0.2%
C	366 - 540	150	11.4%
CD	263 - 366	642	48.6%
D	213 - 263	442	33.5%
DE	152 - 213	83	6.3%

Eighty-three properties (6.3%) classify as DE — soft soil. None classify as E, and none triggered the ASCE 7-22 site-specific analysis threshold (E with reference PGA ≥ 0.4 g).

10 — Design Ground Motion · USGS NSHM

Design ground motion — USGS NSHM

USGS National Seismic Hazard Model — 2% probability of exceedance in 50 years, at NSHM reference site class BC. Reported on the 1,320-property enriched set.

Median PGA

0.709 g

Mean PGA

0.733 g

Range

0.19 - 1.42 g

≥ 0.6 g (Very High+)

93.1%

PGA Band Distribution (n=1,320)

Moderate (< 0.4g)

15 · 1.1%

High (0.4-0.6g)

76 · 5.8%

Very High (0.6-0.8g)

1,041 · 78.9%

Severe (≥0.8g)

188 · 14.2%

Note on Fpga:Above ~0.4 g reference PGA, ASCE 7-22 caps the Fpga site-amplification factor at 1.0 for all site classes (nonlinear soil response). Site-adjusted PGA tracks reference PGA in this portfolio's range.

11 — State Hazard Zones · CGS

State seismic hazard zone overlays

California Geological Survey Seismic Hazard Zones — Alquist-Priolo (active fault), liquefaction, and earthquake-induced landslide. Computed for the 1,320-property enriched set.

Properties in CGS Zones (n=1,320)

Liquefaction

45 · 3.4%

Landslide

18 · 1.4%

Alquist-Priolo

8 · 0.6%

In any CGS zone

70 · 5.3%

Zone	In Zone	% of Subset
Liquefaction	45	3.4%
Alquist-Priolo (active fault)	8	0.6%
Earthquake-induced landslide	18	1.4%
In any CGS zone	70	5.3%

12 — Wildfire Exposure

Wildfire exposure — NIFC perimeters and USFS WHP

Two signals are reported. The first is point-in-polygon intersection with NIFC historical fire perimeters. The second is USFS Wildfire Hazard Potential at the county level.

NIFC Historical Fire Perimeter (n=1,320)

Signal	Properties	% of Subset
Inside historical fire perimeter	4	0.3%
Within 1 km of any perimeter	55	4.2%

Inside-perimeter intersections fall in the 2025 Palisades Fire footprint (Pacific Palisades / Malibu). Within-1km matches are predominantly Palisades-adjacent.

USFS Wildfire Hazard Potential by County (n=1,320)

County	Props	Direct	Indirect
San Luis Obispo	8	41.3%	46.6%
Santa Cruz County	16	36.7%	33.3%
Monterey County	1,048	29.5%	23.5%
Santa Barbara	15	25.5%	40.9%
Riverside County	4	17.2%	42.9%
Los Angeles	136	5.0%	14.6%
San Francisco	7	0.4%	3.0%

Coverage Notes

What's in the numbers

Headline portfolio totals (TIV, county, TIV distribution, construction) are computed on the 1,232 source SOV line items from the original portfolio file.
Fault proximity, fault age, NSHM ground motion, CGS overlays, building geometry, per-site Vs30 / NEHRP, and MERS (composite, sub-scores, flags) are computed on the 1,320-property enriched set. The enriched count exceeds the SOV count because Mapbox occasionally resolved one source row to multiple distinct buildings (correctly).
Vs30 source: CGS MS-48 (Wills 2015 / Thompson 2022 30m raster).
Fault traces: California Geological Survey.
Wildfire signals: NIFC point-in-polygon plus a 1 km buffer; USFS WHP at the county level.
Building geometry: derived from satellite footprint extraction (azimuth, axes, area, height).